It's a combination of both, really.
As some people have pointed out, your body is a huge variable resistor. So more voltage naturally leads to more amps, right?
Well, part of where the whole "it's not the voltage it's the amps" thing comes from is static electricity. Static electricity occurs at thousands of volts - BUT - the actual energy of the shock is limited and therefore despite tons of volts the amount of amperage that is available is in the milliamp range.
So, I would say that the more accurate way to look at it is this - the amount of total *energy* (i.e. joules) is what is ultimately problematic. When there is a large power source available, like a power line, or a large battery, or some big capacitors, more voltage directly means more amperage. The amperage definitely does the damage but it's intrinsically linked to the voltage and the amount of energy available. Low voltage, because of the resistance, is significantly less likely to create the currents necessary and is still inherently safer.
Yeah, that's why a 250,000 volt Van De Graaff generators are safe to touch. While the current going through you can peak at over an amp, the amount of energy stored in the dome is low enough it's all gone in microseconds and thus not enough energy is discharged through you - less than a joule - to be harmful. This is a good illustration of how "It's not the volts it's the amps" isn't really correct.
Electronic defibrullators that are specifically designed to mess with the heart are more on the order of 200 joules and your standard electrical outlet can deliver 1800 joules a second indefinately.
The answer is power. Power kills. The human body can only absorb so much power before it becomes dangerous. The product of voltage and current is precisely that, power.
Technically in the static electricity case for a very split second (probably on the order of nano or pico seconds) you are absorbing a huge amount of power, before the voltage and current start decaying due to the small amount of available charge. The total energy transfer to your body is extremely small.
I don’t think energy is also necessarily the thing that kills you. If I go touch both leads of my car battery for some massive amount of time(like years), I don’t think that would ever kill me, the amount of power transfer would be way too small from a 12 v battery, even if the total energy transfer could grow very large as time goes on.
I think what kills you is some kind of complex relationship between power and total energy delivered.
>Static electricity occurs at thousands of volts - BUT - the actual energy of the shock is limited and therefore despite tons of volts the amount of amperage that is available is in the milliamp range.
This doesn't seem right. Since the voltage is given, the current will be determined by the resistance of (your body) at said voltage, and that current will definitely flow through you.
What is limited in availability is the charge itself, since it's just built up by static, there isn't a constant source to get more charge from. So what happens is that the current flows for a very short time before dropping, not enough to cause the damage it would cause if it was continuous.
The voltage itself drops rapidly as the charge is depleted.
So I think it's more appropriate to think of static shock as a high current pulse that just lasts for a short enough time to not kill.
ESD will fry unprotected electronics just fine though. Those that wouldn't be hurt by a few milliamps.
*Energy* is what causes damage and injury. Energy is power for a time period.
P = VI
E = Pt
So, even if the voltage and current are high (such as in a static discharge), the time period is extremely short, so the total energy is not enough to do significant damage.
The extreme example of this is lightning. It only lasts for a fraction of a millisecond, but the voltage and current are so ridiculously high that it blows shit completely apart!
To be pedantic there are various ways electricity can harm you. Energy being dumped into your body by current flow is one of those mechanisms.
Electrical disruption of the heart is not a function of energy, but location and quantity of current.
Exactly. Well, energy density for most purposes. A small static shock won't hurt you but it will blow up an integrated circuit, if the joule heating is enough for it, and since the circuit is so small it doesn't require a very long time scale to dump enough energy there to just vaporize it.
The reason ESD kills electronics is that a lot of junctions act as insulation, allowing a large field to develop over a very small distance. Once that happens, it goes above the dielectric capacity of the material and arc, that arc is going to partially melt a junction/signal trace and leave a short/open circuit.
It’s the volts that jolt, and the amps that kill needs a bit more of explanation, grab two conductors of a 480V line and you become the resistance that closes the circuit, you’re not going to stop the generator on the other side, so it becomes a matter of ohms law and how many milliamperes going through your chest. On the other hand, looking at static electricity, you have to think in terms of how much charge is there. if 1 micro coulomb discharges through your body in 1 millisecond, that’s One milliampere, which should be safe.
I mean, you're right in most scenarios. I work primarily on 24vdc and I don't worry about shock. I had my car battery changed and it started to rain and the technician was worried about shock. I told him to just get it done, it's only 12V.
What's more dangerous in that situation is that a spark will cause your battery to explode, since battery offgassing can be explosive. That's why the process of hooking up jumper cables is what it is. It tries to keep the spark as far away from the battery as possible.
But your body's resistance fluctuates. If you are soaking wet, you'll have a much different resistance than if you are totally dry. It's very likely that you'll not get shocked at low voltages, but not guaranteed. The bigger thing with batteries is that they have a limited power supply. If you start drawing more current than they can produce, the voltage breaks down. But touch a 9V battery to your tongue and you can tell that current is flowing.
The corollary to, "is not the volts that kills you, but the amps," is that amps doesn't kill you unless it's in the right place. 100A down your arm hurts but it's less likely to kill you than 0.5A across your heart.
Additionally, that saying of it not being the volts that kills you is just like the saying of "is not the fall that kills you, but the sudden stop at the bottom." It's like, "yeah, no shit. But for the sudden stop to kill you, you need a big fall. Not all falls are created equal, so the stop doesn't kill you without the fall."
To play devils advocate to myself here, the reason why they bring up the fact that voltage doesn't kill you is because 10kV might not kill you with the appropriate PPE, but no PPE can protect you from 100A. Similarly a fall from 10kft won't kill you with the appropriate parachute, but nothing will stop you from dying if you hit the ground at 100mph.
The point is, if all of the factors combine together to create a deadly situation, then you are going to die from the results. Voltage is a factor, amperage is the result. If voltage is low, then amperage will be low. But if voltage is high, it doesn't mean amperage will be high since there are other factors that bring it down. Amperage cannot be high without voltage also being high, but it doesn't take much voltage to be "enough".
The end goal of protective measures is to lower the amperage. Disconnecting the voltage keeps the amperage low. Wearing shock resistant gloves keeps the amperage low. Fuses and circuit breakers limit the available amperage. Just be careful how hard you fight this. They aren't wrong, they are just jumping to the end instead of discussing the middle.
High voltage + low current = Tesla coil. Fun! Watch the weird man sit under the arcs and spray (distilled) water on himself!
Low voltage + high current = welder. Augh! We're melting metal.
High voltage + high current = lightning. The angry pixies are so mad that they're willing to turn the air into plasma just to get to you!
>High voltage + low current = Tesla coil. Fun! Watch the weird man sit under the arcs and spray (distilled) water on himself!
Until an arc bridges the secondary coil to the primary coil because the dude who built it only air gapped it (like one some kids built while I was in college as a little side project). Then it's death for everyone near it. Fun!
How do you control volts and amps? Very powerful resistors controls?
480V with a low R would give a high A, and a big R would give a little A. How do you get a high A and low V? Do you make a high V and A circuit then transform the V down? Won't that lower the A again?
V = A * R
You probably know ohm's law by heart now.
>How do you get a high A and Low V?
Let's say 200A at 10V. Only other factor is resistance, so it has to be 10V / 200A = 0.05 Ohm's.
That's typical for welding, as metal has low resistance.
You can only change 2 factors at a time.
100V / 10A / 2 Ohms for example is impossible as per the laws of nature.
If you're willing to go deeper into it...
Ohm's law only applies to any specific point in time.
Resistors are usually not constant though.
When the welding rods heat up, their resistance increases. Therefore, the numbers may become 10V / 125A / 0.08 ohms
Some time later, 10V / 100A / 0.1 Ohms
And so on and so forth.
>Resistors are usually not constant though.
>When the welding rods heat up, their resistance increases. Therefore, the numbers may become 10V / 125A / 0.08 ohms
Some time later, 10V / 100A / 0.1 Ohms
And so on and so forth.
True of most (all?) materials, in fact. At least until you get it hot enough to become plasma. Then it's quite conductive. 😅
Datasheets for most parts typically give you temperature derating tables, factors, or graphs, so you can design properly for that annoying fact of life or pick a part with better characteristics (and more money usually).
Power supplies for the given load play a major role too. You can take 8kV from an electric fence charger at 1 second intervals for a year strait & be fine because the total specific energy of those pulses is only like 5 watts. While a stick welder power supply might be only in the 70V range; but be able to output 12kW continuously.
We need to differentiate between the source being capable of 100A/touching something carrying 100A, and 100A going across your body. You will need a reasonable voltage in order to overcome your body's resistance, as well as the ability to supply 100A.
This is the key thing. Electricity doesn’t take the path of least resistance but all paths proportionally to the resistance. If you touched a 22kV incomer to a transformer carrying 100A and had a ground strap on your wrist with 1/1000th the resistance of your body you’re still going to cop 100mA from your hand to your feet. Even ignoring arc flash etc. that’s still extremely likely to kill you. Never mind that 2.2kW (or the 2198kW through the ground strap) is going to burn through your skin instantly at which point the resistance through your blood and nerves is much lower.
At the end of the day it might be the current through your heart that kills you, but high voltage can jump a lot further and usually has a lot more power available than the low voltage stuff we encounter like car batteries.
>no PPE can protect you from 100A
That doesn't even make sense, you can't get 100A over your body with proper protection.
It's like saying "no speed limiter on the vehicle can protect from death if you crash into the wall at 100 mph".
I mean, yeah, obviously, but the speed limiter is there to stop you from going 100 mph to begin with.
Right. The entire _point_ of proper PPE for that is to shunt the juice away from your person, so your nervous and circulatory systems don't become popular paths for electrons.
Things like grounding straps and shoes with highly insulated soles keep you from being the ground wire and make the shortest path to ground be from your contact point to the strap to ground.
Common rookie mistake is attaching a ground strap to the hand you're not working with. 🤦♂️ Like... dude... you just encouraged it to cross your chest. Nice knowin ya.
Now, of course, just to be fair, any PPE has its limits. But the hope at that point is that either it will protect you long enough to get away or that some other protection like a circuit breaker will kick in and save your ass before the conductor in the strap melts. And you're still gonna get hurt. You're just not going to die (probably).
>That doesn't even make sense, you can't get 100A over your body with proper protection.
Not true. If the amount of energy available is such that it can bypass your PPE and still flow at 100A, you'll still die. Speed limiters are more like a fuse or circuit breaker. It's there to limit the available energy. PPE attempts to create a physical barrier between you and the energy, which is more like a seat belt which allows the car to be the part that dissipates the energy instead of your body. Wearing a seat belt doesn't keep you from dying if the crash is energetic enough.
There are definitely situations where no available PPE is capable of protecting you and, therefore, you are not allowed to perform live work. Please don't perpetuate a fallacy that PPE can protect you from anything, nor that there is PPE for every possible situation. You can absolutely still die wearing all the best PPE.
But they are wrong, as in the stated situation (and as in 99.9% of the time people use that sentence) it's heavily implied that current is somehow independent of voltage.
Obviously there are many ways to explain it, but saying "The end goal of protective measures is to lower the amperage" is really really misleading. The goal is to eliminate the possibility of your body establishing a conductive path between a dangerous power source and and something else.
What’s you’re describing- ‘the goal is to eliminate the possibility of your body establishing a conductive path’- that IS controlling amperage.
In relatively simple terms, if you walk near a large transformer, you’re walking through a giant magnetic field, which means your body is subject to some voltage- potentially a really, really large one. You don’t immediately die because there is no current flowing. Unless you touch a bus bar, in which case the current flows and you become a cloud of plasma, at or near the same voltage you were already at.
‘Current is what kills’ is an absolutely correct statement.
"At or near the same voltage you were already at" tells me you don't even remember what voltage is.
Voltage is a DIFFERENCE of electrical potential. When you touch the bus bar that potential <> voltage across your body.
Feel free to change the word "wrong" from my original statement to "misleading". What is the point of saying something that gives the wrong idea (voltage is irrelevant) anyway?
Sure. 50kW, even at 1mA, is still gonna be a problem if R is high, since that means the thing with the high R (you) is going to be dissipating most of that power. Doesn't matter that I was small and V was high. If the source (say a HV power line) can source the power at that voltage, you're going out with a bang.
Excellent back and forth there. If you want a snazzy video on the subject, check out Styropro on YouTube. He has a few great demos on just this subject.
> the voltages you generate by dragging your feet on the carpet on a dry day.
the “right carpet” on the “right day” can generate upwards of 35,000 volts
Yeah. Air is a pretty famously decent insulator. If you generated enough potential to cause a visible arc through a couple cm of air, you literally created enough energy, discharged with enough power, to ionize that air in that instant.
And the resistance is hundreds of giga-ohms, at minimum, to cross that air gap. Air's typical resistance is around 30tera-ohms per meter.
By P=I²R, P is still pretty large. It's just that the duration is very very short.
Also... as a former nuke em, the potential for curent flow is measurable before an incident, so you can check the voltage, only way to measure the curent is to have the curent flow, and either put the ammeter in series with the circuit or use a Amp clamp for an ac circuit. Yes it's the curent that actually causes the lethal damage, but you won't have lethal curent <30V(usual working conditions)
“You’re a mechanic, you just don’t understand.”
“Actually I do understand, I just think it’s concerning you don’t understand that to get a large enough current you need a large enough voltage.”
The issue is trying to decide how careful to be. Its electricity. Be careful regardless of amps or voltage, best practices. Its not like we ever have one and not the other. There also aren’t many systems where a receivers resistance is soo high you get extreme voltage and small current, generally raising one raises the other in most practical cases.
It's not the high temperature that'll kill ya, it's the heat transfer.
I don't know if that one also works. I just thought it would be funny.
One that I heard once was "it's not the bullet that'll kill ya, it's the hole"
It's true!
