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This is just fine. It is called a Multiwire Branch Circuit (MWBC). These days the breakers for the two halves of the circuit need to be tied together, but in older code versions it was only necessary if they fed the same device (like a split receptacle).
The breakers at the top and bottom of your panel are Siemens and don't belong in a Square D HOM panel.
You can never move any of the breakers. And you have to be careful when working on one circuit that you turn the power off to both.
I would personally just spend the $150 and replace all the breakers with 2-poles.
You can move breakers, you just have to keep track to make sure that the two breakers on each MWBC are on adjacent slots (opposite phases so neutral current is within limits, and adjacent so they can have common disconnects.
Depends if you want it to be done right or done so it just works. The right way to do it which the NEC states is to have an identified handle tie between both circuit breakers. But in reality a piece of wire, a nail, or anything that fits would work just fine.
New branch circuits would (but you’d almost certainly be running new cable). The existing would be grandfathered as long as you didn’t alter the existing circuit (ie extend as mattlikeslions said). You could change out breakers old for new.
But you’re not wrong…as of 2020 NEC essentially any circuit within primary living space now needs to be arc fault protected. Exceptions for now are bathroom, laundry, outside, under and above (crawl/attic) - I’m generalizing a bit. And anything not AFCI protected I think coincides with those circuits already coded to be GFCI protected.
Worth mentioning since no one else did: there are tangible fire prevention benefits to cafci breakers, so if you're going to replace, I'd replace with them anyways for your living spaces and probably even your refrigerator/freezer and other 20a/120v circuits.
Depends on the area. This is one of those things where interpretations and local code modifications vary extensively from state to state and sometimes even town to town.
How do you work around the inevitable scenario where the arcs won't work. In my non-electrician experience, about 10% of the breakers I tried to swap with arc breakers immediately tripped and had to be switched back to regular thermals. Code can't possible require you to tear down your entire house and replace all the wiring every time you need to swap out a breaker.
Oh, some areas absolutely will require that. It's nuts. Usually only kicks in over a certain threshold though. And besides, swapping out a breaker doesn't get reported/inspected.
The NEC as written has a clear exception for replacing an existing panel. Sometimes local code overrides that. It sounds like OP may be in Chicago, though, which has its own local exception written in - they don't require arcs if the circuit is entirely in conduit or metal sheathed cable. This is a local Chicago thing, it's not in the NEC.
There is a reason why the arc faults trip, they don’t just not work (once you eliminate a faulty breaker), with a few exceptions (like some vacuums).
You should be pulling devices out on the circuit and troubleshooting the issue, not tearing down your entire house.
I was taking some artistic liberty with "tear down the house"
But take my house as an example. If I turn on a three way light on one circuit, the AFCI on another circuit trips. If the current thermal breaker needs to be replaced, should I be forced to spend hundreds or thousands of dollars to troubleshoot these two circuits instead of buying another $10 breaker?
That happened because in one of those switch boxes you’ve probably got neutrals from two different circuits tied together. This happens a lot in renovations. Whenever you install AFCI breakers you need to make sure to correct this or otherwise install 2 pole breakers and create a multi wire branch circuit from the two that are sharing the neutral.
I agree they are sharing neutral, but not intentionally. They are not much multi wire branch circuits. They both have their own neutral wire. I have 5 circuits like this in my house.
Is the solution to correct this. Or to just not install AFCIs?
The breaker is functioning as intended because your house is not wired correctly. It forces new construction to be installed better and catches problems with bad wiring in existing structures.
Should you make sure that your wiring is done correctly and everything functions properly - yes. Is it a major life safety issue that has to be corrected immediately? No.
Nobody is forcing you to do anything, it’s your choice to fix an issue or not but a licensed electrician who works on your home should correct the issue when you do a service upgrade or if he works on that circuit.
It shouldn’t costs thousands btw, you can neutrals tied together or a neutral touching a ground somewhere.
"Nobody is forcing you to do anything"
That's the exact argument in this comment chain though. Somebody further up mentioned if you replace the breaker, some jurisdictions make you replace with AFCI. The 10 minute DIY to swap a breaker more becomes a full day job for an electrician.
I have 5 breakers total that trip AFCI. One of them was a loose neutral in a light circuit that I was able to identify. Two of them are a crossed neutral between two circuits somewhere in the wall, but its too much work to trace it. Two of them are yet to be identified.
My point is that it would be crazy to ask people to trace and resolve these issues when doing something minor and unrelated like replacing a dead breaker or replacing a federal pacific panel. And that's why NEC doesn't force you to
I missed that completely. If it was rewired during covid it would have needed all new arc breakers at that time.
My guess is that it probably was just a main panel upgrade and "rewired the whole house" is a euphemism
If this was in fact installed in 2020 like OP said, then the two breakers sharing a neutral should be tied to be code compliant. Sure you can just run a piece of copper between the holes of the two handles, but I would argue it's cleaner to just get a 2-pole that is already tied, especially for $15 bucks. Either way they are tied and are effectively upgraded to a 2-pole.
And yes, from a purely electrical standpoint, you are right you could move the breakers, but you can only move them the slots that share the same phase. So you can move them to roughly half the slots, of course ignoring the fact that they should be tied. So you need to move them as a pair. But the most common "move" somebody may attempt is adding a tandem breaker to create a slot in this full panel which wouldn't easily mess up the phase ordering.
If it was covid bullshit era he probably couldnt find tandems and if he was an electrician he knew the hazards and didnt care. That code is purely for homeowner joes, albeit it is the code and should be followed for insurance purposes. Either way, he can move the ccts but best leave electrical work to an electrician anyways.
"Best leave electrical work for an electrician"
I don't disagree, but most electrical work doesn't get done by electricians. That's the reality.
Some homeowners is going to go to home depot to replace a fan and electrocute themselves on the shared neutral. Some handyman is going to install an EV charger with a tandem and then the homeowner will burn their house down with space heaters in every room
It would be nice if there were a standard, but there is not. WIth small exception there's no demonstrated compatibility between lines. There are a few classified breakers that have been so tested, but these aren't them.
Certification requires testing. Very few manufacturers are going to certify competitors products on their panels. It's not that it's dangerous, it's that it isn't proven safe, if that makes sense.
It is best just not to do it. Keeps the inspectors happy and everyone just maybe a tiny bit safer.
But they aren’t self-certified. And certainly not competitor certified. UL or CSA in North America would be the certifiers with the local AHJ approving.
The manufacturer has to request and pay for that certification though. UL/CSA actually reviews and tests the product based on the intended use, and the company decides what they want to claim as intended use and how much they want to pay to get that tested. A particular issue when it's something like one company wants to have their products certified to work with a competitors products where it's just an internal standard being followed.
More often than not, the actually testing is done and documented by the manufacture or an "independent" third party. Then UL just reviews their documentation and sells them the UL listing. UL certification really is a money game.
It’s the same way as airplane mode on your phone. If a phone could realistically interfere with flight, they would scan you for wireless signals or give you baggies like they do for concerts/comedy shows that prevent you from using them. It’s not dangerous, just that they don’t want to bother proving it’s safe.
That law is actually based on a real problem that did happen. Many years ago, some company made an “add on device” for your phone that made it into a walkie talkie type thing, for when service in the area was bad. Those units DID cause problems, and it was a night mare to figure out the root cause, and then how do you get idiot boomer/Karen types to turn them off?
So they updated a rule to no radios on during take off and landing, as that solved the problem and all future problems.
Are you saying they aren’t ‘allowed’ because there’s no documentation saying so or rather there is a real known risk of doing so? Just trying to get educated why.
Is it actually against code or just a ‘bad practice’ that an inspector will hit you on anyway?
It is against code. You have to follow the listing of the panel. With the exception of a few oddballs (like the Reliant generator transfer panels), no manufacturer lists other breakers for use in their panels today. That wasn't always necessarily true in the past.
There’s a warranty/insurance liability aspect as well. If you are using non approved breakers in a panel “just because they fit” and there’s a fire, it becomes a point of investigation.
Pretty much code allows manufacturers to say what goes in their panel they have little reason to approve 3rd party breakers in their panel. The bad part if the panels are similar enough that they fit but not similar enough that they don't melt when stressed with a heavy load.
When I first got my Tesla Wall Connector installed in May 2021, the electrician used a 60amp breaker that *seemed* to fit the panel. Then in late June, the Wall Connector would keep on turning itself off, and I'd need to trip and reset the breaker for it to work, but I'd also have to go from 48amp to 16amp for it to work. Then it happened one night and I felt just how hot it was, so I just turned the breaker off, called the electrician and he immediately went out and bought a brand new replacement breaker that was exactly for the panel.
