Spent 4 hours chasing a ground fault that was hidden in a junction box behind drywall

I was working on a commercial job in Portland last week, a small office remodel, and kept tripping a GFCI breaker on a lighting circuit. After testing every outlet and switch I thought I'd narrowed it to a bad wire in a junction box, but it turned out someone had buried a box behind the drywall during a previous reno and the ground wire was touching the box. Has anyone else run into a buried box like that or did I just get unlucky on a Monday?

2 comments

2 Comments

tessawebb24d ago

Three years back I found a junction box buried behind a drop ceiling tile that someone had just left floating on the drywall mud. My personal theory is that half the ground faults in the world are actually just someone's old bad decision hiding in a wall. Take that with a grain of salt though, because last week I spent two hours chasing a phantom issue that turned out to be a loose screw in my own meter.

simonreed24d ago

Yeah, I get that a lot of hidden junction boxes are definitely someone's old mess. But I don't think they're causing half the ground faults out there. Most ground faults I've run into come from wet locations or old wiring that's just worn out, not hidden joints. If anything, I'd bet the biggest culprit is cheap outlets and switches that fail after a few years.