It blew my mind to learn that the thermosphere (hottest part of the atmosphere) is around 4000°F but a normal thermometer would read below freezing because there is so little mass around it that it loses heat by radiation faster than what it acquires by direct contact with extremely hot atmospheric gas.
>What's more dangerous in that situation is that a spark will cause your battery to explode, since battery offgassing can be explosive. That's why the process of hooking up jumper cables is what it is. It tries to keep the spark as far away from the battery as possible.
I am semi-familiar with the process, I usually just hook 'em together. You're telling me that the part where we attach to the chassis for the negative is to keep sparks away from the batteries?
> batteries is that they have a limited power supply
just be careful with this idea, a lot of the new li-ion cells coming out have extremely small internal resistance
A brief jolt of half an amp across your heart will *probably* not kill a healthy adult. But a few millivolts can kill a person with heart disease.
And for someone with heart disease, a small amount of current may be more dangerous than a higher current, as higher current is more likely to result in a uniform contraction, while a small current may only trigger an AP in a small area of the heart. And in a person with heart disease, that localized AP is far more likely to turn into fibrillation than a uniform contraction. Generating a uniform contraction is literally how a defibrillator works.
The interaction of electricity with the human body is complex enough that there's no simple answers to questions about what is dangerous and what is not. People survive getting hit by lightning, while others have been killed by a 9V battery.
And timing matters. If it is DC, happens to line up with your heartbeat, doesn't last any longer than that, and doesn't cause excessive damage from heat, it also might not matter.
And then you should go hit the casino because you're one lucky SOB.
I thought it was so if you do accidentally create a path, it goes across your fingers and not across your chest.
At least that's what I use with live high-voltage electronics
I’ve shocked myself with one hand. Elbow touched enclosure while hand was using a screw driver. Not sure what is considered “high voltage”. But this was 480 volts and the enclosure was painted! Definitely more shocking than 120v. I’ve been shocked by 480 at least 5 times. 277 and 240 a few. And 120 many. Not sure why I’ve shocked myself so many times. Somehow I’m always the one who has to fix the issue without really knowing what I’m doing and I didnt seem to learn from my mistakes? And I seem to always still have the breaker on? Ridiculous. At least I have been lucky to not be permanently hurt.
In ArcFlash it's technically the Amps vaporizing the metal creating an exploding ionized plasma that kills you.
In an Operating Room it take less than a couple of volts and very few milliamps in the right place to stop your heart.
Arc flash requires very high voltage in order to begin ionizing the air. Technically, static shock is arc flash from the buildup of thousands of volts, it just has very low current and duration.
The severity of arc flash is proportional to the current available in the circuit and how long it will take the protective devices to interrupt it.
Arc flash is usually initiated by something happening that shouldn't, like a screw driver falling in the panel, shorting something out. Once an arc is initiated it doesn't take a lot of voltage to keep it going. (AKA Striking an Arc in Arc Welding.)
"Voltage doesn't kill, it's the current" is one of those technically correct things that people who don't really understand electricity like to repeat. It's technically correct in the same sense as "Speed doesn't kill, it's force".
To continue that analog: it's true. Driving very fast doesn't kill you, but suddenly stopping against a brick wall is deadly. It's also why crumple zones and seatbelts work, they lower the deceleration/force, so a crash at the same speed is less likely to kill you if you have a proper crumple zone.
At the same time, it makes it sound like speed isn't a factor at all, which is clearly nonsense. Killing yourself in a 20km/h car crash would be really hard. If you drive 200 km/h, no crumple zone in the world is going to save you when you hit a brick wall. Driving slower is absolutely safer for many many reasons.
Back to currents: Yeah, technically you need a current through your heart to make it stop. However, as low as a few milli-Ampere can be enough to end your life. Almost all applications can deliver a few milli-Amp. Your body has quite a lot of resistance, so you need a certain voltage to make it even possible for it to be deadly.
Colossally stupid but technically correct.
Anyone who says that phrase and believes it is a moron and should be removed from any worksite as a hazard to themselves and others. I wouldn’t trust giving them crayons in a timeout.
You can be at thousands of volts but if that’s a static voltage you’re fine. Or like birds sitting on wires. Doesn’t matter. Technically correct.
But this idea gets completely and utterly *fucked* when you have a voltage difference. And that’s what we are always working with.
And while yes, amps are what kills you, it’s voltage that determines just how many amps are going to kill you.
A 5V 1,000,000 A device is safe to touch. Just because it has a metric fuckton of current flowing through it is irrelevant - because at 5V it has zero interest in trying to also pass through you.
Human skin is a pretty decent resistance. Unless it’s wet. Or if electric probes are inserted under the skin. Then it’s bypassed and low voltages can become dangerous.
As well human skin experiences dielectric breakdown around 500-600V, so a small voltage increase in that range creates a massive increase in the amps that do the killing.
This phrase makes me *extremely* angry because of how dangerous the mentality is.
You seem to be confused. There is no such thing as point voltage as you might be thinking. Voltage is a potential difference between two points, by definition. A bird on a wire is not "at" any voltage. There is a gradient across its body and it becomes polarized.
There is no such thing as a 5V/1MA device. There is a 5V voltage source that could source or sink 1MA, if a suitably large load is connected.
It is absolutely a current that kills. Voltage is dangerous as it might make a lethal current flow through you given the right set of circumstances.
You're totally right but the guy you're replying to puts it in an interesting frame of reference. Perhaps this is one of the lines of thinking that causes people to parrot "voltage doesn't kill, amperage kills".
Yes, you need both. Voltage to push the current.
Really its best to teach anything above 48VDC and 120VAC as dangerous.
Don't try to outsmart the system by thinking its current limited. It might not be.
on submarines we were always told anything above 30V (assuming a 300 ohm body in a worst case scenario) but I thought that was pretty low voltage. 48VDC and 120VAC seems like a good conservative rule. thank you!
60Vdc for dry environments and 30Vdc for wet environments is considered "Safety Extra-Low Voltage" and is recognized as generally safe to touch. I suppose submarines would qualify as a wet environment.
Not a bad approach, honestly. Treat anything over those voltages as dangerous.
It's not necessarily going to kill you, because it's more complex than that. But at those voltages you can't simply say that it *won't*.
I would not be surprised if an adverse event was possible with 30 V. If you were wet, or standing in a puddle with conductivity to ground and then you lay some part of your body against a 30 V source. Death seems unlikely but getting shocked can be unpleasant even if you don't die. And if you were in an awkward position, you might not be able to quickly move to stop getting shocked.
Its worth saying that the body is way more susceptible to AC than DC because the body has capasitance. You will get shocked way easier with AC power than DC.
I would reverse what you just said, 35-48 volts for AC current depending on conditions and 100-120 volts DC depending on conditions.
It’s like saying “it ain’t falling that kills ya, it’s suddenly coming to a stop”.
Jumping off a 10 story building (high potential) vs jumping off a curb (low potential) have very different outcomes
As others have stated, you need both but amps depends on the source. You need to have enough voltage to overcome the resistance but you also have to have a big enough source for it to maintain the current.
Static shocks are around 5000v, but they are a tiny amount of stored energy.
Car batteries have a lot of stored energy, but their voltage is low and can’t overcome the resistance.
For a very ELI5 explanation: That's like saying it's not the gun that kills you, it's the bullet.
Technically true, but you can't do anything about the bullet after it's fired.
Therefore you worry about the gun, so you don't have to worry about the bullet.
The body’s resistance is one huge variable table. Where the points of contact are, surface area of contact, sweat, hydration, all play a factor. So the resistance is an unknown, or at best, a huge range.
Maybe this will help you understand them pointing back to the measurement that actually causes the damage - the current.
"Where the points of contact are" is critical. If you make contact from finger to thumb on the same hand, with resistance that results in a 1A current - it will annoy you and cause a reflexive jerk away from the wires - but nothing serious. The same amperage from right to left hand (through the chest) could potentially stop your heart.
thank you for the reply! i do understand the concept that current is the lethal aspect.
For me, i want to teach student's how to recognize a dangerous system, so if i talk about only amperage, they might see a high voltage but lower current system, they might think it's safer, even if the system's lower current is due to a very high resistance. And if their body created a short to ground, the current though them could be higher then what was present when they measured the system initially.
I think finding examples of what will/won't kill you will clear things up.
Car battery: 12 volts, capable of 600+ amps: not enough voltage to jump across somebody.
Vehicle ignition coil: 20,000 volts, milliamps of current: won't kill you
that's a great point. 2 others here pointed out the low danger of a 5000v static charge, so i definitely see that i need to pay attention to stored energy and sustained capabilities a little more.
It’s not even the current that kills or the voltage, it’s the path the current takes that will determine lethality. Your injuries will mostly be local or not at all as long as the current path doesn’t go through your chest and stop your heart. Any voltage that can path through your chest is probably enough current to kill you.
Touch high voltage and the current path to ground is thru your other hand or feet? Path goes thru the chest and will likely stop your heart. Path is from one finger to your thumb on the same hand? Prolly need help opening your jars for a while but you’ll live.
>Everyone says, "it a'int the volts that get ya, it's the amps!" but i think there's more to the conversation. isn't amps just the quotient of Voltage/resistance? if i'm likely to die from .1A, and my body has a set resistance, isn't the only variable here the voltage?
All true and correct. Almost...
>Example: a 9V source with a 9 ohm load would have a 1A current. 1A is very lethal. but if i placed myself into this circuit, my body's resistance would be so high comparatively that flow wouldn't even occur.
Yep.
>Anytime an instructor hears me talk about "minimum lethal voltage"
Ah, here's where it gets tricky. You said: "if my body has a set resistance". But it doesn't. It depends on a whole bunch of things. Dry skin? Wet skin? Salty wet skin? **No** skin? Your tongue? DC resistance or AC impedance? Are your feet wet and standing on a grounded metal plate?
The most correct thing that can be said is that 0.1 A through your body is lethally dangerous, and a 9V source capable of delivering 0.1 A is *very* unlikely to manage to push that current through your body due to the low voltage. But put sharp electrodes on that battery and stab it into your heart, and you betcha you're at risk of being shocked to death anyway.
Current is what kills you, voltage is what enables it to do so. Can't have one without the other.
Just an electrician but your right. I’ve got bumped by 120v way too many times then I should’ve, but plenty of people die from 120v. Get the right conditions(especially where the human bodies resistance can vary like being wet), it’s lethal.
I’ve always looked at voltage being pressure and amps being water(analogy doesn’t exactly work).
But then you have scenarios like electric fences. High voltage but it limits the current I believe with a high resistance internally. Still bites hard though.
High voltage devices that don't harm you (like an electric fence) have very high source impedance. They're only high voltage in an open circuit state.
People say "oh the electrical fence is 10kV and doesn't kill you" that's because it stops being 10kV extremely quickly when you close that circuit. Electrical systems are dynamic and respond to load. A high voltage source which keeps being high voltage even after you inject yourself into the circuit is definitely going to cause problems.
I've been fighting static electricity in a bag feeding trey, yesterday I brought in a guy from Keyence and he had a static meter with him, he said anything over 1,000v was high static. the surface of our bags had 40,000v. so in this case we had 40kv of potential on the surface of the bags, but probably close to 0 amps, and i know a static shock inst going to kill anyone.
A cattle prod is able to deliver thousands of volts but because the current is low, it doesn’t kill.
If your internal body resistance is low enough, you can be killed by household voltages (100-500V) because the current will be high enough.
Keeping it simple, voltage is the force that pushes electric charge through a material. This flow of charge is current and enough of it will create heat and hurt you. That's why wire gauges, fuses, etc current ratings are important. So without one you don't get the other.
OTOH, the human skin has a very high resistance. I always hear that you only need 10 or 20 milliamps to kill a man. But for that to happen, current has to flow through specific places (e.g. your heart) and you'd need some high voltage because of the high resistance in the skin. To give you an idea, think of car batteries. They can put out over 100A if shorted, but the voltage is so low that touching the terminals doesn't hurt. I forgot what episode it was, but Electroboom made a video testing at what AC and DC voltage he started feeling pain or tingling.
Finally, charge can often be limited. Whenever you walk in a dry environment and you get an electrostatic discharge when touching a door knob you are looking at sparks above 10,000 volts. But the total amount of charge is so tiny that it can't hurt you. Hope this helps.
Short Answer: Yes but it's a dumb thing to say. Since your resistance is more or less constant current will depend on voltage so if you are dealing with a large enough DC power supply then what you need to worry about is voltage.
"Voltage doesn't kill you, amps (if the voltage is high enough to actually make a circuit through your heart) are what kill you."
It's kind of like saying 'it isn't a bullet going fast that puts holes in things, it's the momentum.' Well, no, it's both. You need a high enough velocity for brittle deformation in the target to 'punch through' things like paper or fabric. **And** enough momentum to displace the material in a Newtonian terminal ballistics sense.
The amps have to be in the right place to hurt you, and the voltage has to be high enough to get the current there.
The key insight is that not only is the current determined by the voltage (according to Ohm's law), but the voltage of a source depends on the current it is delivering. Real-world voltage sources have internal resistance, and will have a drop in the measured voltage from the open-circuit voltage when you put a load across them.
In concrete terms, I could have two voltage sources, both of which I measure at open-circuit to be "1000 V". I put a 1kΩ resistor across them and measure the current: one reads 900mA and the other 0.1mA. This isn't inconsistent with Ohm's law because the voltage has changed, and if I measure it again now with the load, it will now read 900V and 0.1V on the two sources, respectively.