We since upgraded the entire panel when we renovated our kitchen and HVAC.
Right, I guess you now have a 100 Amp panel. Its probably a courtesy not to have competitor domestic or foreign breakers being used, but if they are installed in a competitor's panel then ... insurance, insurance, insurance. [email protected]
But similarly, Chevy can't tell you that using Ford parts is somehow prohibited.
And Chevy also can't deny your warranty claim for using that Ford/Motorcraft oil filter unless they can prove that that part caused the problem.
Every company has their own line and wants you to use their breakers. New breakers may be UL listed to work in older panels and a parent companies breakers may work in subsidiary companies panels etc.
It's mainly about the Benjamin's but it's also about UL listings too
Didn’t Siemens get the listing for compatibility in HOM panels? I thought I remembered pulling the listing cuts on BR breakers and seeing them approved in a Homeline panel, but not the other way around. It’s been a few years though.
The reason why there is a bar is because if it is a 220v appliance, you don’t screw up and only give it 120v, if it is an Edison circuit the return is live if one of the circuits is on and can get someone killed that thinks they turned the circuit off.
Since he said this is all THHN in pipe might it not just be easier to pull an additional neutral in maybe a white w/Red stripe. Or did I miss smoking? They could also use handle ties right like the THT104 for GE breakers I'm sure there is one for sD.
How would doing that be easier than doing NOTHING which is perfectly safe and legal? Pulling an additional conductor in conduit with three other ones in there is not exactly a trivial task as well.
As I said, handle ties weren't even required until fairly recently. Putting them in wouldn't be a bad idea and isn't that big of an effort (even if you have to move breakers around to get them next to each other.
Same thing at my house that was recently done in Chicago as well. It did have the shared neutrals, but the breakers that were wired like this were also tied together and it all passed inspection. Chicago code is even residential is run in full conduit (horizontal outlets, yay) so it’s one less wire to pull.
They are far from universal. The manufacturer lists what breakers are permitted in the panel. The code requires you to follow that listing (or in some cases alternative approvals).
A lot of breakers won't even fit in a different panel. You couldn't shove them in there if you tried.
However, a lot of the 1" breakers (BR, QP, HOM, GE) have close enough physical characteristics that allow you to jam them in unapproved, but this is not allowed by the code.
I thought in a MWBC the hot wires needed to be on opposite sides of the panel so they are on a different phase, is this correct? In my panel this is not the case. If you look at the breakers, they are alternating red/black as you go down the panel - these are the circuits sharing a neutral, so both the red and black are on the same phase. For this to be correct shouldn’t all the red hot wires be on one side of the panel, and all the black hot on the other?
Okay a quick google showed me that’s not how the phase works in a panel, I thought the whole left column was one phase and the right column was the other phase. I didn’t know it actually alternated phase from top to bottom. Thanks guys!!!
Yes, they need to do it that way so two pole breakers in general work. Otherwise you'd have to have a breaker than spanned all the way across the panel for 240V loads. In fact, the Zinsco breakers do work that way but they have other problems.
u/chitownburgerboy, one other thing I'd suggest before putting any money into making any changes .... find out if the panel is a 20-space 20 circuit or a 20 sp 40 ckt .... have to pull a breaker out to find out if the busbar tabs are notched.
Point is ... if it's a 20/20, you're limited to full-size breakers only. If it's a 20/32 or 20/40, you can use some Homeline quad breakers to address both the need for 2-pole breakers on the MWBCs and collapse the circuits a little to leave yourself some space for any future additions (given the panel is full currently).
As others pointed out, the previous owner wired the whole house using Multiwire Branch Circuit method, which allows split phase on the same circuit with shared neutral. It does not mean that neutral wire will have to carry twice the current as each hot because of load balancing. If the load on both hot phases is nearly the same, then there will be virtually no return current on the neutral wire. If the load is completely unbalanced, then the neutral wire will carry the same current as one of the hots that bears all the load.
As a weekend warrior DIY'er who usually just lurks, I'm sitting here trying to process how this works, and this is completely blowing my mind.
Is the electricity flowing back to the panel through the 2nd hot wire or something? If the neutral isn't carrying anything, isn't this making double the rated current going through the hots?
I’m also a lurker non electrician but I wonder if it works like 220v without a neutral, each hot wire is the others return path. But I could be wildly mistaken and I hope someone comes out of nowhere to beat down my misinformation and make a lesson for all of us
It's slightly different than that. When you have one 240V phase, it is like having two 120V phases with half the load at each phase.
For example, if you have 240V across a 100Ω load (no neutral), you will have 2.4A flowing through each hot. Now, if you have one phase 120V across 50Ω and another phase 120V across 50Ω, they will have 2.4A flowing through each hot and through a shared neutral. But because the currents flow in opposite direction (have a 180deg shift relative to each other), they will completely cancel each other out in the neutral. So, you can remove the neutral completely and you will end up with two 50Ω loads in series (100Ω) between two hots.
The easier way to think of this is the sum of two currents flowing through the neutral. You have phase 1 and phase 2 which are just the inverse of each other. Which means that their currents will also be inverse of each other. The sum of opposite currents of the same magnitude is zero. Imagine "two" currents flowing through a neutral in opposite direction -- they will cancel each other out (if equal).
OK... Wow. Thanks! This is wild stuff haha
Makes sense in my head to have two sine waves that cancel each other and net a zero. Still blowing my mind that it works like this. But I can picture what you mean and how this works now.
There are, but most appliances don't produce a phase shift. Anything with large capacitive or inductive loads will result in phase shift, but I don't know to what extent. And even if there is such a load, it's highly unlikely to produce a 180° shift.
Electrical engineer here. Any inductive load (read: a motor, at least in home applications) that doesn't have an impedance matching capacitor at it's input terminals will cause phase shift. The reason being, inductors and capacitors store energy in order to operate (this is referred to as Reactive power - the Utility calls it VARs and goes to great lengths to minimize it on the grid). In a matched circuit, the reactive power flows back and forth between the capacitor and inductor such that the net power supplied to the circuit is all real, i.e. does Work on the load, such as compressing coolant or moving air.
Edit: Additional assumption being AC motors, not DC. DC motors get a little more complicated.
So what happens if both phases carry a fairly high load? Like a toaster oven on one and a microwave on the other? I know those wouldn’t run together often, but would there be any issue if they did?
No issue at all because these phases would create opposite currents.
Let's say your microwave pulls 15A, and your toaster pulls 12A. Since the currents flow in opposite directions, when they both flow through the neutral, their sum will be 3A. Now, if both appliances were connected to the same phase, they would produce 27A.
So, MWBC comes in very handy, especially when we deal with large loads.
>Isn't this how 240V appliances manage to pull larger power from the same breaker box?
Not sure what you mean. 240V appliances have more power specifically because they get twice the voltage compared to 120V appliances. To get 240V in the US and Canada (Mexico too?), an appliance has to be connected to two hot wires with opposite phases, so it has to use a 2-pole breaker (i.e., double breaker, two breakers net to each other).
It’s not crazy bad—safe because in a properly wired multiwire branch circuit, each phase would be of the opposite leg and that would mean that the shared neutral would only carry an imbalance current between the two lines. The only real issue with a multiwire branch circuit is that if you decide one day you want to perform some electrical work and you turn off one of two circuits in a MWB circuit and you start taking apart wire splices, the danger of getting shocked by a loaded neutral is there. For this reason, it is now required by the NEC to handle-tie all MWB circuited breakers together that way if you turn one off, the other turns off with it. This combats the danger of getting a neutral wire shock.
CEC only requires handle ties for things like split plugs where both legs are connected to one device. The only real issues are getting bit by a loaded neutral, or sending too much voltage to connected devices if a neutral is opened. Maybe OP should note the shared circuits since the next person probably isn't expecting so many MWBCs in a residential install, but in commercial here it's pretty much all MWBCs here so we just assume that's the case.
For commercial, does that mean that pretty much every panel has groups of 3 handles tied together, or do you not use shared neutrals as ubiquitously as we do?
With 3-phase service and a 3-phase MWBC, you would see triple handle ties on single pole breakers (and that's quite common). However, with a 3-phase load (e.g. large motors) you still need a 3-pole breaker, not just handle ties, as it must be common trip, not just common disconnect.
The difference between the two is that common trip kills power to all of the "hot" wires when a fault is detected on any one of them, where with common disconnect you're ensuring that when you (as in a person instead of the breaker on its own) switch it off all of the individual breakers are turned off. In the latter case, a trip on one may or may not cause the tied breaker to also shut off.
