Mixed Up Neutrals

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zcanyonboltz

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I am working on a house that had several home runs coming into panel from a junction box I've yet to find. While doing service upgrade I had to splice these conductors in a gutter and then to panel. They are multiwire branch circuits run in EMT with THHN. The grounded and ungrounded conductors were not grouped together in panel when I arrived and still are not.
Here are my thoughts, the problem can arise when someone shuts of a breaker and begins working on a circuit only to still have neutral current on circuit because the neutral could be associated with a circuit that is still live. Another problem that could arise is at the panel or in a junction or device box a neutral is disconnected from a circuit that is still live and a live circuit loses neutral but keeps its hot. Is this thinking correct anything I'm missing?
One thing I did is put a couple circuits I know where they go on a two pole breaker and only connected one neutral from the panel to them. This is on 2017 code so as long as I don't extend the circuit over 6 feet I don't need AFCI protection. Thanks.
 
I'm not sure what your actual question is, but you must not randomly mix up the neutrals. Cut and splice one at a time to avoid mis-connecting them.

You can trace a wire with a toner to identify it without cutting it.
 
My question is am missing anything else as other than what l listed in OP as far danger of these neutrals not being grouped together with correct hot? These conductors were never grouped together just all randomly landed in panel from a previous remodel 50+ years ago. They go to a j box l am looking for....this house is 110 years old , the jbox they go to is buried somewhere behind 1..5" thick pine paneling in a cieling. Once l find j box l can continuity test and group conductors from there. Thanks for idea of toner. I was going to run fish tape and try to get an idea of j box location.
 
Trying to follow, so you have one conduit from the panel to a jbox, then multiple conduits from there on with multiple neutrals in each of those conduits? As long as you have one for one to the existing neutrals to that point, you don’t have to worry about pairing, but if existing pairing is screwed up past that point, then that could be a problem, but from the sounds of it, you were just extending the existing, which all terminate at the same neutral bar. If they went to different panels, then you would have a problem.
 
zcanyonboltz said:
My question is am missing anything else as other than what l listed in OP as far danger of these neutrals not being grouped together with correct hot? These conductors were never grouped together just all randomly landed in panel from a previous remodel 50+ years ago.
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With multiwire branch circuits you also have to make sure that you are balancing the hots between the two phases. If the hots are on the same phase then the shared neutral can be overloaded because the currents add instead of subtracting.
 
To answer you directly, you can either test and group circuit conductors or turn off the whole panel if a neutral must be disturbed.

Why might a neutral need to be disturbed?
 
I have 8 neutrals and 9 hots coming out of panel and into a gutter. From the gutter these conductors enter house. . I have one hot that has no neutral, so l've got to pick which neutral and hot to put this one hot with. Someone pointed out l remember now if l dont phase multiwire branch circuit the neutral carries double. Even if l pull another neutral home run to gutter l dont have a way to get it to the j box till l find this j box. A neutral could be disturbed in future if someone is working on these circuits and I don't correctly group two of the hot conductors with the correct neutral there could be a problem.
 
zcanyonboltz said:
I have 8 neutrals and 9 hots coming out of panel and into a gutter. From the gutter these conductors enter house. . I have one hot that has no neutral, so l've got to pick which neutral and hot to put this one hot with. Someone pointed out l remember now if l dont phase multiwire branch circuit the neutral carries double. Even if l pull another neutral home run to gutter l dont have a way to get it to the j box till l find this j box. A neutral could be disturbed in future if someone is working on these circuits and I don't correctly group two of the hot conductors with the correct neutral there could be a problem.
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One hot with no neutral? Are you sure it’s not a 240 volt circuit, or it’s a 120/240 volt circuit ( if so, both hots should be in the same pipe) if you connect the new neutrals to the same old neutrals, it shouldn’t change the pairing down the line.
 
hillbilly1 said:
One hot with no neutral? Are you sure it’s not a 240 volt circuit, or it’s a 120/240 volt circuit ( if so, both hots should be in the same pipe) if you connect the new neutrals to the same old neutrals, it shouldn’t change the pairing down the line.
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But that does assume that whoever did the original wiring did it correctly.
 
zcanyonboltz said:
I have 8 neutrals and 9 hots coming out of panel and into a gutter. From the gutter these conductors enter house. . I have one hot that has no neutral, so l've got to pick which neutral and hot to put this one hot with.
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It sounds like you probably have one MWBC (3-wire, 2 hots and 1 neutral). I assume that you don't already have a 2-pole breaker or 1-poles with a handle tie for this circuit as required, based on what you stated above.
You could apply loads on the branch circuits and use a clamp meter on the neutral wires, one at a time, to find which neutral has the current changed by two of the 1-pole breakers instead of just one of them. That neutral and the conductors to those breakers will form the MWBC.
While doing this you can also find the other hot and neutral conductors that need to be paired and identified as in 200.4(B). A circuit tracer could also be used for this as mentioned above.
 
Thanks for the replies. I know it's not a 240-volt circuit the only 240 in the house is the dryer and I know where that's at. The problem with me hooking them back up wire for wire is that they were all landed on the neutral bar on the service I removed. Several of the hot conductors were also double lugged on circuit breakers. There was no way to keep them straight. I removed the conductors from the neutral bar and their respective breaker and pulled them up from the old panel into a gutter and then spliced them back down to new panel.
 
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You need a metal fishtape and a helper with good hearing to find the box. Once you do, you can identify conductors for grouping by simply pulling back and forth as you number them or tape them together.
 
LarryFine said:
You need a metal fishtape and a helper with good hearing to find the box. Once you do, you can identify conductors for grouping by simply pulling back and forth as you number them or tape them together.
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Thanks. I was thinking I was going to need to continuity test all of the conductors but moving them back and forth will go a lot better.
 
I wonder if a temperature sensor would work? I would think the j-box has a some heat in it


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zcanyonboltz said:
Thanks for idea of toner. I was going to run fish tape and try to get an idea of j box location.
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If you run a steel fish tape into the J-box, you can put the toner on the tape and search until you find the end of the tone. That will give you a good idea of where the box is.
 
I was thinking of just listening for a banging sound. The length pushed in would be a big clue, too.

I'm betting it's in a difficult-to-crawl crawl space.
 
zcanyonboltz said:
My question is am missing anything else as other than what l listed in OP as far danger of these neutrals not being grouped together with correct hot?
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One thing that I would consider by assuring my efforts were safe is realizing that all the neutrals regardless simply need to go to the neutral bar of the new panel same goes for all grounds, the important part where your liable is making sure the branch wires sharing a common neutral are on separate phases. don't want to heat a 20A rated neutral with 30-40 amps
 
Let's not forget the possibility -- now or in the future -- of GFCI and AFCI breakers, where the neutral conductor must be landed on the same breaker as the line conductor(s).
 
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