GFCI/lightening

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I had a lightning strike hit an antenna mast and it took out a lot of
electronics in my house. It actually popped circuit breakers in the
house along with taking out the TV, modem, KVR switch, low voltage LED
lighting, and several power supplies.

The interesting thing was the circuit for the Ground Fault outlet that
feeds my outdoor workbench was kaput, but didn't show any signs of
being fried. The GFCI didn't trip or turn off - the circuit breaker
on the workbench tripped but the GFI was still passing power to it.

Something to bear in mind - you are supposed to press the test button
once a month on those things to see if they are functioning. They can
malfunction in a way that leaves them lethal.

 

The lightning strike wasn't a ground fault, why should it trip ?

Now AFTER, the current surge if there was anything plugged into it could cause an insidious fault and you would never know. Any current drain with that type of voltage spike can weld the contacts of a breaker together rendering it a piece of wire.

And, when this struck, the path to ground caused an EMP in the house. Check EVERYTHING. Wash a load of clothes for example. Check ALL the functions on anything that appears to work. Any solenoids (like water valves in the washer) or relays, (stereo, microwave) anything with a coil. With an EMP each conductor becomes a generator and a coil is a bunch of wires all in series and can rally do some voltage. They get a weird type of leakage, there is only one way to test it, put the coil voltage to it and see if it actuates. No ohmmeter or anything can tell you. I think it is a gradual leakage between many windings. Whatever it does not pull.

 

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On Sat, 24 Aug 2019 18:03:50 -0700 (PDT), jurb6006@gmail.com wrote:

The lightning strike wasn't a ground fault, why should it trip ?

Now AFTER, the current surge if there was anything plugged into it could cause an insidious fault and you would never know. Any current drain with that type of voltage spike can weld the contacts of a breaker together rendering it a piece of wire.

And, when this struck, the path to ground caused an EMP in the house. Check EVERYTHING. Wash a load of clothes for example. Check ALL the functions on anything that appears to work. Any solenoids (like water valves in the washer) or relays, (stereo, microwave) anything with a coil. With an EMP each conductor becomes a generator and a coil is a bunch of wires all in series and can rally do some voltage. They get a weird type of leakage, there is only one way to test it, put the coil voltage to it and see if it actuates. No ohmmeter or anything can tell you. I think it is a gradual leakage between many windings. Whatever it does not pull.

I rigged a 10K ground fault (hot to ground via the resistor) on a 3
wire cord and checked the other GFI's.

I also did a post-mortem on the GFI that failed and found one 1/4 watt
resistor that fried and no other visible problems. The contacts
weren't welded and I could mechanically trip it once I had the works
opened up.