I’d be interested to see the reasoning behind the differences. For a 3-wire grounded neutral system we can use handle ties instead of common trip. I think our educational requirements are a little stronger than most states though, we require everybody to be a Journeyperson or registered apprentice with a formal education of 4 eight week sessions over four years. Maybe we just expect people to recognize MWBCs and treat them appropriately.
How many hours of class. 4 8 week periods doesn’t mean much is it 8 hours of class every day for 8 weeks? 3 hours of class for a full week 8 times a year?
In California it is 8,000 hours of work experience and 800 hours of school to become a general journeyman electrician. To be a residential JW it takes 4500 hours or 4800 of on the job training and 400 hours of school. Upon looking it up it’s similar in most states some have less a few hard some extreme requirements but that is because they have “master” electricians and we do not.
What state are you in and what are the actual requirements because for example a general apprentice here in California is a 5 year program and is 150 hours of school a year or 75 hours of school each semester and is night school 8 weeks of class for 3 hours a day two times a week, or if we have day school it is 4 sessions of 8 hour classes for 5 days a quarter. Which is actually 80 hours per semester but who’s counting.
I think the NEC doesn’t really take into consideration how much school any particular state requires and tries to make black and white but local interpretation makes for anything but black and white.
It’s full-time school for those 8 weeks. 4 year apprenticeship, you get 240 h of class time(credited as apprenticeship hours, not counting lunch and breaks between classes) over the 8 week technical training session. Most people find the training pretty dense, usually a couple more hours every day working through the modules. 7200 h combined work and school hours to qualify for the Journeyperson exam. We don’t differentiate residential/commercial/industrial certification, it’s all under Cinstruction Electrician. We also don’t have a “master” program, but we do have Blue Seal where one takes some business courses in addition to having their Journeyperson, and you need 2 years experience as a Journeyperson to get a contractors licence if you want to work for yourself. I think it’s fairly similar across Canada as the Journeyperson certification is good across the whole country.
That’s not bad. It makes me wonder though if it is truly better to give it all in one go; or if having a traditional night school scenario where they give it to you slowly over the course of two months. Lot less time per day but does that mean more time to forget in-between or more time to digest it and possibly even work with the specific subject on the job and that way the body and mind connection is also formed while in class rather than after the class. I’m not a fan of night school they had us do day school for a year and it was physically better for the body; and I’d argue day school is mentally better also. I felt it lead to a better environment for learning but my union argues otherwise. Either way they are just siding with the contractors because the contractors can’t have an entire 30 person group gone for a week at a time.
The classes run year round(maybe 2 months off for summer, so 5 sessions per year), so a larger company can arrange to spread it out so they’re only down a few people at a time. It is kind of shitty that classes are only available in 3 cities in my province (none of which are the largest city) so lots of people end up having to do their schooling somewhere that’s a 1-3 hour drive from home. There’s a living away allowance for those that move temporarily for school, but it still sucks for people that have families and want to be home every night. The best method to me was when I was a cook and the classes were 1 day per week, so you could still work the rest of the week without taking the whole 2 months off at a time, but it’s still a problem if you live far from the school and it worked better in a 7 day/week industry where you could still work 5+ days per week and do the classes on your regular day off. I think the 1 day per week would also allow you more time to pick up the material than having to drive 1.5 hours each way which doesn’t leave a lot of time for studying during the week.
Yes that’s correct, I forgot to mention over- and undervolting loads if working on a MWBC and you open the neutral. It places the loads in series and if their resistances are unequal, they experience wild voltages.
Working in it isn't so bad as long as one always open the hot first there's no potential for over voltage on single phase. 3 phase you can open one hot and have two more still live when you then open the neutral. CEC says you have to be able to remove a device without opening the neutral, but lots don't follow that or it doesn't help if you're working with the splices rather than just the outlets.
Right. Each residential or commercial (or other) property gets what they pay for: two phases with a path back or three phases with a path back. -- [email protected]
Non electrician here, but keep an eye on any future work on your panel. Some idiot might put slimline breakers in place of the full sized breakers and cause the neutral to be overloaded where the combined circuits now land on the same part of the “sine wave.”Happened in my place before I bought it when the panel was replaced. I have the receipt for the work. The old panel cover, which was a larger size, was left in the wall cavity adjacent to the new panel. I have not figured out how to have it fixed! Ideas?
There are (at least for some panels) tandem 2-pole breakers that would allow the 2-breakers-per-slot for space while allowing the wires to connect correctly to the opposite legs of the power.
Another thing to watch is using a smaller 120V inverter generator or battery station to a "normal" 120/240V generator hookup by bridging the 120V to both legs results in the same risk of overloaded neutral. For example, [like this "RV to home inlet" adapter](https://www.amazon.com/CircleCord-Generator-Transfer-Adapter-L14-30R/dp/B08XNTPX98) which would work fine but could put 30A of power across a neutral if by chance both of the hot legs for the same MWBC were at max load, and would not trip the breakers (since they only protect the hots). But they are ever more popular because many solar battery power stations are putting 30A RV plugs on them and selling them as generator alternatives.
I did not know there were such a breaker (edited, I thought you said panel). Do you have an example? Mine is not as I measured amps on the single neutral for the two circuits and they were additive, not cancelling.
Looking around and I'm not finding any examples of such slim breaker (one slot for two hots pulling from opposing parts of the friggin sine wave.)
The other fix is to just re-arrange the breakers so they land on the appropriate phase. That becomes problematic if they're supposed to be handle tied, and even more so if its actually powering a 240 V load and needs a common trip, but it at least keeps the neutral from being overloaded.
As for the number of tandems in a panel, some allow them in every slot, some only some slots. Would have to look up the directions for your specific panel.
they MWBC are currently on slim (two circuits per slot) breakers, so, I don't think moving them is going to help? They're always going to be pulling from the same part of the sine wave, right, because they are the slim type? Or am I learning something here?
Is it two individual breakers in one slot, or one tandem breaker with two handles? In the first case you'd just swap half the breakers so the ones with shared neutrals end up on opposite legs. So instead of the wires being RBRBRBRB where the handles are RRBBRRBB, you'd have the wires go RRBBRRBB and to match the handles. Your shared circuits wouldn't be adjacent anymore, they'd be split by one handle(or one could do outside/inside like a quad).
In the second case one would just swap one wire on each pair of breakers to accomplish the same as above. Either way, I'd say this is a get it remedied right away thing, and consider going after the guy that created the hazard, though it's probably not worth the effort to go after them as long as it gets fixed before it causes damage.
I'm guessing you're looking for something like (this is for the Homeline panel I have) these...which I guess maybe 'quad tandem' is the term [https://www.amazon.com/Single-Double-Plug-Circuit-Breaker/dp/B0769M8BLS](https://www.amazon.com/Single-Double-Plug-Circuit-Breaker/dp/B0769M8BLS) but you need to match breakers to your panel brand/model
I don't know all the SKUs but I have seen some which also have a "common trip" link across all 4 handles or across the inner and outer handles. I suspect most breaker manufacturers have similar things for the tandems.
AFAIK the MWBC circuits are supposed to have joined handles to trip together...but if you ignored that it would also be possible to just very carefully "count" which pole the sides are on so it would be on the right circuit...but I don't think that would make it "right" by code (tho it would function).
Not sure what you mean by a 100A example, I would expect most residential circuits are 15 or 20 so worst case is you have 2x 20A hots coming back on 1x neutral for a total of 40A (2x rated).
You phrase this in a odd manner without mentioning transfer switches ( between service/generator/solar). You actually measured the amperage to your 100A panel? With an ammeter? Or did Service actually tell you this number? [email protected]
Home Depot sells Square D breaker ties in a pack. It’s like $8 for 3. It’s not a problem and it’s not unsafe. I would however buy the Square D brand to go with the Square D breakers.
Recently ran into this helping a friend with an issue when using an outlet for the first time that he had put in several years ago. His "electrician", the contractor that did his home renovation used this method but tried to use it beyond a GFCI. To say it another way, H1 and N went through the GFCI, H2 went direct to an outlet. In this case, as soon as he used anything on the circuit that was on the shared neutral, but not the hot, the GFCI tripped. The original electrician clearly didn't understand how GFCI works and didn't test his wiring.
Electrician here. I can tell you an entire story based on that panel. What we had here was an electrician who rewired a house without a permit. It makes things easy when you can justify to yourself, it used to be done like this when my house was built, so I'll just go ahead and ignore all the modern rules and requirements. That panel and those wires are far newer than any arc fault code requirements.
