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Spent 6 hours last Tuesday chasing a ground fault on a 12 zone panel in Beaverton
Customer called at 7am saying the keypad was showing fault on zone 4 and beeping every 30 seconds, so I figured it was a simple door contact. Got there and the contact was fine, meter read 0 ohms on the loop, so I started pulling wires one by one at the panel. Turned out a romex staple from when the basement was finished in 2019 had nicked the jacket on the zone 7 wire, and it was bleeding 40 volts of AC into the whole bus. If you've run into gremlin faults like this, do you trust a megger or just start cutting and re-splicing?
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moore.beth14d ago
That staple story is the same thing as when you find one dead bulb killing a whole string of Christmas lights, one tiny thing takes down everything downstream. I've seen it with 2019 builds around here too, framers rushing and clipping wire right to the stud without a plate. On the megger question, I'd say it depends on how old the wiring is, on new romex a megger will scream at you over stuff that isn't even a real fault. My rule is meter first, then isolate zones at the panel, and only reach for the megger when the reading is weird and I'm out of easy splits. Cutting and re-splicing is fine but if you don't find the actual nick you'll be back in three months, so did the staple turn out to be right at the panel or out in the run somewhere?
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