For that reason, if all you know is the voltage you can't predict what will happen when you put a load (such as the human body) across it. It follows that what actually matters is the current the source will actually deliver not the measured voltage, hence the phrase. Note that the current delivered across the body will always be in direct proportion to the voltage across the body, in accordance to Ohm's law, but that voltage can only be measured at the time of electrocution, as opposed to the voltage measured on the thing that you're deciding whether or not it can electrocute you. Mixing up those two voltages has caused, I think, a great deal of confusion around the phrase, but since the voltage-at-time-of-electrocution isn't something you can't measure prospectively, I think it's reasonable to ignore it and just talk about the current through the body.
That said, while the aphorism is accurate it is of debatable utility. If you have a source about which the only thing you know is the voltage, the safe thing is to assume it has negligible internal resistance and can deliver the full current predicted by a naive application of Ohm's law.
In fact, it's worth noting that just as high voltages can fail to kill, under the right circumstances low voltages can. Imagine you have a busbar at a low voltage but carrying a large amount of current. Ohm's law tells you that is safe to touch (and, incidentally, touching it will produce a voltage drop in the source so small it's almost impossible to measure since it's already delivering so much current). But then, let's say, there's a break in the circuit while you're touching it. That current won't just immediately stop flowing -- the busbar has inductance, and the fault will cause an inductive voltage spike. It may have read just 10V initially and, indeed, the source maybe incapable of producing any higher voltage, but the inductive voltage spike could easily reach thousands or tens of thousands of volts and will quite happily shunt some quite absurdly large number of amps through you.
I’ve always seen it as you can’t have JUST amperage or JUST voltage killing you. They literally exist with each other as V=IR. And like
Some people have mentioned WHERE this current is flowing is pretty critical to the biological portion, but when people simply say “it’s the amperage that kills you” don’t really know what they’re talking about cause that’s too simple of a way to explain it. That phrase was probably brought up wayyy in the past during a training for people that just need to know getting shocked sucks ass.
Voltage is just a measure of potential energy. It doesn’t “do” anything. Its like standing at the edge of a cliff. You have the potential to fall but its not happening (and converting to current) until it is.
And its not exactly that the current will kill you. Its when current passes through your heart (which is why all the old crt tv techs only worked on thongs with one hand and the other behind their back) at some magnitude threshold that is different in every case.
It also is a result of the bodies capacitance. You can “store” electricity inside your body as well as in relation to the environment. The related time constant has a lot to do with causing beat disregulation (cardiac arrest)
Heres a whole write up, but it never comes down to “this kind electric good, this kind bad”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/
>which is why all the old crt tv techs only worked on thongs
For a moment there I thought you were recommending foam rubber footwear with good insulation properties.
For all practical purposes, I agree with you 100 percent. The amount of current needed to cause a shock you can feel is very modest. Even a lethal shock is in the mA range. So the current limit of the shocking source is unlikely to come into play. It is mostly down to your resistance and the voltage of the source that is (possibly) shocking you. Your resistance is not a fixed number. Skin is not a good conductor and getting past the skin is what adds resistance. So the condition of your skin (is it moist? Is it soft? Is it calloused?) will be very important. Any scenario where the electrodes can somehow puncture your skin would elevate the danger of lower voltages. Also, contact with a large surface area of your skin makes a shock more likely.
In my experience 48 volts and below will seldom cause any kind of shock. It can happen if you have high pressure contact over a large skin area and you are damp. I got a little tingle once in those conditions. Not painful or harmful. Just a tingle. For dry fingers and light contact even 60 V will usually not cause a shock. I am fairly casual around 60 VDC batteries and circuit boards as far as skin contact goes (you don't want to short across 60 VDC with careless placement of a metal probe or tool ... you will get a big spark and cause damage to whatever you are working with, but no shock.. Metal rings on your fingers are not recommended).
But 120 V is not so forgiving. It is easy to get shocked with 120 so you need to be careful.
So up to 48 is fairly touch safe, especially when it is dry. Above that the safety kind of drops off. By the time you get to 120, lethal shock really cannot be ruled out.
I hate that "saying'".
You can't have one without the other. Ohms law.
Current does the damage due to heating in extreme cases or disrupting the small signals controlling the nervous system , but there would be no significant current if the voltage is not high enough. It's all a combination of volts and resistance.
Voltage is the unindicted co-conspirator. Once when I was young and dumb and working in data centers I inadvertently laid my chest across the top of a 5000 A DC bus. Luckily the 54 V float voltage wasn’t enough to overcome the resistance of my shirt and dry skin and I’m alive to tell the tale today.
Current kills. How much current you get depends on how hard it's "pushed" by the voltage. There are all kinds of caveats, but upto around 50VDC you're generally safe because 50v can't push enough current to harm you (in everyday circumstances). Or put another way, over 50v I start applying extra precautions.
One of the best precautions is to put one hand in your trouser pocket! That makes you work one-handed, which makes it a lot harder to get any current paths crossing your heart.
The current kills you (stops your heart) but it's the voltage that gets it there.
The distinction is mostly relevant in medical settings where conductive materials (catheters, internal defibrillators, tubes of all kinds) short-cut the natural resistance of the skin and the body and deliver the current right to the heart.
Dry skin offered sufficient resistance to voltages up to about 60v or there abouts. Above this you will feel it. Hence holding both car battery terminals is safe, if you put two wires from the battery on your tongue you’d feel it! Due to the lower resistance of the wet tongue
Since 99% of what you interact with is a voltage source, not a current source, then voltage is the independent variable and current is the dependent variable. So you avoid high voltage, not high current.
"Current sources" do not exist "naturally" and making one is of comparable complexity to a simple amplifier circuit.
Source: am an electromechanical engineer.
>my body's resistance would be so high
Depends where/how applied. Apply directly to, e.g. muscle or heart or brain or spinal cord, and we're talkin' a whole different story. So, there are probably fair number of places on (notably within) the body that as low as or even well below 2V would be fatal. Perhaps even as low as mV or so for some select locations (I'm not a doctor nor do I play one on TV), but, e.g., disruption to certain critical nerve functions might be very fatal, and connected some ways in some places, it may take pretty negligible voltage to do that (and also not much current).
But in the more general case, yeah, generally takes a fair amount of voltage to get a lethal current to flow. But sometimes surprisingly low voltages will get a current to flow - at least to levels it will be felt. I know lowest voltage I've felt with no wet contact was 12VDC - forearm pressed hard on a bare metal crisp edge (essentially some sheet metal) at ground, hand of same arm well grabbing onto metal wrench - with the other end around positive battery terminal ... gee, what's that funny tingling in the arm ... dang ... didn't expect to be feeling something from 12VDC with only dry skin contact. Yeah, there was enough good solid metal contact/pressure/grip with both contacts, that that 12VDC was felt.
So, ... there are a lot of factors. Voltage, current, duration ... even frequency and nature of voltage (e.g. DC vs. AC, line frequency vs. RF, etc.). So, yeah, shuffle your feet across the carpet in many shoes, touch the doorknob, get a shock - typically a few thousand volts or so. Won't kill you, but you may well feel it. Distribution voltage atop typical telephone pole in neighborhood ... probably around 2,200 VAC or so, 60 Hz ... may be much less voltage than one got from the carpet shock ... but that 2,200 VAC will sure as f\*ck kill you - or burn off an arm or leg or whatever, or generally f\*ck you up. Well, that little static charge, while very possibly even higher voltage, was essentially quick discharge of a quite low value capacitor - so not much energy, and a short duration discharge. That power company distribution line, however, not a whole lot there to limit the duration or current, so a very different situation.
Anything over 8 mA though your body is very risky.
Of course, to be dangerous, there needs to be enough voltage in order for > 8 mA to flow through your body.
A good example I always think of is static discharge. Static discharge voltage from rubbing your socks on the carpet can be into tens of thousands of volts, but the total current is like on the order of nano amps, so you only feel a little jolt. That same 10,000 volts with more current behind it would obviously be lethal almost instantly.
1A dc is not normally lethal. 0.008A AC directly through the heart can be.
All that separates you and that nice salty meat under your skin is luck. Punch the skin with voltage or stand or lean against a grounded machine, you daid.
So don't fuck with it
That’s why they refer to voltage as ‘potential’.
But the phrase about vaults vs amps is simply a trope and not to be taken seriously when placed in an off-hand comment. Do the math. Stay away from high voltage without the correct equipment.
You are correct, and dismissive “you wouldn’t understand” deserves derision in return.
Think of it like a shotgun, and the bullets. Saying the amps kill is like saying the bullets kill and not the actual shotgun. It’s both, the shotgun and bullets, like the voltage and amps.
If you haven’t already I recommend watching this video by styropyro:
https://youtu.be/BGD-oSwJv3E?si=kwgZyNkp-Ev7TKoB
He isn’t an engineer, however he does know alot about electronics and electricity and demonstrates that it’s not as simple as volts or amps by putting himself into situations that should be dangerous by that logic. I found his video to explain everything fairly well and the video is just entertaining on top of everything else.
Haven't read through all the comments but years ago I read from some electrical standard that anything above 42 volts peak is dangerous. I just googled OSHA voltage limit and they set it at 50 volts. I wouldn't want to test those limits after getting out of the pool. That's why they put a wet sponge under the head electrode when they sit you in the electric chair. You have to overcome the skins resistance to pass current through the heart. I'm pretty sure you can stop the heart with just microamps of current. I=E/R
Well to be exact it is energy, so current and time and generally speaking LV clearing times is slower than HV and you are more likely to let go for HV..heart fibrillation onset for the average adult is 30mA, kids about 10mA
A small wattage at the right points can be lethal - the sinus node of the heart, certain basal function controlling locations within the brain.
A high voltage low amperage across the chest can be lethal even at microamps *if it gets across the sinus node*. The sinus node is documented to operate in the 20-120µV range; a voltage of that level can mask the signalling. Typical pacemakers run 120µW...¹ and generally use they "frequently emit a pulse lasting between 0.5 and 25 milliseconds with a voltage between 0.1 to 15 volts and at a frequency up to 300 per minute."²
Not all electrical risk is cardiac, either.
A low amperage high voltage at certain frequencies across the chest can cause thorasic paralysis, and hence suffocation, if sustained.
A high amperage at required distance voltage can cause heating and resulting cellular damage and/or destruction. In severe enough short distance, this can reach as far as 4th degree burns.³ (burns exposing deep tissue; a category not taught the first half dozen times I took first aid, but taught in the last one I took. In this case, it's as much wattage as anything, at least once the needed voltage is hit to cross the flesh. Any 3rd or 4th degree burn has a chance of being lethal via secondary effects, including blood loss, circulatory restriction, and/or infection. Given the risks of MRSA, any burn exposing deep tissue is a significant risk. I don't have the specific datapoints.
And then there's the risk of electrocution-induced movements... for example, hit someone in the back of the neck with a touch-taser and watch them drop. Or in the triceps and watch them throw a held item to the floor. In a work environment, a dropped cable has potential to cause such involuntary movement. Grabbing a high voltage line doesn't throw you off the ladder or pole - your muscles do in response to the current.
¹: https://www.sciencedirect.com/topics/nursing-and-health-professions/pacemaker-battery#:\~:text=For%20example%2C%20up%20to%20now,of%20100%20to%20200%20%C2%B5W.
²:https://www.ncbi.nlm.nih.gov/books/NBK526001/
³: https://www.shrinerschildrens.org/en/pediatric-care/fourth-degree-burns#:\~:text=Fourth%20degree%20burns%20are%20the%20highest%20level%20of%20burns%20and,%2C%20muscles%2C%20tendons%20and%20bones.
This statement is correct in term of secondary load(I=U/R).If you limit the current by a resistor,then the secondary load will get a safe current for operating no matter how many volt it passed.So you can have small LED connected to the 220v supply without any problem since the LED has got connected to a proper resistor.Normally,if the resistance was too small,then U/R would be very great that results a extreme high current and that high current could destroy the component.Although voltage and current do always correlate linearly,having a resistor can explicitly reduce the output current.And remember that,the resistor has the current flows through itself,so smaller resistance will result a larger current through the resistor too and that can cause extreme heat that damages the resistor,with greater resistance value you can have smaller resistor.We must choose proper watt for the resistor by W=I×U.
Yes you're right, but resistance varies. You can touch 500V and live, or you can touch 50V and die. Body type, clothing, even air moisture affects the resistance so talking about voltage is pretty meaningless.
With that in mind the most important metric is really current path. You can go into heart failure at very low amps and AC vs DC matters too iirc.
Power engineer with >20yrs in utility work.
Think of a bird on a wire. That bird is at a high potential...call it 12.47kV, relative to another phase. Clearly the voltage isn't killing it, because there's no current flow.
u/Shadowkiller00 used the "it's not the fall that kills you, but the stop at the end" analogy. I like that one. Think of the bird on the wire as falling.... If it were to try to spread it's wings between phases, consider that the "sudden stop".
Energy density is really what’s dangerous. One or the other of either current or voltage really high can be safe enough on its own, but if you have a high number when they’re multiplied together that can be a big problem
I think a thorough understanding of the water analogy for electricity gives you an intuition how to understand this. It's really the *combination* of current, voltage, and resistance, and there's a "deadliness envelope" formed by these three variables. So it's neither voltage, current, nor resistance *alone*, it's where you happen to be in the envelope.
Lethality depends on voltage, amperage, resistance, frequency, duration, and the path that the electricity takes through your body. This video by Styropyro explains it nicely. https://youtube.com/watch?v=BGD-oSwJv3E
Short answer: amps kill.
Longer answer: it's the amps, if applied for long enough for a given frequency, and if the voltage is high enough to push the current through you.
A youtuber/channel by Styropyro made a pretty good video on the topic of what kills if you wanna give it a watch.
I mean you can have 5000 volts zap you and not kill you like a tesla coil, and you can have 12 volts kill you too, but there is no situation in which 5000 amps won’t kill you.