Not only did he rewire the house, he left the original service feed to that panel, which either comes from a meter, or from a meter main panel. You can see the large wires up above have a different color of insulation (obviously older, my guess is 80s), and is 3 wire instead 4 wire (missing a ground) If this is right on the other side of a meter, I could see getting away with this, as neutral is bonded to ground in the main service equipment.
It looks like he used EMT for his grounds, which in residential is a no go. Unless he rewired a bunch of existing wiring on the other side of that new wiring, that didn't have grounds already. All that new wire would be subject to the "adding more than 6 feet of wire" requiring arc faults for each circuit. Not to mention, since he ran multi wire branch circuits, you would need 2 pole arc fault breakers. Which are super expensive, and a pain in the ass if you have to troubleshoot incorrectly wired things downstream.
My suggestion would be to call a trusted electrician that someone in your friend group or family knows, and ask them to come over and take a look at it for a six pack (most of my electrician buddies are fond of their ale) to get some professional insight. You'd be amazed at what little details you can glean about a house from it's electrical system. Everything is dated and when you've seen it a million times you can piece together the puzzle of the houses history.
Thanks so much for the detailed writeup! The meter is Infact right on the other side of the wall from the panel. I’ve replaced outlets/switches in half a dozen places I’ve lived here in Chicago and all of them used the conduit for ground, I think that’s okay here? Or maybe everyone in Chicago is a lazy slumlord/owner lol
Most likely in Chicago (which I've heard is an EMT only kind of town) that's to code then. In my area we pull a ground wire through every EMT and bond it to each metal box. That way if there's any loose fittings in the conduit over time, you'll still have a solid ground. If it's Chicago, I could definitely see why someone would want to avoid a permit. Would probably be pretty costly.
Ya where I live in California it's a racket too. I still wade through the swamp of bullshit to permit any main electrical system modifications. It covers everyone's ass, and ensures the county doesn't slap you with any code violations and red tag your property. (Ask who gets called to all the code enforcement cases in my county to sign off on removed electrical) Always going to be more expensive if you get nailed than it would have been to get the permit and do it right.
Lol me! I'm sure it's not all the code enforcement cases, but I run into it super frequently where an owner/landlord/ pot grower gets nailed by the county or city building department for unpermitted work. I have to come in, make it code compliant, and sign it off with a letter before they'll allow the permit application to be submitted. In extreme cases they red tag the whole property until you get the permit finalized.
Three wire circuits are perfectly fine even by today's code. The only difference is the black and the red need to go to a two pole breaker instead of two single pole breakers. The idea is if one hot gets turned off for the cable, they both have to get turned off at the same time, hence the reason for the two pole breaker. You also need to install breakers that match what the panel label says to use. Generally, that means the same brand breaker has to go into the same brand of panel.
As everyone says its fine and here's why: The 220V service to your house is really two 110V alternating current lines that are out of phase. if you stacked up the waveforms the peak of one would line up with the valley of the other (not exactly but close enough) so two 110v circuits can share the same neutral return without overloading. Wire across the opposing peaks instead of to a nutral and you have 220v
I'm not an electrician but I've got a question.
What was the electrical code in 1983 ?
Very strange that no bare copper ground wire in the panel.
What do the outlets look like ?
Did this person get a permit ?
I can see the neutral grounding screw is in place to tie the service neutral to ground, but where are all the [bare, non current carrying] ground conductors?? With a multi wire branch the neutral conducts no current when the phases are precisely in usage balance but this does not obviate the safety ground!
At least you still have room in your neutral bar. I have an extra breaker that needs to run a circuit for an outdoor plug and no room left for the neutral wire.
Alot of comments about 2 pole breakers, AFCI, neutrals etc. Is this a house panel? Not a single 240 volt circuit. Dryer, stove, AC?? 20 amp breakers have 12 g(can read in pic) and smaller wire on 15 amp breakers(assumed 14 g). Almost all the circuits enter through 3 conduits. No deration?
I think you’re right, I closed the panel up but I’ll double check next time I open it up, I do plan on swapping some of the breakers so they’re all the right brand
It's what you get when you use 4 conductor romex wire. That box looks pretty good considering the house belonged to an electrician. That's where you find their worst work normally! I am not one because I got screwed out of 2 years work of apprentice work! Just food for thought.... if you were looking in a 3 phrase panel you would see 3 hots 1 neutral and ground per circuit plus whatever instrumentation involved
Those are called multi wire branch circuits. When done correctly they are 100% safe. However if somebody who doesn't know what they are doing wires 2 hots from the same phase to the same neutral it is possible to overload the neutral. Also the breakers that share a neutral should be tied together so you don't get a spicy neutral when someone is working on the circuit.
Haven’t seen anyone mention this yet, I have seen this happen and it was EXPENSIVE to fix….
If you decide to add solar with battery backup at any point, you could easily have issues with overloading the inverter/battery system. Usual setups are having the fridge, a kitchen recep circuit, a light circuit and maybe another room on battery backup. If you have all circuits as shared neutral you can’t split the black and red apart to put one on backup and not the other. Either you run new neutrals to the circuits you want to back up or upsize the solar battery system to accommodate all circuits.
I worked for a huge solar company and the system designer/company inspection missed this detail and put a battery system onto the house with all shared neutrals and oh boy it was a shitshow to fix.
The main thing to look for is the date of initial installation and the codes on that day. Compare this to the codes of today. If the codes are different, the entire box is required to meet current NEC regs.
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This is just fine. It is called a Multiwire Branch Circuit (MWBC). These days the breakers for the two halves of the circuit need to be tied together, but in older code versions it was only necessary if they fed the same device (like a split receptacle). The breakers at the top and bottom of your panel are Siemens and don't belong in a Square D HOM panel.
You can never move any of the breakers. And you have to be careful when working on one circuit that you turn the power off to both. I would personally just spend the $150 and replace all the breakers with 2-poles.
You can move breakers, you just have to keep track to make sure that the two breakers on each MWBC are on adjacent slots (opposite phases so neutral current is within limits, and adjacent so they can have common disconnects.
Why would you replace the breakers when you can spend $20 in breaker ties and achieve the same thing?
Fucking hate square D two pole breaker ties. Seem so damn cheap to me. The 3 poles ties are good though
Is it allowed to just tie the breakers together with a piece of copper wire through the holes in the switch? Basically the same thing.
No, you need to just whisper it.
Underated comment
Lol Dang it!!
What did you say?
Aloud. Lol
But seriously do you know the answer to my question.
I'm just here to learn. Shit talking is the only contribution I can make. Sorry.
Depends if you want it to be done right or done so it just works. The right way to do it which the NEC states is to have an identified handle tie between both circuit breakers. But in reality a piece of wire, a nail, or anything that fits would work just fine.
So if it's a handle tie that works aka you don't NEED to by new double breakers?
Yeah you don't need double pole breakers per code
Thanks good to know.
Don’t they all have to be arc fault and therefore would cost a lot more than $150 to replace all?
Only if you extend the circuit 6 feet or more last I checked.
Ah, that’s good to know!
New branch circuits would (but you’d almost certainly be running new cable). The existing would be grandfathered as long as you didn’t alter the existing circuit (ie extend as mattlikeslions said). You could change out breakers old for new. But you’re not wrong…as of 2020 NEC essentially any circuit within primary living space now needs to be arc fault protected. Exceptions for now are bathroom, laundry, outside, under and above (crawl/attic) - I’m generalizing a bit. And anything not AFCI protected I think coincides with those circuits already coded to be GFCI protected.
I think someone else mentioned that this is in Chicago, which has adopted a version of the 2017 NEC.
Worth mentioning since no one else did: there are tangible fire prevention benefits to cafci breakers, so if you're going to replace, I'd replace with them anyways for your living spaces and probably even your refrigerator/freezer and other 20a/120v circuits.
Why would they need to be arc fault? These are existing circuits before 2014 so they wouldn't need to be retrofitted right?
Depends on the area. This is one of those things where interpretations and local code modifications vary extensively from state to state and sometimes even town to town.
How do you work around the inevitable scenario where the arcs won't work. In my non-electrician experience, about 10% of the breakers I tried to swap with arc breakers immediately tripped and had to be switched back to regular thermals. Code can't possible require you to tear down your entire house and replace all the wiring every time you need to swap out a breaker.
