GFCI outlet tripping from lightning strike?

[Snip]

In my pole barn style shop, all of my 120v outlet runs have a GFCI outlet as the first device in the run. 6 or 7 different runs each on their own 20a breaker. If we have a very close lightning strike ( hear and see flash at the same time, more often than I would like,lol) one of the GFCI's will trip, same one every time. This is the run the beer and brisket fridge/freezer was on. Thought it might have something to do with the fridge but last night the fridge was plugged into a different run and the outlet that always tripped did. Nothing was plugged into that run that tripped. Any ideas why just this one trips and none of the others do?

 

[Toolfool]

Replace that GFCI outlet.

 

[cannuck]

See post #2.

When a lightning strike hits a conductor it has to find a route to ground. Big transformers have "lightning arrestors" (insulators ahead of the transformer that will break down and pass current at any voltage higher than what the transformer has been tested to withstand). There are usually "strike counters" on the transmission line side (and sometimes distribution), letting you know how many times voltage has exceeded some set point. But if the strike is between you and the transformer (i.e. on your distribution line) there is no such protection/isolation or if there is, your line to the pole top still sees a really big spike.

What I (the mechanical guy in a very high voltage world) have learned from repairing HV stuff is that the spike of current and voltage in a lightning strike can and will find a LOT of ways to bleed to ground. My best guess is your GFCI receptacle was one of those paths, and once current has tracked over an insulator it often leaves a carbon track behind that normal line voltage will leak through (called PD - or partial discharge or in some cases a "bolted fault" i.e. full load straight to ground) and the GFCI will see that and trip as it was likely a PD path.

 

[Snip]

Thank you both, I will replace that outlet. The shop is a dry shop unless I spill something, no inside plumbing but is still under an open electrical permit (slow working homeowner) so it will be another GFCI unit.

Kinda makes sense as this started after a lighting/tree strike last year about 400-450' south of the shops panel. House is between strike and shop and on a separate feed and meter. Strike entered house thru underground gas line and burnt thru stove flex line, small fire behind stove. Glad we were home and got it out in short order.

Second strike since we have lived here. Neighbors tell us of at least 2 others on our property in their lifetimes.

Did I mention that I am no longer a fan of lightning ? I also sit in the back row at church.

 

[wyliesdiesels]

Wow you should make sure your grounding electrodes and GECs are up to snuff

 

[Toolfool]

The first year we lived here in Florida (2019) we had lightning strike a pine tree in our front yard. I just happened to be watching the storm out the front window. LOUD crack and watched the bolt hit the tree and tear the bark in a spiral pattern down the trunk and into the ground. Right next to our well house. Our lights immediately went out. The next morning we began to assess the damage. Well pump fried, every GFCI in the house fried, TV fried, computer UPS's fried, half the breakers in the panel tripped, washing machine main board fried, A/C transformer fried, septic pump fried. A very expensive split second.

 

[wyliesdiesels]

Sounds like your grounding system was not up to snuff....

Radio towers for dispatch centers have been hit and not one thing in the building was damaged...

 

[Zeke]

For folks in lightening zones would it be helpful to upsize the GEC and add rods? Just thinking of the size of the typical SEC and typical #8 GEC. I for sure don't understand lightening. Living hard in the city there are too many structures and distribution to attract lightening to a specific spot such as a tree. Golf courses being an exception.

 

[wyliesdiesels]

For folks in lightening zones would it be helpful to upsize the GEC and add rods? Just thinking of the size of the typical SEC and typical #8 GEC. I for sure don't understand lightening. Living hard in the city there are too many structures and distribution to attract lightening to a specific spot such as a tree. Golf courses being an exception.

yes upsize GEC, make sure everything is bonded, add more electrodes etc you want everything at the same potential so lightning will just want to follow the direct path to earth instead of going through other equipment to get there

when i used to do motorola R56 grounding at microwave and cell phone towers, we had to put in so many rods and do tons of cad welds... they were always a major project just for the grounding...

theres a reason why you hardly ever hear about cell phone or microwave towers, PSAPs- public safety answering points (aka 911 dispatch centers, which often have their own towers for transmitting and receiving audio on public safety radio systems) and associated equipment getting fried due to a lightning strike

 

[mike93lx]

I wouldn't be plugging a fridge or freezer into a gfci.

I'd also replace the tripping gfci. I bet the problem goes away

 

[Snip]

I wouldn't be plugging a fridge or freezer into a gfci.

I'd also replace the tripping gfci. I bet the problem goes away

Still under an open permit (home owner). IIRC the 1st outlet on each circuit needs to be GFCI per the inspector. I need to get all buttoned up and get a final. I am going to pick up another outlet next time we get into town.

 

[mike93lx]

Still under an open permit (home owner). IIRC the 1st outlet on each circuit needs to be GFCI per the inspector. I need to get all buttoned up and get a final. I am going to pick up another outlet next time we get into town.

We do what we have to. I hear you.

The inspector is right. I just wouldn't leave it like that. I'd also want a fridge on a dedicated circuit, if possible. No need to have something else tripping the breaker and not noticing.

 

[Zeke]

Unless he uses a pilot light he still won't know if the fridge is going or not. If the fridge can be placed at the first recep and the GFCI installed at the next one, he is almost compliant.

That's why conduit is nice. Run that dedicate circuit to anywhere the conduit goes.

 

[toplessHO]

The first year we lived here in Florida (2019) we had lightning strike a pine tree in our front yard. I just happened to be watching the storm out the front window. LOUD crack and watched the bolt hit the tree and tear the bark in a spiral pattern down the trunk and into the ground. Right next to our well house. Our lights immediately went out. The next morning we began to assess the damage. Well pump fried, every GFCI in the house fried, TV fried, computer UPS's fried, half the breakers in the panel tripped, washing machine main board fried, A/C transformer fried, septic pump fried. A very expensive split second.

welcome to the lightning capitol