Thought I had a bad GFCI but something else is going on - Help!

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Jim Goodman

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I need to give some background first:

On my property, I have a freestanding garage with a 1 bedroom apt. over it. I use the garage as a workshop. It is separately metered and has a 200 amp service. The garage is a 3-car garage with a 16' wide overhead door and an 8' wide overhead door. It's about 25 years old

1. There is a 20 amp receptacle in the ceiling for each door, with one of them being a 20 amp GFCI and the other being fed through the GFCI, so both are protected. I have a garage door opener only on the 16' wide door. The 8' door is still opened manually. These 2 receptacles are on one circuit. No other receptacles are on that circuit.

2. I have 20 amp receptacles at workbench height on 3 walls (not the doors' wall). There is one 20 amp circuit that serves half those receptacles and one 20 amp circuit that serves the rest. In each of these 2 groups of receptacles, the first receptacle is a 20 amp GFCI, and the remaining receptacles are fed from that first GFCI in the group.

3. This garage was on the property when we bought it. The previous owner had an electric dryer and washing machine in the garage. The dryer had its own 240-volt circuit and plug and the washing machine had its own, individual, 20 amp GFCI on its own circuit, with no other receptacles on that circuit. That washing machine receptacle is in the middle of the long back wall of the garage, about 4' beyond the last receptacle of the first group of 20 amp workbench receptacles, and about 4' from the first (GFCI) receptacle of the 2nd group of 20 amp workbench receptacles. i have my power miter saw plugged into this former washing machine receptacle.

4. We had some severe thunderstorms in the last week and on one day, in particular, we had multiple lightning strikes very close by.....like instant thunder after the flash.

OK, that's the relevant background, I think. So, today I went up to the garage for the first time since those thunderstorms. When punched in the code to open the door, it opened very slowly and the light on the opener did not come on. Turns out it was running on battery power. I tested the ceiling GFCI that the opener was plugged into and there was no power. I tried pushing the reset button and it would not click like they normally do. I pushed the test button and it would not move. I tested the other receptacle that was dead too. I checked the breaker in the panel and it was NOT tripped. I then took an extension cord and connected the door opener plug to one of the workbench receptacles, and all was good. Both workbench receptacle circuits were hot and the garage door opener worked perfectly......so nothing is wrong with the opener. But now, I discovered that the single, washing machine GFCI which I use to run my miter saw was also dead, and neither the test button nor reset button worked. I went online and read that GFCIs will go bad over time, and I figured that surges from the lightning strikes had fried them so I went and bought a new GFCI for the ceiling garage door circuit and one for the old washing machine/miter saw single receptacle circuit. I replaced the washing machine/miter saw GFCI and.....no power. It's still dead. With the breaker on in the panel, I pulled the new receptacle out of the box and took my Fluke 117 meter, set it to A/C voltage check, and touched my red lead to the hot (black) wire and common lead to first, the white neutral and secondly, to the ground, and in both cases, the meter read approximately 27.5 volts. I then took my meter and checked one of the receptacles on one of the two workbench circuits, and it read 120 volts. Next, I took off the panel cover and flipped off the breaker for the washing machine/miter saw circuit. NOTE, I have not removed any breakers from the panel in any of my attempts to diagnose this. Anyway, to continue, I touched the red lead to the terminal on the breaker and the common lead to the ground bar in the panel. The meter read 0.00 volts. Next, I flipped the breaker on and tested it again, and this time it showed 27.5 volts.....same as at the GFCI. So, then I repeated this test on other breakers, and some of them read 120 volts and some read 27.5 volts. I also have some open lugs in the panel and tested them, and some were 120 volts and some were 27.5 volts.

I can do basic wiring safely and know my limitations. I don't fully understand electricity and I have a healthy respect for it. But I am totally lost as to what is going on with this situation. Up until that storm the other day, everything worked perfectly and now I have two dead circuits and don't know what to do next. Is this something simple that my ignorance is making me miss or do I need to get an electrician in to figure this out? Thanks for any help.


SOLVED - Utility company came out and we've lost a leg of utility power. They will be burying a new cable next week. Thanks.
 
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wwhitney

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To pick out the (I think) important details, at the panel, for most circuit breakers, with the breaker off, you get no voltage reading between the breaker hot screw and the neutral or ground bus, and with the breaker on, you get 120V. But for the two affected circuits, with the breaker off you get no reading, but with the breaker on you get a reading of 27.5V.

That certainly sounds like bad breakers. Are those breakers AFCI or GFCI? If regular breakers, I'm not sure how a lightning strike would cause that sort of failure mode on just a couple breakers.

Cheers, Wayne
 

Reach4

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Is this perhaps a 2-pole breaker, or is it two 1-pole breakers?

If a 2-pole, then this is probably driving a MWBC (means shared neutral in effect). In that case, I can envision the breaker OK, but tripping due to an imbalanced current flow. For current to flow, there would be a short to something or another.
 
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