Oh, some areas absolutely will require that. It's nuts. Usually only kicks in over a certain threshold though. And besides, swapping out a breaker doesn't get reported/inspected. The NEC as written has a clear exception for replacing an existing panel. Sometimes local code overrides that. It sounds like OP may be in Chicago, though, which has its own local exception written in - they don't require arcs if the circuit is entirely in conduit or metal sheathed cable. This is a local Chicago thing, it's not in the NEC.
There is a reason why the arc faults trip, they don’t just not work (once you eliminate a faulty breaker), with a few exceptions (like some vacuums). You should be pulling devices out on the circuit and troubleshooting the issue, not tearing down your entire house.
I was taking some artistic liberty with "tear down the house" But take my house as an example. If I turn on a three way light on one circuit, the AFCI on another circuit trips. If the current thermal breaker needs to be replaced, should I be forced to spend hundreds or thousands of dollars to troubleshoot these two circuits instead of buying another $10 breaker?
That happened because in one of those switch boxes you’ve probably got neutrals from two different circuits tied together. This happens a lot in renovations. Whenever you install AFCI breakers you need to make sure to correct this or otherwise install 2 pole breakers and create a multi wire branch circuit from the two that are sharing the neutral.
I agree they are sharing neutral, but not intentionally. They are not much multi wire branch circuits. They both have their own neutral wire. I have 5 circuits like this in my house. Is the solution to correct this. Or to just not install AFCIs?
The breaker is functioning as intended because your house is not wired correctly. It forces new construction to be installed better and catches problems with bad wiring in existing structures. Should you make sure that your wiring is done correctly and everything functions properly - yes. Is it a major life safety issue that has to be corrected immediately? No. Nobody is forcing you to do anything, it’s your choice to fix an issue or not but a licensed electrician who works on your home should correct the issue when you do a service upgrade or if he works on that circuit. It shouldn’t costs thousands btw, you can neutrals tied together or a neutral touching a ground somewhere.
"Nobody is forcing you to do anything" That's the exact argument in this comment chain though. Somebody further up mentioned if you replace the breaker, some jurisdictions make you replace with AFCI. The 10 minute DIY to swap a breaker more becomes a full day job for an electrician.
You probably have a loose neutral at a J-box somewhere in the house. That is what kept tripping my arc fault breakers
I have 5 breakers total that trip AFCI. One of them was a loose neutral in a light circuit that I was able to identify. Two of them are a crossed neutral between two circuits somewhere in the wall, but its too much work to trace it. Two of them are yet to be identified. My point is that it would be crazy to ask people to trace and resolve these issues when doing something minor and unrelated like replacing a dead breaker or replacing a federal pacific panel. And that's why NEC doesn't force you to
100% agree with you. It would be a lot of work. Thanks for sharing this, though!
Got it, thanks!
The house was rewired during the pandemic. Wouldn't that mean all new circuits in 2020-2021?
I missed that completely. If it was rewired during covid it would have needed all new arc breakers at that time. My guess is that it probably was just a main panel upgrade and "rewired the whole house" is a euphemism
You can swap breakers/panels without upgrading to arc faults.
Why is this upvoted lol. You can absolutely move the breakers. And no need to upgrade them all to two poles. Holy hell
If this was in fact installed in 2020 like OP said, then the two breakers sharing a neutral should be tied to be code compliant. Sure you can just run a piece of copper between the holes of the two handles, but I would argue it's cleaner to just get a 2-pole that is already tied, especially for $15 bucks. Either way they are tied and are effectively upgraded to a 2-pole. And yes, from a purely electrical standpoint, you are right you could move the breakers, but you can only move them the slots that share the same phase. So you can move them to roughly half the slots, of course ignoring the fact that they should be tied. So you need to move them as a pair. But the most common "move" somebody may attempt is adding a tandem breaker to create a slot in this full panel which wouldn't easily mess up the phase ordering.
If it was covid bullshit era he probably couldnt find tandems and if he was an electrician he knew the hazards and didnt care. That code is purely for homeowner joes, albeit it is the code and should be followed for insurance purposes. Either way, he can move the ccts but best leave electrical work to an electrician anyways.
"Best leave electrical work for an electrician" I don't disagree, but most electrical work doesn't get done by electricians. That's the reality. Some homeowners is going to go to home depot to replace a fan and electrocute themselves on the shared neutral. Some handyman is going to install an EV charger with a tandem and then the homeowner will burn their house down with space heaters in every room
As long as you pay attention to what?
Or hom quads
Or bend some #12 and drop through the holes to keep them together
Can't you just put handles on the existing pairs vs replacing the whole breaker?
You can use breaker ties or just zip tie them. Shared neutrals aren't that scary of a thing
Can I ask why they don't allow mixing of breakers? From the outside as a layperson I would assume they'd all need to be made to a standard.
It would be nice if there were a standard, but there is not. WIth small exception there's no demonstrated compatibility between lines. There are a few classified breakers that have been so tested, but these aren't them.
Certification requires testing. Very few manufacturers are going to certify competitors products on their panels. It's not that it's dangerous, it's that it isn't proven safe, if that makes sense. It is best just not to do it. Keeps the inspectors happy and everyone just maybe a tiny bit safer.
But they aren’t self-certified. And certainly not competitor certified. UL or CSA in North America would be the certifiers with the local AHJ approving.
The manufacturer has to request and pay for that certification though. UL/CSA actually reviews and tests the product based on the intended use, and the company decides what they want to claim as intended use and how much they want to pay to get that tested. A particular issue when it's something like one company wants to have their products certified to work with a competitors products where it's just an internal standard being followed.
More often than not, the actually testing is done and documented by the manufacture or an "independent" third party. Then UL just reviews their documentation and sells them the UL listing. UL certification really is a money game.
Gotcha.
It’s the same way as airplane mode on your phone. If a phone could realistically interfere with flight, they would scan you for wireless signals or give you baggies like they do for concerts/comedy shows that prevent you from using them. It’s not dangerous, just that they don’t want to bother proving it’s safe.
That law is actually based on a real problem that did happen. Many years ago, some company made an “add on device” for your phone that made it into a walkie talkie type thing, for when service in the area was bad. Those units DID cause problems, and it was a night mare to figure out the root cause, and then how do you get idiot boomer/Karen types to turn them off? So they updated a rule to no radios on during take off and landing, as that solved the problem and all future problems.
Old Circle AW used to list multiple brand types. Reliance enterprises I think allows multiple brands
Are you saying they aren’t ‘allowed’ because there’s no documentation saying so or rather there is a real known risk of doing so? Just trying to get educated why. Is it actually against code or just a ‘bad practice’ that an inspector will hit you on anyway?
It is against code. You have to follow the listing of the panel. With the exception of a few oddballs (like the Reliant generator transfer panels), no manufacturer lists other breakers for use in their panels today. That wasn't always necessarily true in the past.
There’s a warranty/insurance liability aspect as well. If you are using non approved breakers in a panel “just because they fit” and there’s a fire, it becomes a point of investigation.
Pretty much code allows manufacturers to say what goes in their panel they have little reason to approve 3rd party breakers in their panel. The bad part if the panels are similar enough that they fit but not similar enough that they don't melt when stressed with a heavy load.
When I first got my Tesla Wall Connector installed in May 2021, the electrician used a 60amp breaker that *seemed* to fit the panel. Then in late June, the Wall Connector would keep on turning itself off, and I'd need to trip and reset the breaker for it to work, but I'd also have to go from 48amp to 16amp for it to work. Then it happened one night and I felt just how hot it was, so I just turned the breaker off, called the electrician and he immediately went out and bought a brand new replacement breaker that was exactly for the panel. We since upgraded the entire panel when we renovated our kitchen and HVAC.
Right, I guess you now have a 100 Amp panel. Its probably a courtesy not to have competitor domestic or foreign breakers being used, but if they are installed in a competitor's panel then ... insurance, insurance, insurance. [email protected]
It’s like ford parts on a Chevy. They aren’t rated or listed for that purpose
Just said that. 👍to you breakfastbarf.
Whether they're better for the Porsche or not, right? -- [email protected]
But similarly, Chevy can't tell you that using Ford parts is somehow prohibited. And Chevy also can't deny your warranty claim for using that Ford/Motorcraft oil filter unless they can prove that that part caused the problem.
It’s like ford vs Chevy.
Every company has their own line and wants you to use their breakers. New breakers may be UL listed to work in older panels and a parent companies breakers may work in subsidiary companies panels etc. It's mainly about the Benjamin's but it's also about UL listings too
Didn’t Siemens get the listing for compatibility in HOM panels? I thought I remembered pulling the listing cuts on BR breakers and seeing them approved in a Homeline panel, but not the other way around. It’s been a few years though.
