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Discussion Starter · #1 ·
So I'm scratching my head and could use some help. As the title said, we had a lightning storm a couple weeks ago and I noticed that the circuit break my refrigerator is plugged into tripped. From what I can tell, the breaker feeds 3 outlets (no, it is not dedicated, and also not a GFI). I tried resetting it, and it tripped again immediately. I had a spare breaker so I swapped it out and it seemed to work, but then tripped about an hour later. I suspected a problem with the fridge or my coffee maker so I unplugged everything from that circuit and plugged the appliances into another circuit. Everything was fine until I plugged something into the original circuit and it tripped immediately. I went out and bought a brand new breaker and swapped that in and got the same result (tripped once I plugged something in).

At this point I replaced all 3 receptacles on the circuit, and with the breaker off checked for continuity between hot and neutral (none) and well as hot and ground (none). Turned the breaker back on and all seemed well for a few hours and then it tripped again.

At this point I unplugged everything and methodically went 1 outlet at a time and plugged something in. Each time, no matter what outlet I used or what I plugged into it, the breaker eventually tripped. If I leave nothing plugged in, it doesn't trip.

So, I'm at a loss. The best explanations I can come up with are:

  1. I got very unlucky and had 3 back breakers in a row
  2. There is an intermittent short somewhere - like maybe a mouse is randomly bumping into an exposed wire in the wall
  3. There's an issue with the bus bar where this particular breaker mounts
Any ideas or advice would be greatly appreciated!

Thank you
Charlie
 

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Have you tried plugging in some other appliances into that circuit other than the refrigerator and coffee maker? If it still trips with a completely different load, that would point to something wrong with the circuit. If it doesn't trip, then it could be the appliances.

It's possible that a surge from the lightning damaged the refrigerator or coffee maker such that one or the other (or both) are now slightly overloading the circuit. A slight overload won't trip the breaker immediately, but can take many minutes before it trips.

If you have something like a Kill-A-Watt meter, it would be worth measuring how much power each of them is drawing.
 

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There is a high resistance fault in the insulation of the wires of that circuit. A continuity checker will not show that because the voltage it places on the wires is too low. The fault is occurring after the circuit has been on for a time and the wire has heated a little and expanded enough to make solid contact at the place were the lightning blew that hole in the insulation. If you open the splices between all of the cable sections except the segment attached directly to the breaker and the first receptacle you can then run something like your refrigerator off of that receptacle and see if it faults out again. Then you add the next segment of cable back in and see if that segment will carry it's loads. Last you add the segment to the third outlet and see if that holds. If all 3 hold for hours but then the breaker trips later consult a witch doctor or call in an electrician who owns a megohmmeter. A megohmmeter applies a higher test voltage to the conductors to detect any failure in the insulation. With a megohmmeter you can test each segment of cable and find which one has the insulation fault in it.

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Tom Horne
 

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Any chance there is another receptacle inside or out ,in basement. Does the circuit feed lights or something else

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To eliminate breaker/bus stab issues, temporarily relocate the breaker in your panel even if you have to swap with another breaker.
 

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Discussion Starter · #6 ·
Have you tried plugging in some other appliances into that circuit other than the refrigerator and coffee maker? If it still trips with a completely different load, that would point to something wrong with the circuit. If it doesn't trip, then it could be the appliances.

It's possible that a surge from the lightning damaged the refrigerator or coffee maker such that one or the other (or both) are now slightly overloading the circuit. A slight overload won't trip the breaker immediately, but can take many minutes before it trips.

If you have something like a Kill-A-Watt meter, it would be worth measuring how much power each of them is drawing.
Thanks. I did try this, the circuit blows regardless of what is plugged in, and I did the inverse (plugged fridge and coffee maker into another circuit and they have been running happily for several weeks.

There is a high resistance fault in the insulation of the wires of that circuit. A continuity checker will not show that because the voltage it places on the wires is too low. The fault is occurring after the circuit has been on for a time and the wire has heated a little and expanded enough to make solid contact at the place were the lightning blew that hole in the insulation. If you open the splices between all of the cable sections except the segment attached directly to the breaker and the first receptacle you can then run something like your refrigerator off of that receptacle and see if it faults out again. Then you add the next segment of cable back in and see if that segment will carry it's loads. Last you add the segment to the third outlet and see if that holds. If all 3 hold for hours but then the breaker trips later consult a witch doctor or call in an electrician who owns a megohmmeter. A megohmmeter applies a higher test voltage to the conductors to detect any failure in the insulation. With a megohmmeter you can test each segment of cable and find which one has the insulation fault in it.

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Tom Horne
I've never heard of this, but it certainly would explain what is happening. Thank you, I will try isolating the bad section per your suggestion.

Any chance there is another receptacle inside or out ,in basement. Does the circuit feed lights or something else

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It is possible, but I haven't been able to find anything else on that circuit. I've gone through the house and tested outlets and lights when the breaker is off and haven't found anything else that isn't working.

To eliminate breaker/bus stab issues, temporarily relocate the breaker in your panel even if you have to swap with another breaker.
Good idea. I'll try this as well.
 

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Have you checked outside ,attic, basement, crawlspace,outside in the eve of the house,any outside lighting on a switch or dusk till dawn activated.

After you confirm there aren't any other plugs or devices and haven't found a the issue.

Find the last plug or switch / device and disconnect from circuit and Work back towards the Electrical panel where the circuit begins.

I'm sure you have tightened down your neutrals correct.



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Discussion Starter · #8 ·
Have you checked outside ,attic, basement, crawlspace,outside in the eve of the house,any outside lighting on a switch or dusk till dawn activated.

After you confirm there aren't any other plugs or devices and haven't found a the issue.

Find the last plug or switch / device and disconnect from circuit and Work back towards the Electrical panel where the circuit begins.

I'm sure you have tightened down your neutrals correct.



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Thanks, I'm pretty much 100% sure there's nothing but those 3 outlets on the circuit. To eliminate the bus bar as the problem I swapped the hot leads between the breaker that was tripping and one that hasn't been. So far neither have tripped - but earlier it was close to a week between breaker trips. Once one trips, I'll know if its an issue with the circuit itself or the bus bar. I'm assuming its the circuit, and intend on tracing back as you recommended by disconnecting outlets.

Cheers
Charlie
 

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The lightning burned through the insulation and the wires are touching each other, or ground, loosely?
This fault you may find with an ordinary DVM on the megohm range.
 
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