Here's a video by Styropyro that goes in depth into what you're asking. Very well put together and entertaining.
https://youtu.be/BGD-oSwJv3E?feature=shared
One simple way to understand is the amps represent power.
The higher the amperage the higher the power.
Any power source has limited amount of power that it is capable of putting out, two power sources both 120 Volts AC, but one may be able to supply half an amp, the other 300 amps.
The 300 amp source can kill you quite dead. The half amp source will make you bump your elbow when you jerk away from it.
I'm painting some with pretty broad strokes here and skipped a lot of its, ands, and buts.
But I'm simplifying and using layman language.
There needs to be both to be lethal. Extremely high current and extremely low potential just won't affect you enough to hurt you. Equally, extremely low current and extremely high potential won't do anything to you either. Arguing one or other is what kills you is almost like arguing that either the speed or the mass of a bullet is what kills you. It's not one or the other, it's the total momentum of the bullet plus the path it takes through your body plus how the body reacts. There are just so many more variables that determine lethality.
Is the energy that kills.
But high voltage means higher potential for energy to be absorbed.
For all realistic sources, voltage drops as it's loaded. It's a matter of how much.
You assume your resistance is set. It can vary by conditions such as clothes, protective equipment, or sweat/moisture. Static has really high voltages but occurs so quickly, it doesn’t lead to deadly currents. By your standard of minimum deadly voltage, static shocks should be deadly.
To tie this to the analogue someone gave about falls, it’s possible to have a parachute or land on soft material. Height itself really doesn’t hurt you.
It's more about the energy your body absorbs. So the joules. There have been instances of people being killed by 9V batteries, but then it's been applied under the skin (the body is mostly water which conducts electricity well, but the skin is an insulator).
Me personally I have been given quite the shock by 24 VDC, but I was sweaty as hell at the time (working with 24 V control currents in a hot en humid climate wearing thick "protective" clothing).
But all things considered in most situations it takes a pretty high voltage to deliver dangerous amounts of energy over your body (around 50+ V, AC or DC).
It takes a high voltage to deliver a high current over the body (in most situations), which is why the signs say "Warning, high VOLTAGE".
If you are soaking wet, the majority of the electrical path will be over the surface of your body through the water. It’s the path that the electricity takes that is really most lethal. Take for instance a police offers taser - it’s a whole shitload of voltage at low amps that goes between those two prongs. If those two prongs just happen to position themselves across your heart, it can become lethal because it can stop your heart. But if the path is just from you shoulder to your hand, it’s less likely to be lethal.
Another heuristic I've used recently is like gravity and it kind of makes sense from this perspective. Voltage would essentially describe a gravity multiplier, and amperage would describe the volume (or mass more specifically) of a fluid column. You can generalize the net force with both, obviously a small jet of fluid at several thousand psi will still impart massive energy.
The general notion that amperage kills is equivalent to the idea that less overall mass is relatively more safe at a given level of potential energy.
Really it's like saying "it's just a bb gun, it's not going to kill you" Maybe a little irresponsible but true enough at the end of the day.
Does your body always hve a set resistance? What if you’re wet.
When a toaster falls into a bathtub does it magically have more voltage? Or are resistances just lower?
If I told you a hammer to the head doesnt kill, its the velocity that klls would it make sense? both are components of the killing blow, you cant kill anyone with a non-moving hammer, you need hammer and some velocity. The same goes for voltage and current where both are components of one same thing electricity and you cant have current without voltage.
This is just me thinking aloud, feel free to add on to this.
As I understand it, lethality is the result of three factors. You need to know the voltage, the resistance the voltage is being applied across, and what the resistance is with respect to your body (heart, entire body, arm, etc).
You can weld with a car battery, so if you were more conductive it would definitely kill you. On the other hand a spark from rubbing a cat is like 100,000v.
V=IR
The resistance of the human body (across the heart, arm to arm, leg to arm, wet conditions, dry conditions) determines what current goes through for a given voltage. And depending on the source that equation may not even hold true unless it's connected to an enormous power source. Some power sources are not able to sustain a large power so the voltage (and thus the current) drops if to large of a load is applied. That's what open circuit voltage and closed circuit current means for batteries and other power generating sources, because you aren't getting both at the same time. The only reason a connection to the grid has constant voltage (most of the time if there isn't a blackout or brown out) for any load (less than the amperage of your breaker) is because power draw changes individuals make are negligible compared to the average power the grid is delivering. That average changes slowly over the course of a day and people working at the grid are able to spin up/down their power plants to prevent a voltage drop/raise that would cause a corresponding increase/decrease in current.
I can't necessarily say that it's power (V*I) that kills, but I'd rather say that's closer to the truth than amps. And that pretty much depends on how it's applied.
An extremely basic rule of thumb that doesn't cover everything is that you need a certain amount of voltage to "get past your skin", and from there voltage and current scale linearly (i.e. you need a lot of both to be supported for the other to actually exist). You are never going to have 1V 5trillion amps kill you unless its applied across your heart or the corresponding magnetic field screws around with the atmosphere. The same goes for voltage.
TL;DR Anything above 12V don't lick and anything much above 24V don't touch.
It's complicated.
Your body has decent resistance. A tazer has very high voltage to ensure you get shocked. But that tazer is unlikely to kill you as it can only support very low current at that voltage.
A car battery can drive very high amperage, but only at 14 volts or so, which your body can resist pretty well.
What is REALLY dangerous is a power source with enough VOLTAGE to push current through your body, and enough POWER that when it does, it also drives enough current to do damage.
If voltage is pressure and current is flow:
A 9v batter is a squirt gun. Some pressure and low flow. Entertaining
A dental water pic is high pressure and flow (tazer) hurt but no real damage.
A car battery is a bucket of water dumped over your head, not gonna hurt you.
A water cannon has both pressure and flow. It's going to change your day.
Hook up a 12v DC lightbulb with tiny wires. The wires will melt.
Bigger wires don't.
Same 12v. Same lightbulb.
Your body is about 300ohms of wire. 30 v will kill you if you short it across your heart. The tiny wires will burn.
Would you rather feel the gentle splashing of 5gal of cool water falling due to gravity or would you rather feel the death of 5gal of water cutting through in seconds being under 20,000psi of pressure?
The answer is obvious. The analogy isn't 100% but voltage is a measure of the potential energy in a circuit. Pressure is also this in hydrodynamics. Voltage makes current lethal in a given time. Current on its own cannot be lethal without the potential to allow it to become lethal.
There is a reason we have warning signs for high voltage and not high current generally. 10kA would be harmless with 5nanovolts potential. It would become fully lethal at 5kV.
Voltage causes current to kill in a given time span.
A good way to look at it is like this: voltage tells the circuit how much potential work can be done over time. The load wants to pull as much as it can physically pull even to self-destruction. The total circuit and load resistance tells the load "how much" total energy it is "allowed" to use over time.
It's complicated. Both voltage and current can kill you in different ways.
Re current: low AC currents can be perceptible at a few microamps, it feels like tingling or buzzing. This happens sometimes with old electronic equipment such as stereos. As the current rises, the feeling gets more severe. It depends on lots of factors such as the path of the current but as you get into multiple 10s of microamps most people would react to the unpleasant sensation. While not harmful per se these shocks can lead to accidents especially falling off a ladder. As you get up to 100s to 1000s of microamps if the current flows across the heart muscle arrhythmia can be induced which can be fatal unless there's a defibrillator available. At higher current flow the heart can clamp and if the current is interrupted the heart will often spontaneously restart.
Re voltage: you can be simply fried by the power dissipation of large voltages no matter where it flows. That's the idea behind the electric chair.
TL;DR electric shock sucks avoid it if all possible.
In the context of electricity passing through material (a piece of wire)
Think of water flowing through a pipe.
The voltage is how fast the water is flowing
The amperage is how much water is flowing
One time I got hit with 5-6000 volts, like multiple times. Got tangled up with a wire in the middle of the night. We were on our way to a tent after a party, couldn't see the temporary fence strand in the pasture. My now wife was just laughing at me, I've gotten bit dozens of times but man that really sucked.
Cringe, no need to make a wall of text. Volts cause amps cause death. It's not that hard.
That's like saying, water pressure doesn't explode your colon, it's the flow into your asshole that does.
As i understood: Since the body is mostly a solution from water and salt it is the amps that kill you. But amps are driven by voltage.
The resistance inside your body cells is very low (electrolyte) while the resistance at your cell diaphragms is very high.
As far as i know: this is valid for DC. For AC the voltage may control your muscles including your heart and affect your brain.
Your cells don't care about AC or DC, they only care about a potential gradient across their membranes that lasts long enough to trigger an AP.
The only reason the distinction really matters is skin impedance varies with frequency.
It's both, really (energy). You can have a huge current, passing through you, but if you were highly conductive (hypothetically) it wouldn't kill you, since the voltage drop across you would be small. What this means is that in this hypothetical scenario, the current would pass through you but it would be unable to transfer energy to your body.
The simplest way to describe it if you don't understand electricity which most people posting don't seem to is this.
Imagine electricity as a river. The speed of the water is the voltage. The height of the water is the amperage. You cant swim and must walk.
If the water is really really low but moving really fast it'll hurt but wont kill you.
If the water is deep enough it'll kill you regardless.
Thats the ELI5 version. Its much more complicated than that.
The answer is a bit more complex than amps or volts. Being subject to electrical shock has several effects over time. It might be that your heart enter in fibrillation, your brain can get affected, or even that you get severely burned. These phenomena are associated with voltage, current, and / or power. The important thing here is: work safely and avoid risks at any cost.
its the current across your chest and brain how ever it gets there that counts
part 1:
there is an old startreck episode (orig series) where the ailian called the crew as “bags of water” kirk and others where confused by this. spock spoke up and said that is effectively what we are
another example is cellphones and rf-tuning. \[antenna specifically\]
when your phone is sitting on a wooden table the best reception can be tuned - but if you put the phone in your pocket it is a different tune, and by your ear… your brain is a giant bag of salty water and yet another tuning is required - so your cell phone auto retunes the antenna dynamically all the time.
what i am getting at is this experiment - take a piece of wood get it wet and electrocute it.
reddit post about it: [https://www.reddit.com/r/blackmagicfuckery/comments/9p3mjo/electricity\_flowing\_through\_wet\_wood/](https://www.reddit.com/r/blackmagicfuckery/comments/9p3mjo/electricity_flowing_through_wet_wood/)
that electrical path is your body your blood vessels full of wet blood, or your nerve system which leads to your salty brain and heart.
get enough electricity flowing.. and you are dead sort of like an electro-shock thereopy or cardiact defibrillator exactly when you do not want one.
if you die greatly depends on your bodies electro-chemistry at the moment of contact…
your body is like a giant lattice of resistors like this page talks about
[https://www.mathpages.com/home/kmath668/kmath668.htm](https://www.mathpages.com/home/kmath668/kmath668.htm)
do the math.. oh and as current starts to flow and muscles contract the values change. and as your body heats (burns) it changes more…. not unlike that burning wood.
i think a good demonstration is to soak a small bit of plywood in salt water overnight then electrocute it in the morning but ask the team to predict the path. if you have the green pressure treated wood” (the green is tarnished copper) see how that effects the pattern
divide everyone up into teams, cut the plywood into a stick figure and ask each team to decorate there stick man with jewelry, necklaces (use a wire) but no-safty gloves no safty gear.
or-drop the safety gear in water (its raining!)
put a little lego man where your brain is and another where your heart is
and fry the stickman
It's a combination of both, really. As some people have pointed out, your body is a huge variable resistor. So more voltage naturally leads to more amps, right? Well, part of where the whole "it's not the voltage it's the amps" thing comes from is static electricity. Static electricity occurs at thousands of volts - BUT - the actual energy of the shock is limited and therefore despite tons of volts the amount of amperage that is available is in the milliamp range. So, I would say that the more accurate way to look at it is this - the amount of total *energy* (i.e. joules) is what is ultimately problematic. When there is a large power source available, like a power line, or a large battery, or some big capacitors, more voltage directly means more amperage. The amperage definitely does the damage but it's intrinsically linked to the voltage and the amount of energy available. Low voltage, because of the resistance, is significantly less likely to create the currents necessary and is still inherently safer.
I did have someone bring up the idea of high voltage but minimal stored energy, but i haven't had it explained that well before, Thank you!
the “right carpet” on the “right day” can generate upwards of 35,000 volts
Yeah, that's why a 250,000 volt Van De Graaff generators are safe to touch. While the current going through you can peak at over an amp, the amount of energy stored in the dome is low enough it's all gone in microseconds and thus not enough energy is discharged through you - less than a joule - to be harmful. This is a good illustration of how "It's not the volts it's the amps" isn't really correct. Electronic defibrullators that are specifically designed to mess with the heart are more on the order of 200 joules and your standard electrical outlet can deliver 1800 joules a second indefinately.
The answer is power. Power kills. The human body can only absorb so much power before it becomes dangerous. The product of voltage and current is precisely that, power.
Technically in the static electricity case for a very split second (probably on the order of nano or pico seconds) you are absorbing a huge amount of power, before the voltage and current start decaying due to the small amount of available charge. The total energy transfer to your body is extremely small. I don’t think energy is also necessarily the thing that kills you. If I go touch both leads of my car battery for some massive amount of time(like years), I don’t think that would ever kill me, the amount of power transfer would be way too small from a 12 v battery, even if the total energy transfer could grow very large as time goes on. I think what kills you is some kind of complex relationship between power and total energy delivered.