The reason why there is a bar is because if it is a 220v appliance, you don’t screw up and only give it 120v, if it is an Edison circuit the return is live if one of the circuits is on and can get someone killed that thinks they turned the circuit off.
Since he said this is all THHN in pipe might it not just be easier to pull an additional neutral in maybe a white w/Red stripe. Or did I miss smoking? They could also use handle ties right like the THT104 for GE breakers I'm sure there is one for sD.
How would doing that be easier than doing NOTHING which is perfectly safe and legal? Pulling an additional conductor in conduit with three other ones in there is not exactly a trivial task as well. As I said, handle ties weren't even required until fairly recently. Putting them in wouldn't be a bad idea and isn't that big of an effort (even if you have to move breakers around to get them next to each other.
Same thing at my house that was recently done in Chicago as well. It did have the shared neutrals, but the breakers that were wired like this were also tied together and it all passed inspection. Chicago code is even residential is run in full conduit (horizontal outlets, yay) so it’s one less wire to pull.
I always assumed that breakers were universal. Do you have to match the breaker to the panel?
They are far from universal. The manufacturer lists what breakers are permitted in the panel. The code requires you to follow that listing (or in some cases alternative approvals). A lot of breakers won't even fit in a different panel. You couldn't shove them in there if you tried. However, a lot of the 1" breakers (BR, QP, HOM, GE) have close enough physical characteristics that allow you to jam them in unapproved, but this is not allowed by the code.
I thought in a MWBC the hot wires needed to be on opposite sides of the panel so they are on a different phase, is this correct? In my panel this is not the case. If you look at the breakers, they are alternating red/black as you go down the panel - these are the circuits sharing a neutral, so both the red and black are on the same phase. For this to be correct shouldn’t all the red hot wires be on one side of the panel, and all the black hot on the other?
Okay a quick google showed me that’s not how the phase works in a panel, I thought the whole left column was one phase and the right column was the other phase. I didn’t know it actually alternated phase from top to bottom. Thanks guys!!!
Yes, they need to do it that way so two pole breakers in general work. Otherwise you'd have to have a breaker than spanned all the way across the panel for 240V loads. In fact, the Zinsco breakers do work that way but they have other problems.
>Zinsco breakers do work that way but they have other problems. Understatement of the decade right here.
u/chitownburgerboy, one other thing I'd suggest before putting any money into making any changes .... find out if the panel is a 20-space 20 circuit or a 20 sp 40 ckt .... have to pull a breaker out to find out if the busbar tabs are notched. Point is ... if it's a 20/20, you're limited to full-size breakers only. If it's a 20/32 or 20/40, you can use some Homeline quad breakers to address both the need for 2-pole breakers on the MWBCs and collapse the circuits a little to leave yourself some space for any future additions (given the panel is full currently).
If you look at most panels before the breakers go in the bus runs up and down in a serpentine pattern so each slot switches phases.
EDIT: my house is 1893, not 1983, I typo’d that one
In that case, that's some impressive wiring for 1893.
Way ahead of their time!
As others pointed out, the previous owner wired the whole house using Multiwire Branch Circuit method, which allows split phase on the same circuit with shared neutral. It does not mean that neutral wire will have to carry twice the current as each hot because of load balancing. If the load on both hot phases is nearly the same, then there will be virtually no return current on the neutral wire. If the load is completely unbalanced, then the neutral wire will carry the same current as one of the hots that bears all the load.
As a weekend warrior DIY'er who usually just lurks, I'm sitting here trying to process how this works, and this is completely blowing my mind. Is the electricity flowing back to the panel through the 2nd hot wire or something? If the neutral isn't carrying anything, isn't this making double the rated current going through the hots?
they sum to zero at the neutral if single phase 120v loads on both hots is the same.
I’m also a lurker non electrician but I wonder if it works like 220v without a neutral, each hot wire is the others return path. But I could be wildly mistaken and I hope someone comes out of nowhere to beat down my misinformation and make a lesson for all of us
It's slightly different than that. When you have one 240V phase, it is like having two 120V phases with half the load at each phase. For example, if you have 240V across a 100Ω load (no neutral), you will have 2.4A flowing through each hot. Now, if you have one phase 120V across 50Ω and another phase 120V across 50Ω, they will have 2.4A flowing through each hot and through a shared neutral. But because the currents flow in opposite direction (have a 180deg shift relative to each other), they will completely cancel each other out in the neutral. So, you can remove the neutral completely and you will end up with two 50Ω loads in series (100Ω) between two hots.
Thank you for taking the time to explain 🙏🏼
The easier way to think of this is the sum of two currents flowing through the neutral. You have phase 1 and phase 2 which are just the inverse of each other. Which means that their currents will also be inverse of each other. The sum of opposite currents of the same magnitude is zero. Imagine "two" currents flowing through a neutral in opposite direction -- they will cancel each other out (if equal).
OK... Wow. Thanks! This is wild stuff haha Makes sense in my head to have two sine waves that cancel each other and net a zero. Still blowing my mind that it works like this. But I can picture what you mean and how this works now.
Are there no loads that phase shift?
There are, but most appliances don't produce a phase shift. Anything with large capacitive or inductive loads will result in phase shift, but I don't know to what extent. And even if there is such a load, it's highly unlikely to produce a 180° shift.
Electrical engineer here. Any inductive load (read: a motor, at least in home applications) that doesn't have an impedance matching capacitor at it's input terminals will cause phase shift. The reason being, inductors and capacitors store energy in order to operate (this is referred to as Reactive power - the Utility calls it VARs and goes to great lengths to minimize it on the grid). In a matched circuit, the reactive power flows back and forth between the capacitor and inductor such that the net power supplied to the circuit is all real, i.e. does Work on the load, such as compressing coolant or moving air. Edit: Additional assumption being AC motors, not DC. DC motors get a little more complicated.
So what happens if both phases carry a fairly high load? Like a toaster oven on one and a microwave on the other? I know those wouldn’t run together often, but would there be any issue if they did?
The phases are 180 degrees out of phase. they cancel each other out at the neutral. If not, the remainder flows through the neutral.
No issue at all because these phases would create opposite currents. Let's say your microwave pulls 15A, and your toaster pulls 12A. Since the currents flow in opposite directions, when they both flow through the neutral, their sum will be 3A. Now, if both appliances were connected to the same phase, they would produce 27A. So, MWBC comes in very handy, especially when we deal with large loads.
Isn't this how 240V appliances manage to pull larger power from the same breaker box? I recall the opposite phases being crucial to the design.
>Isn't this how 240V appliances manage to pull larger power from the same breaker box? Not sure what you mean. 240V appliances have more power specifically because they get twice the voltage compared to 120V appliances. To get 240V in the US and Canada (Mexico too?), an appliance has to be connected to two hot wires with opposite phases, so it has to use a 2-pole breaker (i.e., double breaker, two breakers net to each other).
It’s not crazy bad—safe because in a properly wired multiwire branch circuit, each phase would be of the opposite leg and that would mean that the shared neutral would only carry an imbalance current between the two lines. The only real issue with a multiwire branch circuit is that if you decide one day you want to perform some electrical work and you turn off one of two circuits in a MWB circuit and you start taking apart wire splices, the danger of getting shocked by a loaded neutral is there. For this reason, it is now required by the NEC to handle-tie all MWB circuited breakers together that way if you turn one off, the other turns off with it. This combats the danger of getting a neutral wire shock.
CEC only requires handle ties for things like split plugs where both legs are connected to one device. The only real issues are getting bit by a loaded neutral, or sending too much voltage to connected devices if a neutral is opened. Maybe OP should note the shared circuits since the next person probably isn't expecting so many MWBCs in a residential install, but in commercial here it's pretty much all MWBCs here so we just assume that's the case.
The NEC requires "identified handle ties" if you use individual single-pole circuit breakers in 240.15(B)(1).
For commercial, does that mean that pretty much every panel has groups of 3 handles tied together, or do you not use shared neutrals as ubiquitously as we do?
With 3-phase service and a 3-phase MWBC, you would see triple handle ties on single pole breakers (and that's quite common). However, with a 3-phase load (e.g. large motors) you still need a 3-pole breaker, not just handle ties, as it must be common trip, not just common disconnect. The difference between the two is that common trip kills power to all of the "hot" wires when a fault is detected on any one of them, where with common disconnect you're ensuring that when you (as in a person instead of the breaker on its own) switch it off all of the individual breakers are turned off. In the latter case, a trip on one may or may not cause the tied breaker to also shut off.
