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I recently asked for help because my dishwasher was tripping the circuit at random points in the cycle a few times last week. It was suggested to switch the breaker for another to see if it was a faulty breaker causing the issue since the appliance was new and well under 20amp power requirement: Faulty breaker? Older than the others?

So i finally started the process of switching the GFCI breakers today (after not using the dishwasher the rest of the week). The neutral wire on the breaker in question is burned! It has even burned into the coil on the breaker, which the neutral was touching. The live wire is fine.

Neutral

burned coil

In the picture, i have reinserted the neutral in the correct way, under the metal plate. But when i took it out originally, it was attached between the screw and the plate - you can see this bit of the plate is burned too. All the other breakers seem to have the wire screwed in correctly. Seems pretty dangerous to have left this breaker badly installed since it seemed to have created a fire risk.

For now i have put it back with the breaker switched off. I assume this is safe since now there is no power running to the neutral wire.

So could it have been an incorrectly or loosely installed neutral wire causing the shorting? I guess in this case, I can cut back the burned neutral wire and replace the breaker with a new one. Or could it be something else - do i need an electrician to investigate?

Thanks

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  • It would have been useful, when you noticed the improperly installed and burned wire, to observe it in action briefly before correcting it. If it was very loosely installed and arcing, that might explain the burning. And if these are AFCI breakers (you wrote GFCI) it would explain the tripping too. Try running the dishwasher now for a couple of cycles while you keep a close eye on it (not literally close of course). If you seem to have fixed the problem, is there enough slack in that neutral wire to cut it back to where it's good? – jay613 Apr 3 at 21:48
  • Has anything else lost power when the DW tripped? I could understand overheating of the neutral due to a loose connection at the breaker, but have no idea how you could get the burn marks on the pig tail. Where they there before, or recent?....like after you moved the DW to another circuit? Where you running other high current appliances at the same time, like a toaster or mircrowave? The only explanation I could come up with for the burn marks on the pig-tails is a mis-wired MWBC, overloading the neutral. – George Anderson Apr 3 at 22:01
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    Sorry - to clarify - the pig tail was touching the neutral - the burn was the neutral burning in to the pigtail. – excessliquidity Apr 3 at 22:05
  • Too late for me to edit my previous comment, thinking thru this, I don't see how a MWBC could cause this, esp. if on GFCI. It would trip instantly. I'm probably missing something, and others with more experience than me might be able to come up with a better possible answer. – George Anderson Apr 3 at 22:09
  • @excessliquidity ummm....your latest comment doesn't make a lot of sense. For one thing, the pig tail IS the neutral, and next, there is insulation on the pig tail that would have prevented contact, unless it was very defective. – George Anderson Apr 3 at 22:11
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Most likely, the neutral wire connection failed because the wire was not properly torqued down. Even experienced electricians cannot set a torque any more reliably then their spouses - that's been tested. It's why Code now requires use of torque screwdrivers.

The connection got hot, passing heat down the circuit neutral (copper is a very good thermal conductor), enough to cause thermal damage to adjacent wires. Note the damage to the neutral pigtail.

So, this failure does not condemn the GFCI breaker. It certainly does not disparage the other GFCI breakers.

Switching breakers will fix it, because you'll be unscrewing and re-screwing the screws, changing the torque setting. You'll probably be luckier this time.

Unfortunately the breaker that had the burnt-up wire is toast. The heat was at the wire-breaker contact point, and if it was hot enough for heat to walk down the copper wire and burn other wires, it was also hot enough to ruin the breaker plastics, gut the GFCI electronics, or throw the thermal bi-metal strip out of calibration. Into the trash it goes.

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