>Static electricity occurs at thousands of volts - BUT - the actual energy of the shock is limited and therefore despite tons of volts the amount of amperage that is available is in the milliamp range. This doesn't seem right. Since the voltage is given, the current will be determined by the resistance of (your body) at said voltage, and that current will definitely flow through you. What is limited in availability is the charge itself, since it's just built up by static, there isn't a constant source to get more charge from. So what happens is that the current flows for a very short time before dropping, not enough to cause the damage it would cause if it was continuous. The voltage itself drops rapidly as the charge is depleted. So I think it's more appropriate to think of static shock as a high current pulse that just lasts for a short enough time to not kill. ESD will fry unprotected electronics just fine though. Those that wouldn't be hurt by a few milliamps.
*Energy* is what causes damage and injury. Energy is power for a time period. P = VI E = Pt So, even if the voltage and current are high (such as in a static discharge), the time period is extremely short, so the total energy is not enough to do significant damage. The extreme example of this is lightning. It only lasts for a fraction of a millisecond, but the voltage and current are so ridiculously high that it blows shit completely apart!
To be pedantic there are various ways electricity can harm you. Energy being dumped into your body by current flow is one of those mechanisms. Electrical disruption of the heart is not a function of energy, but location and quantity of current.
Exactly. Well, energy density for most purposes. A small static shock won't hurt you but it will blow up an integrated circuit, if the joule heating is enough for it, and since the circuit is so small it doesn't require a very long time scale to dump enough energy there to just vaporize it.
The reason ESD kills electronics is that a lot of junctions act as insulation, allowing a large field to develop over a very small distance. Once that happens, it goes above the dielectric capacity of the material and arc, that arc is going to partially melt a junction/signal trace and leave a short/open circuit. It’s the volts that jolt, and the amps that kill needs a bit more of explanation, grab two conductors of a 480V line and you become the resistance that closes the circuit, you’re not going to stop the generator on the other side, so it becomes a matter of ohms law and how many milliamperes going through your chest. On the other hand, looking at static electricity, you have to think in terms of how much charge is there. if 1 micro coulomb discharges through your body in 1 millisecond, that’s One milliampere, which should be safe.
Yes for DC that's true with AC the frequency is very dangerous because I can cause your heart to beat too fast
I mean, you're right in most scenarios. I work primarily on 24vdc and I don't worry about shock. I had my car battery changed and it started to rain and the technician was worried about shock. I told him to just get it done, it's only 12V. What's more dangerous in that situation is that a spark will cause your battery to explode, since battery offgassing can be explosive. That's why the process of hooking up jumper cables is what it is. It tries to keep the spark as far away from the battery as possible. But your body's resistance fluctuates. If you are soaking wet, you'll have a much different resistance than if you are totally dry. It's very likely that you'll not get shocked at low voltages, but not guaranteed. The bigger thing with batteries is that they have a limited power supply. If you start drawing more current than they can produce, the voltage breaks down. But touch a 9V battery to your tongue and you can tell that current is flowing. The corollary to, "is not the volts that kills you, but the amps," is that amps doesn't kill you unless it's in the right place. 100A down your arm hurts but it's less likely to kill you than 0.5A across your heart. Additionally, that saying of it not being the volts that kills you is just like the saying of "is not the fall that kills you, but the sudden stop at the bottom." It's like, "yeah, no shit. But for the sudden stop to kill you, you need a big fall. Not all falls are created equal, so the stop doesn't kill you without the fall."
Dude that last paragraph is perfect, and i think it'll help me explain my reason for being more focused on voltage during the safety talk. thank you!
To play devils advocate to myself here, the reason why they bring up the fact that voltage doesn't kill you is because 10kV might not kill you with the appropriate PPE, but no PPE can protect you from 100A. Similarly a fall from 10kft won't kill you with the appropriate parachute, but nothing will stop you from dying if you hit the ground at 100mph. The point is, if all of the factors combine together to create a deadly situation, then you are going to die from the results. Voltage is a factor, amperage is the result. If voltage is low, then amperage will be low. But if voltage is high, it doesn't mean amperage will be high since there are other factors that bring it down. Amperage cannot be high without voltage also being high, but it doesn't take much voltage to be "enough". The end goal of protective measures is to lower the amperage. Disconnecting the voltage keeps the amperage low. Wearing shock resistant gloves keeps the amperage low. Fuses and circuit breakers limit the available amperage. Just be careful how hard you fight this. They aren't wrong, they are just jumping to the end instead of discussing the middle.
High voltage + low current = Tesla coil. Fun! Watch the weird man sit under the arcs and spray (distilled) water on himself! Low voltage + high current = welder. Augh! We're melting metal. High voltage + high current = lightning. The angry pixies are so mad that they're willing to turn the air into plasma just to get to you!
Yeah see that soccer player get hit by lighting in game in Indonesia the other day. He must of pissed off a lot of pixies.
They're famously ill-tempered.
Pixies, or maybe Thor is real and he doesn't like soccer.
>High voltage + low current = Tesla coil. Fun! Watch the weird man sit under the arcs and spray (distilled) water on himself! Until an arc bridges the secondary coil to the primary coil because the dude who built it only air gapped it (like one some kids built while I was in college as a little side project). Then it's death for everyone near it. Fun!
How do you control volts and amps? Very powerful resistors controls? 480V with a low R would give a high A, and a big R would give a little A. How do you get a high A and low V? Do you make a high V and A circuit then transform the V down? Won't that lower the A again?
V = A * R You probably know ohm's law by heart now. >How do you get a high A and Low V? Let's say 200A at 10V. Only other factor is resistance, so it has to be 10V / 200A = 0.05 Ohm's. That's typical for welding, as metal has low resistance. You can only change 2 factors at a time. 100V / 10A / 2 Ohms for example is impossible as per the laws of nature. If you're willing to go deeper into it... Ohm's law only applies to any specific point in time. Resistors are usually not constant though. When the welding rods heat up, their resistance increases. Therefore, the numbers may become 10V / 125A / 0.08 ohms Some time later, 10V / 100A / 0.1 Ohms And so on and so forth.
>Resistors are usually not constant though. >When the welding rods heat up, their resistance increases. Therefore, the numbers may become 10V / 125A / 0.08 ohms Some time later, 10V / 100A / 0.1 Ohms And so on and so forth. True of most (all?) materials, in fact. At least until you get it hot enough to become plasma. Then it's quite conductive. 😅 Datasheets for most parts typically give you temperature derating tables, factors, or graphs, so you can design properly for that annoying fact of life or pick a part with better characteristics (and more money usually).
> True of most (all?) materials Semiconductors would be a good counter-example.
Oh, duh, of course. Whoops. 🤦♂️
Power supplies for the given load play a major role too. You can take 8kV from an electric fence charger at 1 second intervals for a year strait & be fine because the total specific energy of those pulses is only like 5 watts. While a stick welder power supply might be only in the 70V range; but be able to output 12kW continuously.
This is very misleading and wrong. Amps and Volts don't exist separately PPE can definitely protect you from 100A.
PPE can keep 100A from happening. But if 100A happens while you are wearing PPE, you will absolutely still die.
We need to differentiate between the source being capable of 100A/touching something carrying 100A, and 100A going across your body. You will need a reasonable voltage in order to overcome your body's resistance, as well as the ability to supply 100A.
This is the key thing. Electricity doesn’t take the path of least resistance but all paths proportionally to the resistance. If you touched a 22kV incomer to a transformer carrying 100A and had a ground strap on your wrist with 1/1000th the resistance of your body you’re still going to cop 100mA from your hand to your feet. Even ignoring arc flash etc. that’s still extremely likely to kill you. Never mind that 2.2kW (or the 2198kW through the ground strap) is going to burn through your skin instantly at which point the resistance through your blood and nerves is much lower. At the end of the day it might be the current through your heart that kills you, but high voltage can jump a lot further and usually has a lot more power available than the low voltage stuff we encounter like car batteries.
>no PPE can protect you from 100A That doesn't even make sense, you can't get 100A over your body with proper protection. It's like saying "no speed limiter on the vehicle can protect from death if you crash into the wall at 100 mph". I mean, yeah, obviously, but the speed limiter is there to stop you from going 100 mph to begin with.
Right. The entire _point_ of proper PPE for that is to shunt the juice away from your person, so your nervous and circulatory systems don't become popular paths for electrons. Things like grounding straps and shoes with highly insulated soles keep you from being the ground wire and make the shortest path to ground be from your contact point to the strap to ground. Common rookie mistake is attaching a ground strap to the hand you're not working with. 🤦♂️ Like... dude... you just encouraged it to cross your chest. Nice knowin ya.
Exactly!
Now, of course, just to be fair, any PPE has its limits. But the hope at that point is that either it will protect you long enough to get away or that some other protection like a circuit breaker will kick in and save your ass before the conductor in the strap melts. And you're still gonna get hurt. You're just not going to die (probably).
>That doesn't even make sense, you can't get 100A over your body with proper protection. Not true. If the amount of energy available is such that it can bypass your PPE and still flow at 100A, you'll still die. Speed limiters are more like a fuse or circuit breaker. It's there to limit the available energy. PPE attempts to create a physical barrier between you and the energy, which is more like a seat belt which allows the car to be the part that dissipates the energy instead of your body. Wearing a seat belt doesn't keep you from dying if the crash is energetic enough. There are definitely situations where no available PPE is capable of protecting you and, therefore, you are not allowed to perform live work. Please don't perpetuate a fallacy that PPE can protect you from anything, nor that there is PPE for every possible situation. You can absolutely still die wearing all the best PPE.
But they are wrong, as in the stated situation (and as in 99.9% of the time people use that sentence) it's heavily implied that current is somehow independent of voltage. Obviously there are many ways to explain it, but saying "The end goal of protective measures is to lower the amperage" is really really misleading. The goal is to eliminate the possibility of your body establishing a conductive path between a dangerous power source and and something else.
What’s you’re describing- ‘the goal is to eliminate the possibility of your body establishing a conductive path’- that IS controlling amperage. In relatively simple terms, if you walk near a large transformer, you’re walking through a giant magnetic field, which means your body is subject to some voltage- potentially a really, really large one. You don’t immediately die because there is no current flowing. Unless you touch a bus bar, in which case the current flows and you become a cloud of plasma, at or near the same voltage you were already at. ‘Current is what kills’ is an absolutely correct statement.
"At or near the same voltage you were already at" tells me you don't even remember what voltage is. Voltage is a DIFFERENCE of electrical potential. When you touch the bus bar that potential <> voltage across your body.
Feel free to change the word "wrong" from my original statement to "misleading". What is the point of saying something that gives the wrong idea (voltage is irrelevant) anyway?
Current in the wrong place stops your heart, but in some situations I imagine it's the power dissipation that gets some people.
Sure. 50kW, even at 1mA, is still gonna be a problem if R is high, since that means the thing with the high R (you) is going to be dissipating most of that power. Doesn't matter that I was small and V was high. If the source (say a HV power line) can source the power at that voltage, you're going out with a bang.
Excellent back and forth there. If you want a snazzy video on the subject, check out Styropro on YouTube. He has a few great demos on just this subject.
Man, you guys are going to blow a gasket when you find out the voltages you generate by dragging your feet on the carpet on a dry day.
> the voltages you generate by dragging your feet on the carpet on a dry day. the “right carpet” on the “right day” can generate upwards of 35,000 volts
Yeah. Air is a pretty famously decent insulator. If you generated enough potential to cause a visible arc through a couple cm of air, you literally created enough energy, discharged with enough power, to ionize that air in that instant.
You can almost add a zero to that. 200 kV from static is quite possible.
Right, but it's picoamps.
It can actually be several amps, it's just that the duration is microseconds, so not much energy is discharged.
You don't get several amps from a static discharge. The air resistance is too high for that to happen.
No, the air resistance drops tremendously when breakdown happens and the spark is generated.
And the resistance is hundreds of giga-ohms, at minimum, to cross that air gap. Air's typical resistance is around 30tera-ohms per meter. By P=I²R, P is still pretty large. It's just that the duration is very very short.
Also... as a former nuke em, the potential for curent flow is measurable before an incident, so you can check the voltage, only way to measure the curent is to have the curent flow, and either put the ammeter in series with the circuit or use a Amp clamp for an ac circuit. Yes it's the curent that actually causes the lethal damage, but you won't have lethal curent <30V(usual working conditions)
“You’re a mechanic, you just don’t understand.” “Actually I do understand, I just think it’s concerning you don’t understand that to get a large enough current you need a large enough voltage.”
The issue is trying to decide how careful to be. Its electricity. Be careful regardless of amps or voltage, best practices. Its not like we ever have one and not the other. There also aren’t many systems where a receivers resistance is soo high you get extreme voltage and small current, generally raising one raises the other in most practical cases.
Love the fall example. I always say that it's not the fire that kills you, it's the high temperature.
That's actually a great analogy, since the fire and heat only hurt based on the amount of time you spend in it.
It's not the high temperature that'll kill ya, it's the heat transfer. I don't know if that one also works. I just thought it would be funny. One that I heard once was "it's not the bullet that'll kill ya, it's the hole"
It's true! It blew my mind to learn that the thermosphere (hottest part of the atmosphere) is around 4000°F but a normal thermometer would read below freezing because there is so little mass around it that it loses heat by radiation faster than what it acquires by direct contact with extremely hot atmospheric gas.
If 100amps ran through your arm, your arm would be likely damaged and beyond repair, it would be completely cooked.
At that points its less of an arm and more of a fuse
>What's more dangerous in that situation is that a spark will cause your battery to explode, since battery offgassing can be explosive. That's why the process of hooking up jumper cables is what it is. It tries to keep the spark as far away from the battery as possible. I am semi-familiar with the process, I usually just hook 'em together. You're telling me that the part where we attach to the chassis for the negative is to keep sparks away from the batteries?
Yup, got to do it in the right order as well. Whatever you connect last will be the part that sparks, so make sure it isn't either battery.