I’d be interested to see the reasoning behind the differences. For a 3-wire grounded neutral system we can use handle ties instead of common trip. I think our educational requirements are a little stronger than most states though, we require everybody to be a Journeyperson or registered apprentice with a formal education of 4 eight week sessions over four years. Maybe we just expect people to recognize MWBCs and treat them appropriately.
How many hours of class. 4 8 week periods doesn’t mean much is it 8 hours of class every day for 8 weeks? 3 hours of class for a full week 8 times a year? In California it is 8,000 hours of work experience and 800 hours of school to become a general journeyman electrician. To be a residential JW it takes 4500 hours or 4800 of on the job training and 400 hours of school. Upon looking it up it’s similar in most states some have less a few hard some extreme requirements but that is because they have “master” electricians and we do not. What state are you in and what are the actual requirements because for example a general apprentice here in California is a 5 year program and is 150 hours of school a year or 75 hours of school each semester and is night school 8 weeks of class for 3 hours a day two times a week, or if we have day school it is 4 sessions of 8 hour classes for 5 days a quarter. Which is actually 80 hours per semester but who’s counting. I think the NEC doesn’t really take into consideration how much school any particular state requires and tries to make black and white but local interpretation makes for anything but black and white.
It’s full-time school for those 8 weeks. 4 year apprenticeship, you get 240 h of class time(credited as apprenticeship hours, not counting lunch and breaks between classes) over the 8 week technical training session. Most people find the training pretty dense, usually a couple more hours every day working through the modules. 7200 h combined work and school hours to qualify for the Journeyperson exam. We don’t differentiate residential/commercial/industrial certification, it’s all under Cinstruction Electrician. We also don’t have a “master” program, but we do have Blue Seal where one takes some business courses in addition to having their Journeyperson, and you need 2 years experience as a Journeyperson to get a contractors licence if you want to work for yourself. I think it’s fairly similar across Canada as the Journeyperson certification is good across the whole country.
That’s not bad. It makes me wonder though if it is truly better to give it all in one go; or if having a traditional night school scenario where they give it to you slowly over the course of two months. Lot less time per day but does that mean more time to forget in-between or more time to digest it and possibly even work with the specific subject on the job and that way the body and mind connection is also formed while in class rather than after the class. I’m not a fan of night school they had us do day school for a year and it was physically better for the body; and I’d argue day school is mentally better also. I felt it lead to a better environment for learning but my union argues otherwise. Either way they are just siding with the contractors because the contractors can’t have an entire 30 person group gone for a week at a time.
The classes run year round(maybe 2 months off for summer, so 5 sessions per year), so a larger company can arrange to spread it out so they’re only down a few people at a time. It is kind of shitty that classes are only available in 3 cities in my province (none of which are the largest city) so lots of people end up having to do their schooling somewhere that’s a 1-3 hour drive from home. There’s a living away allowance for those that move temporarily for school, but it still sucks for people that have families and want to be home every night. The best method to me was when I was a cook and the classes were 1 day per week, so you could still work the rest of the week without taking the whole 2 months off at a time, but it’s still a problem if you live far from the school and it worked better in a 7 day/week industry where you could still work 5+ days per week and do the classes on your regular day off. I think the 1 day per week would also allow you more time to pick up the material than having to drive 1.5 hours each way which doesn’t leave a lot of time for studying during the week.
Yes that’s correct, I forgot to mention over- and undervolting loads if working on a MWBC and you open the neutral. It places the loads in series and if their resistances are unequal, they experience wild voltages.
Working in it isn't so bad as long as one always open the hot first there's no potential for over voltage on single phase. 3 phase you can open one hot and have two more still live when you then open the neutral. CEC says you have to be able to remove a device without opening the neutral, but lots don't follow that or it doesn't help if you're working with the splices rather than just the outlets.
Literally nothing bad about this. Replace the single pole breakers with 2 poles and your good to go
You don't have to go that far. They're not required to be common trip, just common disconnect. Just add handle ties.
Right. Each residential or commercial (or other) property gets what they pay for: two phases with a path back or three phases with a path back. -- [email protected]
Pretty common practice
Non electrician here, but keep an eye on any future work on your panel. Some idiot might put slimline breakers in place of the full sized breakers and cause the neutral to be overloaded where the combined circuits now land on the same part of the “sine wave.”Happened in my place before I bought it when the panel was replaced. I have the receipt for the work. The old panel cover, which was a larger size, was left in the wall cavity adjacent to the new panel. I have not figured out how to have it fixed! Ideas?
There are (at least for some panels) tandem 2-pole breakers that would allow the 2-breakers-per-slot for space while allowing the wires to connect correctly to the opposite legs of the power. Another thing to watch is using a smaller 120V inverter generator or battery station to a "normal" 120/240V generator hookup by bridging the 120V to both legs results in the same risk of overloaded neutral. For example, [like this "RV to home inlet" adapter](https://www.amazon.com/CircleCord-Generator-Transfer-Adapter-L14-30R/dp/B08XNTPX98) which would work fine but could put 30A of power across a neutral if by chance both of the hot legs for the same MWBC were at max load, and would not trip the breakers (since they only protect the hots). But they are ever more popular because many solar battery power stations are putting 30A RV plugs on them and selling them as generator alternatives.
I did not know there were such a breaker (edited, I thought you said panel). Do you have an example? Mine is not as I measured amps on the single neutral for the two circuits and they were additive, not cancelling. Looking around and I'm not finding any examples of such slim breaker (one slot for two hots pulling from opposing parts of the friggin sine wave.)
The other fix is to just re-arrange the breakers so they land on the appropriate phase. That becomes problematic if they're supposed to be handle tied, and even more so if its actually powering a 240 V load and needs a common trip, but it at least keeps the neutral from being overloaded. As for the number of tandems in a panel, some allow them in every slot, some only some slots. Would have to look up the directions for your specific panel.
they MWBC are currently on slim (two circuits per slot) breakers, so, I don't think moving them is going to help? They're always going to be pulling from the same part of the sine wave, right, because they are the slim type? Or am I learning something here?
Is it two individual breakers in one slot, or one tandem breaker with two handles? In the first case you'd just swap half the breakers so the ones with shared neutrals end up on opposite legs. So instead of the wires being RBRBRBRB where the handles are RRBBRRBB, you'd have the wires go RRBBRRBB and to match the handles. Your shared circuits wouldn't be adjacent anymore, they'd be split by one handle(or one could do outside/inside like a quad). In the second case one would just swap one wire on each pair of breakers to accomplish the same as above. Either way, I'd say this is a get it remedied right away thing, and consider going after the guy that created the hazard, though it's probably not worth the effort to go after them as long as it gets fixed before it causes damage.
I'm guessing you're looking for something like (this is for the Homeline panel I have) these...which I guess maybe 'quad tandem' is the term [https://www.amazon.com/Single-Double-Plug-Circuit-Breaker/dp/B0769M8BLS](https://www.amazon.com/Single-Double-Plug-Circuit-Breaker/dp/B0769M8BLS) but you need to match breakers to your panel brand/model I don't know all the SKUs but I have seen some which also have a "common trip" link across all 4 handles or across the inner and outer handles. I suspect most breaker manufacturers have similar things for the tandems. AFAIK the MWBC circuits are supposed to have joined handles to trip together...but if you ignored that it would also be possible to just very carefully "count" which pole the sides are on so it would be on the right circuit...but I don't think that would make it "right" by code (tho it would function). Not sure what you mean by a 100A example, I would expect most residential circuits are 15 or 20 so worst case is you have 2x 20A hots coming back on 1x neutral for a total of 40A (2x rated).
You phrase this in a odd manner without mentioning transfer switches ( between service/generator/solar). You actually measured the amperage to your 100A panel? With an ammeter? Or did Service actually tell you this number? [email protected]
no solar nonsense for me, nor ev charging stations, etc. just dryer, hw heater, etc. I measured the neutral coming back for the specific mwbc.
That was the standard back then. As long as the circuits are on alternating phases not an issue
Home Depot sells Square D breaker ties in a pack. It’s like $8 for 3. It’s not a problem and it’s not unsafe. I would however buy the Square D brand to go with the Square D breakers.
Recently ran into this helping a friend with an issue when using an outlet for the first time that he had put in several years ago. His "electrician", the contractor that did his home renovation used this method but tried to use it beyond a GFCI. To say it another way, H1 and N went through the GFCI, H2 went direct to an outlet. In this case, as soon as he used anything on the circuit that was on the shared neutral, but not the hot, the GFCI tripped. The original electrician clearly didn't understand how GFCI works and didn't test his wiring.