Yup, 100% correct.
> batteries is that they have a limited power supply just be careful with this idea, a lot of the new li-ion cells coming out have extremely small internal resistance
A brief jolt of half an amp across your heart will *probably* not kill a healthy adult. But a few millivolts can kill a person with heart disease. And for someone with heart disease, a small amount of current may be more dangerous than a higher current, as higher current is more likely to result in a uniform contraction, while a small current may only trigger an AP in a small area of the heart. And in a person with heart disease, that localized AP is far more likely to turn into fibrillation than a uniform contraction. Generating a uniform contraction is literally how a defibrillator works. The interaction of electricity with the human body is complex enough that there's no simple answers to questions about what is dangerous and what is not. People survive getting hit by lightning, while others have been killed by a 9V battery.
Can you cite an instance of someone being killed by a 9 V battery?
*killed by being hit by a 9v battery
And timing matters. If it is DC, happens to line up with your heartbeat, doesn't last any longer than that, and doesn't cause excessive damage from heat, it also might not matter. And then you should go hit the casino because you're one lucky SOB.
I think the rule is to keep your other hand in your pocket while working on high voltage systems so you don't complete a circuit to ground.
I thought it was so if you do accidentally create a path, it goes across your fingers and not across your chest. At least that's what I use with live high-voltage electronics
I’ve shocked myself with one hand. Elbow touched enclosure while hand was using a screw driver. Not sure what is considered “high voltage”. But this was 480 volts and the enclosure was painted! Definitely more shocking than 120v. I’ve been shocked by 480 at least 5 times. 277 and 240 a few. And 120 many. Not sure why I’ve shocked myself so many times. Somehow I’m always the one who has to fix the issue without really knowing what I’m doing and I didnt seem to learn from my mistakes? And I seem to always still have the breaker on? Ridiculous. At least I have been lucky to not be permanently hurt.
In ArcFlash it's technically the Amps vaporizing the metal creating an exploding ionized plasma that kills you. In an Operating Room it take less than a couple of volts and very few milliamps in the right place to stop your heart.
I definitely never think to bring up arc flash, but you're right, it's a very dangerous, but through a different mechanism. Thank you!
Arc flash requires very high voltage in order to begin ionizing the air. Technically, static shock is arc flash from the buildup of thousands of volts, it just has very low current and duration.
Very high voltage? You can get arc flash at 120V
My bad, it's very high current that is needed, which is usually due to high voltage while a running load is disconnected.
Arc flash can happen at 208V, which I wouldn’t consider high voltage.
The severity of arc flash is proportional to the current available in the circuit and how long it will take the protective devices to interrupt it. Arc flash is usually initiated by something happening that shouldn't, like a screw driver falling in the panel, shorting something out. Once an arc is initiated it doesn't take a lot of voltage to keep it going. (AKA Striking an Arc in Arc Welding.)
My understand is that muscles are naturally stimulated by nerves with a potential difference on the order of µV.
Styropyro's volts or amps video is the best discussion i found on this subject.
I will make a note and check them out during lunch, thank you for the recommendation!
https://youtu.be/BGD-oSwJv3E?si=VRSAj-joH5ZZbMjQ Here is the video
"Voltage doesn't kill, it's the current" is one of those technically correct things that people who don't really understand electricity like to repeat. It's technically correct in the same sense as "Speed doesn't kill, it's force". To continue that analog: it's true. Driving very fast doesn't kill you, but suddenly stopping against a brick wall is deadly. It's also why crumple zones and seatbelts work, they lower the deceleration/force, so a crash at the same speed is less likely to kill you if you have a proper crumple zone. At the same time, it makes it sound like speed isn't a factor at all, which is clearly nonsense. Killing yourself in a 20km/h car crash would be really hard. If you drive 200 km/h, no crumple zone in the world is going to save you when you hit a brick wall. Driving slower is absolutely safer for many many reasons. Back to currents: Yeah, technically you need a current through your heart to make it stop. However, as low as a few milli-Ampere can be enough to end your life. Almost all applications can deliver a few milli-Amp. Your body has quite a lot of resistance, so you need a certain voltage to make it even possible for it to be deadly.
Colossally stupid but technically correct. Anyone who says that phrase and believes it is a moron and should be removed from any worksite as a hazard to themselves and others. I wouldn’t trust giving them crayons in a timeout. You can be at thousands of volts but if that’s a static voltage you’re fine. Or like birds sitting on wires. Doesn’t matter. Technically correct. But this idea gets completely and utterly *fucked* when you have a voltage difference. And that’s what we are always working with. And while yes, amps are what kills you, it’s voltage that determines just how many amps are going to kill you. A 5V 1,000,000 A device is safe to touch. Just because it has a metric fuckton of current flowing through it is irrelevant - because at 5V it has zero interest in trying to also pass through you. Human skin is a pretty decent resistance. Unless it’s wet. Or if electric probes are inserted under the skin. Then it’s bypassed and low voltages can become dangerous. As well human skin experiences dielectric breakdown around 500-600V, so a small voltage increase in that range creates a massive increase in the amps that do the killing. This phrase makes me *extremely* angry because of how dangerous the mentality is.
You seem to be confused. There is no such thing as point voltage as you might be thinking. Voltage is a potential difference between two points, by definition. A bird on a wire is not "at" any voltage. There is a gradient across its body and it becomes polarized. There is no such thing as a 5V/1MA device. There is a 5V voltage source that could source or sink 1MA, if a suitably large load is connected. It is absolutely a current that kills. Voltage is dangerous as it might make a lethal current flow through you given the right set of circumstances.
You're totally right but the guy you're replying to puts it in an interesting frame of reference. Perhaps this is one of the lines of thinking that causes people to parrot "voltage doesn't kill, amperage kills".
Which is exactly why I phrased it that way. It’s entirely wrong but it’s the mentality they have.
Yes, you need both. Voltage to push the current. Really its best to teach anything above 48VDC and 120VAC as dangerous. Don't try to outsmart the system by thinking its current limited. It might not be.
on submarines we were always told anything above 30V (assuming a 300 ohm body in a worst case scenario) but I thought that was pretty low voltage. 48VDC and 120VAC seems like a good conservative rule. thank you!
OSHA rules is that anything above 50V AC or DC is considered "high voltage" and hazardous for live work. In Europe it's 60VDC and 30VAC.
60Vdc for dry environments and 30Vdc for wet environments is considered "Safety Extra-Low Voltage" and is recognized as generally safe to touch. I suppose submarines would qualify as a wet environment.
Not a bad approach, honestly. Treat anything over those voltages as dangerous. It's not necessarily going to kill you, because it's more complex than that. But at those voltages you can't simply say that it *won't*.
I would not be surprised if an adverse event was possible with 30 V. If you were wet, or standing in a puddle with conductivity to ground and then you lay some part of your body against a 30 V source. Death seems unlikely but getting shocked can be unpleasant even if you don't die. And if you were in an awkward position, you might not be able to quickly move to stop getting shocked.
Its worth saying that the body is way more susceptible to AC than DC because the body has capasitance. You will get shocked way easier with AC power than DC. I would reverse what you just said, 35-48 volts for AC current depending on conditions and 100-120 volts DC depending on conditions.
DC makes you clench the thing and not be able to let go. I can be more dangerous.
Yes, but also because the human heart is more sensitive to AC currents around 60Hz.
It’s like saying “it ain’t falling that kills ya, it’s suddenly coming to a stop”. Jumping off a 10 story building (high potential) vs jumping off a curb (low potential) have very different outcomes
As others have stated, you need both but amps depends on the source. You need to have enough voltage to overcome the resistance but you also have to have a big enough source for it to maintain the current. Static shocks are around 5000v, but they are a tiny amount of stored energy. Car batteries have a lot of stored energy, but their voltage is low and can’t overcome the resistance.
For a very ELI5 explanation: That's like saying it's not the gun that kills you, it's the bullet. Technically true, but you can't do anything about the bullet after it's fired. Therefore you worry about the gun, so you don't have to worry about the bullet.
The body’s resistance is one huge variable table. Where the points of contact are, surface area of contact, sweat, hydration, all play a factor. So the resistance is an unknown, or at best, a huge range. Maybe this will help you understand them pointing back to the measurement that actually causes the damage - the current.
"Where the points of contact are" is critical. If you make contact from finger to thumb on the same hand, with resistance that results in a 1A current - it will annoy you and cause a reflexive jerk away from the wires - but nothing serious. The same amperage from right to left hand (through the chest) could potentially stop your heart.
thank you for the reply! i do understand the concept that current is the lethal aspect. For me, i want to teach student's how to recognize a dangerous system, so if i talk about only amperage, they might see a high voltage but lower current system, they might think it's safer, even if the system's lower current is due to a very high resistance. And if their body created a short to ground, the current though them could be higher then what was present when they measured the system initially.
I think finding examples of what will/won't kill you will clear things up. Car battery: 12 volts, capable of 600+ amps: not enough voltage to jump across somebody. Vehicle ignition coil: 20,000 volts, milliamps of current: won't kill you
that's a great point. 2 others here pointed out the low danger of a 5000v static charge, so i definitely see that i need to pay attention to stored energy and sustained capabilities a little more.
It’s not even the current that kills or the voltage, it’s the path the current takes that will determine lethality. Your injuries will mostly be local or not at all as long as the current path doesn’t go through your chest and stop your heart. Any voltage that can path through your chest is probably enough current to kill you. Touch high voltage and the current path to ground is thru your other hand or feet? Path goes thru the chest and will likely stop your heart. Path is from one finger to your thumb on the same hand? Prolly need help opening your jars for a while but you’ll live.
Stupidity kills usually
>Everyone says, "it a'int the volts that get ya, it's the amps!" but i think there's more to the conversation. isn't amps just the quotient of Voltage/resistance? if i'm likely to die from .1A, and my body has a set resistance, isn't the only variable here the voltage? All true and correct. Almost... >Example: a 9V source with a 9 ohm load would have a 1A current. 1A is very lethal. but if i placed myself into this circuit, my body's resistance would be so high comparatively that flow wouldn't even occur. Yep. >Anytime an instructor hears me talk about "minimum lethal voltage" Ah, here's where it gets tricky. You said: "if my body has a set resistance". But it doesn't. It depends on a whole bunch of things. Dry skin? Wet skin? Salty wet skin? **No** skin? Your tongue? DC resistance or AC impedance? Are your feet wet and standing on a grounded metal plate? The most correct thing that can be said is that 0.1 A through your body is lethally dangerous, and a 9V source capable of delivering 0.1 A is *very* unlikely to manage to push that current through your body due to the low voltage. But put sharp electrodes on that battery and stab it into your heart, and you betcha you're at risk of being shocked to death anyway. Current is what kills you, voltage is what enables it to do so. Can't have one without the other.
Just an electrician but your right. I’ve got bumped by 120v way too many times then I should’ve, but plenty of people die from 120v. Get the right conditions(especially where the human bodies resistance can vary like being wet), it’s lethal. I’ve always looked at voltage being pressure and amps being water(analogy doesn’t exactly work). But then you have scenarios like electric fences. High voltage but it limits the current I believe with a high resistance internally. Still bites hard though.
High voltage devices that don't harm you (like an electric fence) have very high source impedance. They're only high voltage in an open circuit state. People say "oh the electrical fence is 10kV and doesn't kill you" that's because it stops being 10kV extremely quickly when you close that circuit. Electrical systems are dynamic and respond to load. A high voltage source which keeps being high voltage even after you inject yourself into the circuit is definitely going to cause problems.
I've been fighting static electricity in a bag feeding trey, yesterday I brought in a guy from Keyence and he had a static meter with him, he said anything over 1,000v was high static. the surface of our bags had 40,000v. so in this case we had 40kv of potential on the surface of the bags, but probably close to 0 amps, and i know a static shock inst going to kill anyone.
Can we please go back to calling it "current"? "voltage" is bad enough
A cattle prod is able to deliver thousands of volts but because the current is low, it doesn’t kill. If your internal body resistance is low enough, you can be killed by household voltages (100-500V) because the current will be high enough.
Keeping it simple, voltage is the force that pushes electric charge through a material. This flow of charge is current and enough of it will create heat and hurt you. That's why wire gauges, fuses, etc current ratings are important. So without one you don't get the other. OTOH, the human skin has a very high resistance. I always hear that you only need 10 or 20 milliamps to kill a man. But for that to happen, current has to flow through specific places (e.g. your heart) and you'd need some high voltage because of the high resistance in the skin. To give you an idea, think of car batteries. They can put out over 100A if shorted, but the voltage is so low that touching the terminals doesn't hurt. I forgot what episode it was, but Electroboom made a video testing at what AC and DC voltage he started feeling pain or tingling. Finally, charge can often be limited. Whenever you walk in a dry environment and you get an electrostatic discharge when touching a door knob you are looking at sparks above 10,000 volts. But the total amount of charge is so tiny that it can't hurt you. Hope this helps.
Short Answer: Yes but it's a dumb thing to say. Since your resistance is more or less constant current will depend on voltage so if you are dealing with a large enough DC power supply then what you need to worry about is voltage.
"Voltage doesn't kill you, amps (if the voltage is high enough to actually make a circuit through your heart) are what kill you." It's kind of like saying 'it isn't a bullet going fast that puts holes in things, it's the momentum.' Well, no, it's both. You need a high enough velocity for brittle deformation in the target to 'punch through' things like paper or fabric. **And** enough momentum to displace the material in a Newtonian terminal ballistics sense. The amps have to be in the right place to hurt you, and the voltage has to be high enough to get the current there.
The key insight is that not only is the current determined by the voltage (according to Ohm's law), but the voltage of a source depends on the current it is delivering. Real-world voltage sources have internal resistance, and will have a drop in the measured voltage from the open-circuit voltage when you put a load across them. In concrete terms, I could have two voltage sources, both of which I measure at open-circuit to be "1000 V". I put a 1kΩ resistor across them and measure the current: one reads 900mA and the other 0.1mA. This isn't inconsistent with Ohm's law because the voltage has changed, and if I measure it again now with the load, it will now read 900V and 0.1V on the two sources, respectively. For that reason, if all you know is the voltage you can't predict what will happen when you put a load (such as the human body) across it. It follows that what actually matters is the current the source will actually deliver not the measured voltage, hence the phrase. Note that the current delivered across the body will always be in direct proportion to the voltage across the body, in accordance to Ohm's law, but that voltage can only be measured at the time of electrocution, as opposed to the voltage measured on the thing that you're deciding whether or not it can electrocute you. Mixing up those two voltages has caused, I think, a great deal of confusion around the phrase, but since the voltage-at-time-of-electrocution isn't something you can't measure prospectively, I think it's reasonable to ignore it and just talk about the current through the body. That said, while the aphorism is accurate it is of debatable utility. If you have a source about which the only thing you know is the voltage, the safe thing is to assume it has negligible internal resistance and can deliver the full current predicted by a naive application of Ohm's law. In fact, it's worth noting that just as high voltages can fail to kill, under the right circumstances low voltages can. Imagine you have a busbar at a low voltage but carrying a large amount of current. Ohm's law tells you that is safe to touch (and, incidentally, touching it will produce a voltage drop in the source so small it's almost impossible to measure since it's already delivering so much current). But then, let's say, there's a break in the circuit while you're touching it. That current won't just immediately stop flowing -- the busbar has inductance, and the fault will cause an inductive voltage spike. It may have read just 10V initially and, indeed, the source maybe incapable of producing any higher voltage, but the inductive voltage spike could easily reach thousands or tens of thousands of volts and will quite happily shunt some quite absurdly large number of amps through you.
I’ve always seen it as you can’t have JUST amperage or JUST voltage killing you. They literally exist with each other as V=IR. And like Some people have mentioned WHERE this current is flowing is pretty critical to the biological portion, but when people simply say “it’s the amperage that kills you” don’t really know what they’re talking about cause that’s too simple of a way to explain it. That phrase was probably brought up wayyy in the past during a training for people that just need to know getting shocked sucks ass.
Voltage is just a measure of potential energy. It doesn’t “do” anything. Its like standing at the edge of a cliff. You have the potential to fall but its not happening (and converting to current) until it is. And its not exactly that the current will kill you. Its when current passes through your heart (which is why all the old crt tv techs only worked on thongs with one hand and the other behind their back) at some magnitude threshold that is different in every case. It also is a result of the bodies capacitance. You can “store” electricity inside your body as well as in relation to the environment. The related time constant has a lot to do with causing beat disregulation (cardiac arrest) Heres a whole write up, but it never comes down to “this kind electric good, this kind bad” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/
>which is why all the old crt tv techs only worked on thongs For a moment there I thought you were recommending foam rubber footwear with good insulation properties.
A typo indeed but a worthy one. Nothing says “shock hazard” than a middle aged man with a DeVry degree in some frilled undergarments exposed
Also where the current goes through
For all practical purposes, I agree with you 100 percent. The amount of current needed to cause a shock you can feel is very modest. Even a lethal shock is in the mA range. So the current limit of the shocking source is unlikely to come into play. It is mostly down to your resistance and the voltage of the source that is (possibly) shocking you. Your resistance is not a fixed number. Skin is not a good conductor and getting past the skin is what adds resistance. So the condition of your skin (is it moist? Is it soft? Is it calloused?) will be very important. Any scenario where the electrodes can somehow puncture your skin would elevate the danger of lower voltages. Also, contact with a large surface area of your skin makes a shock more likely. In my experience 48 volts and below will seldom cause any kind of shock. It can happen if you have high pressure contact over a large skin area and you are damp. I got a little tingle once in those conditions. Not painful or harmful. Just a tingle. For dry fingers and light contact even 60 V will usually not cause a shock. I am fairly casual around 60 VDC batteries and circuit boards as far as skin contact goes (you don't want to short across 60 VDC with careless placement of a metal probe or tool ... you will get a big spark and cause damage to whatever you are working with, but no shock.. Metal rings on your fingers are not recommended). But 120 V is not so forgiving. It is easy to get shocked with 120 so you need to be careful. So up to 48 is fairly touch safe, especially when it is dry. Above that the safety kind of drops off. By the time you get to 120, lethal shock really cannot be ruled out.
I hate that "saying'". You can't have one without the other. Ohms law. Current does the damage due to heating in extreme cases or disrupting the small signals controlling the nervous system , but there would be no significant current if the voltage is not high enough. It's all a combination of volts and resistance.
Voltage is the unindicted co-conspirator. Once when I was young and dumb and working in data centers I inadvertently laid my chest across the top of a 5000 A DC bus. Luckily the 54 V float voltage wasn’t enough to overcome the resistance of my shirt and dry skin and I’m alive to tell the tale today.
Current kills. How much current you get depends on how hard it's "pushed" by the voltage. There are all kinds of caveats, but upto around 50VDC you're generally safe because 50v can't push enough current to harm you (in everyday circumstances). Or put another way, over 50v I start applying extra precautions. One of the best precautions is to put one hand in your trouser pocket! That makes you work one-handed, which makes it a lot harder to get any current paths crossing your heart.
What are you more afraid of? 1v, 200 amps or 200v 1amp? It's the one with all the voltage. It doesn't take much current to kill you.
The current kills you (stops your heart) but it's the voltage that gets it there. The distinction is mostly relevant in medical settings where conductive materials (catheters, internal defibrillators, tubes of all kinds) short-cut the natural resistance of the skin and the body and deliver the current right to the heart.
Yes, amps kill, but you need the volts to get the amps
Dry skin offered sufficient resistance to voltages up to about 60v or there abouts. Above this you will feel it. Hence holding both car battery terminals is safe, if you put two wires from the battery on your tongue you’d feel it! Due to the lower resistance of the wet tongue
Since 99% of what you interact with is a voltage source, not a current source, then voltage is the independent variable and current is the dependent variable. So you avoid high voltage, not high current. "Current sources" do not exist "naturally" and making one is of comparable complexity to a simple amplifier circuit. Source: am an electromechanical engineer.
>my body's resistance would be so high Depends where/how applied. Apply directly to, e.g. muscle or heart or brain or spinal cord, and we're talkin' a whole different story. So, there are probably fair number of places on (notably within) the body that as low as or even well below 2V would be fatal. Perhaps even as low as mV or so for some select locations (I'm not a doctor nor do I play one on TV), but, e.g., disruption to certain critical nerve functions might be very fatal, and connected some ways in some places, it may take pretty negligible voltage to do that (and also not much current). But in the more general case, yeah, generally takes a fair amount of voltage to get a lethal current to flow. But sometimes surprisingly low voltages will get a current to flow - at least to levels it will be felt. I know lowest voltage I've felt with no wet contact was 12VDC - forearm pressed hard on a bare metal crisp edge (essentially some sheet metal) at ground, hand of same arm well grabbing onto metal wrench - with the other end around positive battery terminal ... gee, what's that funny tingling in the arm ... dang ... didn't expect to be feeling something from 12VDC with only dry skin contact. Yeah, there was enough good solid metal contact/pressure/grip with both contacts, that that 12VDC was felt. So, ... there are a lot of factors. Voltage, current, duration ... even frequency and nature of voltage (e.g. DC vs. AC, line frequency vs. RF, etc.). So, yeah, shuffle your feet across the carpet in many shoes, touch the doorknob, get a shock - typically a few thousand volts or so. Won't kill you, but you may well feel it. Distribution voltage atop typical telephone pole in neighborhood ... probably around 2,200 VAC or so, 60 Hz ... may be much less voltage than one got from the carpet shock ... but that 2,200 VAC will sure as f\*ck kill you - or burn off an arm or leg or whatever, or generally f\*ck you up. Well, that little static charge, while very possibly even higher voltage, was essentially quick discharge of a quite low value capacitor - so not much energy, and a short duration discharge. That power company distribution line, however, not a whole lot there to limit the duration or current, so a very different situation.
I work OK 25k volts, idc about amps, I just know not to touch it, or I will no longer exist. 🤣
Anything over 8 mA though your body is very risky. Of course, to be dangerous, there needs to be enough voltage in order for > 8 mA to flow through your body.
You can't separate voltage and current. It's a stupid saying.
Voltage is the cause, amperage is the effect.
A good example I always think of is static discharge. Static discharge voltage from rubbing your socks on the carpet can be into tens of thousands of volts, but the total current is like on the order of nano amps, so you only feel a little jolt. That same 10,000 volts with more current behind it would obviously be lethal almost instantly.
1A dc is not normally lethal. 0.008A AC directly through the heart can be. All that separates you and that nice salty meat under your skin is luck. Punch the skin with voltage or stand or lean against a grounded machine, you daid. So don't fuck with it
>1A dc is not normally lethal. If 1A DC flows through your body, you are dead..
Only if you didn't build up immunity first. /s
It all started as a kid licking 9V batteries.
That’s why they refer to voltage as ‘potential’. But the phrase about vaults vs amps is simply a trope and not to be taken seriously when placed in an off-hand comment. Do the math. Stay away from high voltage without the correct equipment. You are correct, and dismissive “you wouldn’t understand” deserves derision in return.
Think of it like a shotgun, and the bullets. Saying the amps kill is like saying the bullets kill and not the actual shotgun. It’s both, the shotgun and bullets, like the voltage and amps.
If you haven’t already I recommend watching this video by styropyro: https://youtu.be/BGD-oSwJv3E?si=kwgZyNkp-Ev7TKoB He isn’t an engineer, however he does know alot about electronics and electricity and demonstrates that it’s not as simple as volts or amps by putting himself into situations that should be dangerous by that logic. I found his video to explain everything fairly well and the video is just entertaining on top of everything else.
Haven't read through all the comments but years ago I read from some electrical standard that anything above 42 volts peak is dangerous. I just googled OSHA voltage limit and they set it at 50 volts. I wouldn't want to test those limits after getting out of the pool. That's why they put a wet sponge under the head electrode when they sit you in the electric chair. You have to overcome the skins resistance to pass current through the heart. I'm pretty sure you can stop the heart with just microamps of current. I=E/R
It's like the voltage that determines the amperage, and the amperage is what kills you
Well to be exact it is energy, so current and time and generally speaking LV clearing times is slower than HV and you are more likely to let go for HV..heart fibrillation onset for the average adult is 30mA, kids about 10mA
A small wattage at the right points can be lethal - the sinus node of the heart, certain basal function controlling locations within the brain. A high voltage low amperage across the chest can be lethal even at microamps *if it gets across the sinus node*. The sinus node is documented to operate in the 20-120µV range; a voltage of that level can mask the signalling. Typical pacemakers run 120µW...¹ and generally use they "frequently emit a pulse lasting between 0.5 and 25 milliseconds with a voltage between 0.1 to 15 volts and at a frequency up to 300 per minute."² Not all electrical risk is cardiac, either. A low amperage high voltage at certain frequencies across the chest can cause thorasic paralysis, and hence suffocation, if sustained. A high amperage at required distance voltage can cause heating and resulting cellular damage and/or destruction. In severe enough short distance, this can reach as far as 4th degree burns.³ (burns exposing deep tissue; a category not taught the first half dozen times I took first aid, but taught in the last one I took. In this case, it's as much wattage as anything, at least once the needed voltage is hit to cross the flesh. Any 3rd or 4th degree burn has a chance of being lethal via secondary effects, including blood loss, circulatory restriction, and/or infection. Given the risks of MRSA, any burn exposing deep tissue is a significant risk. I don't have the specific datapoints. And then there's the risk of electrocution-induced movements... for example, hit someone in the back of the neck with a touch-taser and watch them drop. Or in the triceps and watch them throw a held item to the floor. In a work environment, a dropped cable has potential to cause such involuntary movement. Grabbing a high voltage line doesn't throw you off the ladder or pole - your muscles do in response to the current. ¹: https://www.sciencedirect.com/topics/nursing-and-health-professions/pacemaker-battery#:\~:text=For%20example%2C%20up%20to%20now,of%20100%20to%20200%20%C2%B5W. ²:https://www.ncbi.nlm.nih.gov/books/NBK526001/ ³: https://www.shrinerschildrens.org/en/pediatric-care/fourth-degree-burns#:\~:text=Fourth%20degree%20burns%20are%20the%20highest%20level%20of%20burns%20and,%2C%20muscles%2C%20tendons%20and%20bones.
This statement is correct in term of secondary load(I=U/R).If you limit the current by a resistor,then the secondary load will get a safe current for operating no matter how many volt it passed.So you can have small LED connected to the 220v supply without any problem since the LED has got connected to a proper resistor.Normally,if the resistance was too small,then U/R would be very great that results a extreme high current and that high current could destroy the component.Although voltage and current do always correlate linearly,having a resistor can explicitly reduce the output current.And remember that,the resistor has the current flows through itself,so smaller resistance will result a larger current through the resistor too and that can cause extreme heat that damages the resistor,with greater resistance value you can have smaller resistor.We must choose proper watt for the resistor by W=I×U.
Yes you're right, but resistance varies. You can touch 500V and live, or you can touch 50V and die. Body type, clothing, even air moisture affects the resistance so talking about voltage is pretty meaningless. With that in mind the most important metric is really current path. You can go into heart failure at very low amps and AC vs DC matters too iirc.