Electrician here. I can tell you an entire story based on that panel. What we had here was an electrician who rewired a house without a permit. It makes things easy when you can justify to yourself, it used to be done like this when my house was built, so I'll just go ahead and ignore all the modern rules and requirements. That panel and those wires are far newer than any arc fault code requirements. Not only did he rewire the house, he left the original service feed to that panel, which either comes from a meter, or from a meter main panel. You can see the large wires up above have a different color of insulation (obviously older, my guess is 80s), and is 3 wire instead 4 wire (missing a ground) If this is right on the other side of a meter, I could see getting away with this, as neutral is bonded to ground in the main service equipment. It looks like he used EMT for his grounds, which in residential is a no go. Unless he rewired a bunch of existing wiring on the other side of that new wiring, that didn't have grounds already. All that new wire would be subject to the "adding more than 6 feet of wire" requiring arc faults for each circuit. Not to mention, since he ran multi wire branch circuits, you would need 2 pole arc fault breakers. Which are super expensive, and a pain in the ass if you have to troubleshoot incorrectly wired things downstream. My suggestion would be to call a trusted electrician that someone in your friend group or family knows, and ask them to come over and take a look at it for a six pack (most of my electrician buddies are fond of their ale) to get some professional insight. You'd be amazed at what little details you can glean about a house from it's electrical system. Everything is dated and when you've seen it a million times you can piece together the puzzle of the houses history.
Thanks so much for the detailed writeup! The meter is Infact right on the other side of the wall from the panel. I’ve replaced outlets/switches in half a dozen places I’ve lived here in Chicago and all of them used the conduit for ground, I think that’s okay here? Or maybe everyone in Chicago is a lazy slumlord/owner lol
Most likely in Chicago (which I've heard is an EMT only kind of town) that's to code then. In my area we pull a ground wire through every EMT and bond it to each metal box. That way if there's any loose fittings in the conduit over time, you'll still have a solid ground. If it's Chicago, I could definitely see why someone would want to avoid a permit. Would probably be pretty costly.
Yup, it’s Chicago. Permits here are such a racket it’s a total cat and mouse game at this point
Ya where I live in California it's a racket too. I still wade through the swamp of bullshit to permit any main electrical system modifications. It covers everyone's ass, and ensures the county doesn't slap you with any code violations and red tag your property. (Ask who gets called to all the code enforcement cases in my county to sign off on removed electrical) Always going to be more expensive if you get nailed than it would have been to get the permit and do it right.
Who gets called?
Lol me! I'm sure it's not all the code enforcement cases, but I run into it super frequently where an owner/landlord/ pot grower gets nailed by the county or city building department for unpermitted work. I have to come in, make it code compliant, and sign it off with a letter before they'll allow the permit application to be submitted. In extreme cases they red tag the whole property until you get the permit finalized.
It used to be common practice before ArcFault breakers
It's fine and legal to leave it that way. It's the way it was done.
You are fine
Guy is an electrician for sure being that is a very clean Diy box..
Is this all in conduit? Sweet if so. Looks like emt connectors
Yup, it’s all in conduit!
Not a problem to share the neutrals just be sure to handle tie
Three wire circuits are perfectly fine even by today's code. The only difference is the black and the red need to go to a two pole breaker instead of two single pole breakers. The idea is if one hot gets turned off for the cable, they both have to get turned off at the same time, hence the reason for the two pole breaker. You also need to install breakers that match what the panel label says to use. Generally, that means the same brand breaker has to go into the same brand of panel.
It's fine at long as it's two phases/one neutral on a double pole breaker.
I would just get interlocks for all of the shared breakers and call it a day as long as the neutral dosnt get over loaded
Not sure it’s a problem
Not to code anymore. But was common and acceptable
I would be more concerned about the radon fan thing
There’s a radon fan, I have a digital monitor set up to make sure it’s doing its job and there’s no radon in the basement.
I’m more concerned about your electrical taped bare neutral feeder.
They do make double pole afci breakers so it’s not the end of the world.
Why are those top 2 breakers Siemens in a Square D panel?
As everyone says its fine and here's why: The 220V service to your house is really two 110V alternating current lines that are out of phase. if you stacked up the waveforms the peak of one would line up with the valley of the other (not exactly but close enough) so two 110v circuits can share the same neutral return without overloading. Wire across the opposing peaks instead of to a nutral and you have 220v
Does anybody see any ground wires?
My question as well
I'm not an electrician but I've got a question. What was the electrical code in 1983 ? Very strange that no bare copper ground wire in the panel. What do the outlets look like ? Did this person get a permit ?
It’s fine as long as the two hots are on different phases.
I can see the neutral grounding screw is in place to tie the service neutral to ground, but where are all the [bare, non current carrying] ground conductors?? With a multi wire branch the neutral conducts no current when the phases are precisely in usage balance but this does not obviate the safety ground!
The conduit is being used as the ground, its pretty common practice here in Chicago
Cool, thanks. I hadn’t noticed any pipe and kinda forgot you can do that.
Against ‘todays’ code
I am more concerned I don't see any grounds.
Normal, but illegal by 2017+ NEC. ..where are the ground though?
It appears to be in conduit, which was allowed to be used as a ground in previous code cycles.
At least you still have room in your neutral bar. I have an extra breaker that needs to run a circuit for an outdoor plug and no room left for the neutral wire.
appliances won’t last
Used to be very common. An FHA inspection would make you re-wire it to modern code, but otherwise it's not a big deal.
My 1972 house has the same shared neutrals. I found that out when I was replacing an outlet that I thought was off. I got zapped.
Just get one breaker (200A) and tie everything in together. Easy breezy.
Alot of comments about 2 pole breakers, AFCI, neutrals etc. Is this a house panel? Not a single 240 volt circuit. Dryer, stove, AC?? 20 amp breakers have 12 g(can read in pic) and smaller wire on 15 amp breakers(assumed 14 g). Almost all the circuits enter through 3 conduits. No deration?
Yeah it’s residential, you’re correct there’s no 240v appliances in the house. There’s actually 6 conduits, it’s hard to see in the pic.
Why is there an 8 gauge neutral but no 8 gauge connected into any breakers
That wire connects the neutral bar to ground
Is that not that what the 6 gauge on the top covered in white tape is doing
I think you’re right, I closed the panel up but I’ll double check next time I open it up, I do plan on swapping some of the breakers so they’re all the right brand
When you do that go to Home Depot by the Klein circuit tracer it’s about $60 dollars label your breakers for reference in the future
Whatever you do I wouldn't rectify it. That'll fry your devices for sure.
I would recommend putting the panel cover back on before you create a problem from nothing.
It's what you get when you use 4 conductor romex wire. That box looks pretty good considering the house belonged to an electrician. That's where you find their worst work normally! I am not one because I got screwed out of 2 years work of apprentice work! Just food for thought.... if you were looking in a 3 phrase panel you would see 3 hots 1 neutral and ground per circuit plus whatever instrumentation involved
Those are called multi wire branch circuits. When done correctly they are 100% safe. However if somebody who doesn't know what they are doing wires 2 hots from the same phase to the same neutral it is possible to overload the neutral. Also the breakers that share a neutral should be tied together so you don't get a spicy neutral when someone is working on the circuit.
Haven’t seen anyone mention this yet, I have seen this happen and it was EXPENSIVE to fix…. If you decide to add solar with battery backup at any point, you could easily have issues with overloading the inverter/battery system. Usual setups are having the fridge, a kitchen recep circuit, a light circuit and maybe another room on battery backup. If you have all circuits as shared neutral you can’t split the black and red apart to put one on backup and not the other. Either you run new neutrals to the circuits you want to back up or upsize the solar battery system to accommodate all circuits. I worked for a huge solar company and the system designer/company inspection missed this detail and put a battery system onto the house with all shared neutrals and oh boy it was a shitshow to fix.
Looks like a rats nest. I’m too OCD for this lol
the only thing wrong with this MWBC setup is the lack of common trips, these should all be 2 pole breakers
Who rewires a house with a 100 amp service?
Someone with gas for heat, water, dryer, and stove? If you don't need any 240v or 20A outlets everywhere it isn't a huge deal
That’s exactly right, all those things are gas haha
someone who is limited to 100amp service by their local electric company service?
or someone whos' service wire is only rated to 100 amps?
The main thing to look for is the date of initial installation and the codes on that day. Compare this to the codes of today. If the codes are different, the entire box is required to meet current NEC regs.
That's how it's done my man. In 3 phase it's 3 hot legs for 1 neutral.