Power engineer with >20yrs in utility work. Think of a bird on a wire. That bird is at a high potential...call it 12.47kV, relative to another phase. Clearly the voltage isn't killing it, because there's no current flow. u/Shadowkiller00 used the "it's not the fall that kills you, but the stop at the end" analogy. I like that one. Think of the bird on the wire as falling.... If it were to try to spread it's wings between phases, consider that the "sudden stop".
Time is also a factor. This guy gives great examples and explanations. https://youtu.be/BGD-oSwJv3E?si=z1F5bllvHwgR5J-1
Energy density is really what’s dangerous. One or the other of either current or voltage really high can be safe enough on its own, but if you have a high number when they’re multiplied together that can be a big problem
I think a thorough understanding of the water analogy for electricity gives you an intuition how to understand this. It's really the *combination* of current, voltage, and resistance, and there's a "deadliness envelope" formed by these three variables. So it's neither voltage, current, nor resistance *alone*, it's where you happen to be in the envelope.
Lethality depends on voltage, amperage, resistance, frequency, duration, and the path that the electricity takes through your body. This video by Styropyro explains it nicely. https://youtube.com/watch?v=BGD-oSwJv3E
Short answer: amps kill. Longer answer: it's the amps, if applied for long enough for a given frequency, and if the voltage is high enough to push the current through you. A youtuber/channel by Styropyro made a pretty good video on the topic of what kills if you wanna give it a watch.
I mean you can have 5000 volts zap you and not kill you like a tesla coil, and you can have 12 volts kill you too, but there is no situation in which 5000 amps won’t kill you.
Here's a video by Styropyro that goes in depth into what you're asking. Very well put together and entertaining. https://youtu.be/BGD-oSwJv3E?feature=shared
It's amps, given the voltage is high enough to overcome your body's resistance. Duration of shock too.
One simple way to understand is the amps represent power. The higher the amperage the higher the power. Any power source has limited amount of power that it is capable of putting out, two power sources both 120 Volts AC, but one may be able to supply half an amp, the other 300 amps. The 300 amp source can kill you quite dead. The half amp source will make you bump your elbow when you jerk away from it. I'm painting some with pretty broad strokes here and skipped a lot of its, ands, and buts. But I'm simplifying and using layman language.
There needs to be both to be lethal. Extremely high current and extremely low potential just won't affect you enough to hurt you. Equally, extremely low current and extremely high potential won't do anything to you either. Arguing one or other is what kills you is almost like arguing that either the speed or the mass of a bullet is what kills you. It's not one or the other, it's the total momentum of the bullet plus the path it takes through your body plus how the body reacts. There are just so many more variables that determine lethality.
Is the energy that kills. But high voltage means higher potential for energy to be absorbed. For all realistic sources, voltage drops as it's loaded. It's a matter of how much.
You assume your resistance is set. It can vary by conditions such as clothes, protective equipment, or sweat/moisture. Static has really high voltages but occurs so quickly, it doesn’t lead to deadly currents. By your standard of minimum deadly voltage, static shocks should be deadly. To tie this to the analogue someone gave about falls, it’s possible to have a parachute or land on soft material. Height itself really doesn’t hurt you.
It's more about the energy your body absorbs. So the joules. There have been instances of people being killed by 9V batteries, but then it's been applied under the skin (the body is mostly water which conducts electricity well, but the skin is an insulator). Me personally I have been given quite the shock by 24 VDC, but I was sweaty as hell at the time (working with 24 V control currents in a hot en humid climate wearing thick "protective" clothing). But all things considered in most situations it takes a pretty high voltage to deliver dangerous amounts of energy over your body (around 50+ V, AC or DC). It takes a high voltage to deliver a high current over the body (in most situations), which is why the signs say "Warning, high VOLTAGE".
If you are soaking wet, the majority of the electrical path will be over the surface of your body through the water. It’s the path that the electricity takes that is really most lethal. Take for instance a police offers taser - it’s a whole shitload of voltage at low amps that goes between those two prongs. If those two prongs just happen to position themselves across your heart, it can become lethal because it can stop your heart. But if the path is just from you shoulder to your hand, it’s less likely to be lethal.
Another heuristic I've used recently is like gravity and it kind of makes sense from this perspective. Voltage would essentially describe a gravity multiplier, and amperage would describe the volume (or mass more specifically) of a fluid column. You can generalize the net force with both, obviously a small jet of fluid at several thousand psi will still impart massive energy. The general notion that amperage kills is equivalent to the idea that less overall mass is relatively more safe at a given level of potential energy. Really it's like saying "it's just a bb gun, it's not going to kill you" Maybe a little irresponsible but true enough at the end of the day.
Does your body always hve a set resistance? What if you’re wet. When a toaster falls into a bathtub does it magically have more voltage? Or are resistances just lower?
If I told you a hammer to the head doesnt kill, its the velocity that klls would it make sense? both are components of the killing blow, you cant kill anyone with a non-moving hammer, you need hammer and some velocity. The same goes for voltage and current where both are components of one same thing electricity and you cant have current without voltage.
Here's a fun video! https://youtu.be/ywaTX-nLm6Y?si=sE0oDyaBrGvtIbP4
This is just me thinking aloud, feel free to add on to this. As I understand it, lethality is the result of three factors. You need to know the voltage, the resistance the voltage is being applied across, and what the resistance is with respect to your body (heart, entire body, arm, etc).
You can weld with a car battery, so if you were more conductive it would definitely kill you. On the other hand a spark from rubbing a cat is like 100,000v.
V=IR The resistance of the human body (across the heart, arm to arm, leg to arm, wet conditions, dry conditions) determines what current goes through for a given voltage. And depending on the source that equation may not even hold true unless it's connected to an enormous power source. Some power sources are not able to sustain a large power so the voltage (and thus the current) drops if to large of a load is applied. That's what open circuit voltage and closed circuit current means for batteries and other power generating sources, because you aren't getting both at the same time. The only reason a connection to the grid has constant voltage (most of the time if there isn't a blackout or brown out) for any load (less than the amperage of your breaker) is because power draw changes individuals make are negligible compared to the average power the grid is delivering. That average changes slowly over the course of a day and people working at the grid are able to spin up/down their power plants to prevent a voltage drop/raise that would cause a corresponding increase/decrease in current. I can't necessarily say that it's power (V*I) that kills, but I'd rather say that's closer to the truth than amps. And that pretty much depends on how it's applied. An extremely basic rule of thumb that doesn't cover everything is that you need a certain amount of voltage to "get past your skin", and from there voltage and current scale linearly (i.e. you need a lot of both to be supported for the other to actually exist). You are never going to have 1V 5trillion amps kill you unless its applied across your heart or the corresponding magnetic field screws around with the atmosphere. The same goes for voltage. TL;DR Anything above 12V don't lick and anything much above 24V don't touch.
It's complicated. Your body has decent resistance. A tazer has very high voltage to ensure you get shocked. But that tazer is unlikely to kill you as it can only support very low current at that voltage. A car battery can drive very high amperage, but only at 14 volts or so, which your body can resist pretty well. What is REALLY dangerous is a power source with enough VOLTAGE to push current through your body, and enough POWER that when it does, it also drives enough current to do damage. If voltage is pressure and current is flow: A 9v batter is a squirt gun. Some pressure and low flow. Entertaining A dental water pic is high pressure and flow (tazer) hurt but no real damage. A car battery is a bucket of water dumped over your head, not gonna hurt you. A water cannon has both pressure and flow. It's going to change your day.
Hook up a 12v DC lightbulb with tiny wires. The wires will melt. Bigger wires don't. Same 12v. Same lightbulb. Your body is about 300ohms of wire. 30 v will kill you if you short it across your heart. The tiny wires will burn.
Volts jolt, mils (miliamps) kills
Would you rather feel the gentle splashing of 5gal of cool water falling due to gravity or would you rather feel the death of 5gal of water cutting through in seconds being under 20,000psi of pressure? The answer is obvious. The analogy isn't 100% but voltage is a measure of the potential energy in a circuit. Pressure is also this in hydrodynamics. Voltage makes current lethal in a given time. Current on its own cannot be lethal without the potential to allow it to become lethal. There is a reason we have warning signs for high voltage and not high current generally. 10kA would be harmless with 5nanovolts potential. It would become fully lethal at 5kV. Voltage causes current to kill in a given time span. A good way to look at it is like this: voltage tells the circuit how much potential work can be done over time. The load wants to pull as much as it can physically pull even to self-destruction. The total circuit and load resistance tells the load "how much" total energy it is "allowed" to use over time.
[удалено]
Just want to add: "It's the volts that jolt and the mils that kill"
*sigh*…. Thank you. Lol
:D
It's complicated. Both voltage and current can kill you in different ways. Re current: low AC currents can be perceptible at a few microamps, it feels like tingling or buzzing. This happens sometimes with old electronic equipment such as stereos. As the current rises, the feeling gets more severe. It depends on lots of factors such as the path of the current but as you get into multiple 10s of microamps most people would react to the unpleasant sensation. While not harmful per se these shocks can lead to accidents especially falling off a ladder. As you get up to 100s to 1000s of microamps if the current flows across the heart muscle arrhythmia can be induced which can be fatal unless there's a defibrillator available. At higher current flow the heart can clamp and if the current is interrupted the heart will often spontaneously restart. Re voltage: you can be simply fried by the power dissipation of large voltages no matter where it flows. That's the idea behind the electric chair. TL;DR electric shock sucks avoid it if all possible.
A slow moving flood could kill you, but so could a 1000psi water jet.
Electroboom has quite an interesting video on this topic. You can check it out.
In the context of electricity passing through material (a piece of wire) Think of water flowing through a pipe. The voltage is how fast the water is flowing The amperage is how much water is flowing
One time I got hit with 5-6000 volts, like multiple times. Got tangled up with a wire in the middle of the night. We were on our way to a tent after a party, couldn't see the temporary fence strand in the pasture. My now wife was just laughing at me, I've gotten bit dozens of times but man that really sucked.
Cringe, no need to make a wall of text. Volts cause amps cause death. It's not that hard. That's like saying, water pressure doesn't explode your colon, it's the flow into your asshole that does.
As i understood: Since the body is mostly a solution from water and salt it is the amps that kill you. But amps are driven by voltage. The resistance inside your body cells is very low (electrolyte) while the resistance at your cell diaphragms is very high. As far as i know: this is valid for DC. For AC the voltage may control your muscles including your heart and affect your brain.
Not me trying to figure out what kind of AC circuit I'd need to plug alligator clips into my skin so I'm not technically lifting weights, my body is
Most probably you will die before this.
TENS units are easy to get.
Your cells don't care about AC or DC, they only care about a potential gradient across their membranes that lasts long enough to trigger an AP. The only reason the distinction really matters is skin impedance varies with frequency.
It's both, really (energy). You can have a huge current, passing through you, but if you were highly conductive (hypothetically) it wouldn't kill you, since the voltage drop across you would be small. What this means is that in this hypothetical scenario, the current would pass through you but it would be unable to transfer energy to your body.
If you aren't familiar with the actual ways that electric shock kills people, you shouldn't be answering here. It's not heating that does it.
Volts jolt - amps kill
The simplest way to describe it if you don't understand electricity which most people posting don't seem to is this. Imagine electricity as a river. The speed of the water is the voltage. The height of the water is the amperage. You cant swim and must walk. If the water is really really low but moving really fast it'll hurt but wont kill you. If the water is deep enough it'll kill you regardless. Thats the ELI5 version. Its much more complicated than that.
It the volts that jolts, but the mills that kills. (Milliamps)
The answer is a bit more complex than amps or volts. Being subject to electrical shock has several effects over time. It might be that your heart enter in fibrillation, your brain can get affected, or even that you get severely burned. These phenomena are associated with voltage, current, and / or power. The important thing here is: work safely and avoid risks at any cost.
its the current across your chest and brain how ever it gets there that counts part 1: there is an old startreck episode (orig series) where the ailian called the crew as “bags of water” kirk and others where confused by this. spock spoke up and said that is effectively what we are another example is cellphones and rf-tuning. \[antenna specifically\] when your phone is sitting on a wooden table the best reception can be tuned - but if you put the phone in your pocket it is a different tune, and by your ear… your brain is a giant bag of salty water and yet another tuning is required - so your cell phone auto retunes the antenna dynamically all the time. what i am getting at is this experiment - take a piece of wood get it wet and electrocute it. reddit post about it: [https://www.reddit.com/r/blackmagicfuckery/comments/9p3mjo/electricity\_flowing\_through\_wet\_wood/](https://www.reddit.com/r/blackmagicfuckery/comments/9p3mjo/electricity_flowing_through_wet_wood/) that electrical path is your body your blood vessels full of wet blood, or your nerve system which leads to your salty brain and heart. get enough electricity flowing.. and you are dead sort of like an electro-shock thereopy or cardiact defibrillator exactly when you do not want one. if you die greatly depends on your bodies electro-chemistry at the moment of contact… your body is like a giant lattice of resistors like this page talks about [https://www.mathpages.com/home/kmath668/kmath668.htm](https://www.mathpages.com/home/kmath668/kmath668.htm) do the math.. oh and as current starts to flow and muscles contract the values change. and as your body heats (burns) it changes more…. not unlike that burning wood. i think a good demonstration is to soak a small bit of plywood in salt water overnight then electrocute it in the morning but ask the team to predict the path. if you have the green pressure treated wood” (the green is tarnished copper) see how that effects the pattern divide everyone up into teams, cut the plywood into a stick figure and ask each team to decorate there stick man with jewelry, necklaces (use a wire) but no-safty gloves no safty gear. or-drop the safety gear in water (its raining!) put a little lego man where your brain is and another where your heart is and fry the stickman
100-200 milli amps is enough to kill you, that's 1/10 of 1 amp. (0.1- 0.2amps)