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?

3 comments

3 Comments

tessawebb2mo 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.

simonreed2mo 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.

riley5811d ago

Gary over in Tulsa told me about a ground fault he chased for three days last summer. Turned out the previous owner had buried a junction box behind some paneling in the basement, and the tape just rotted off over time. That box was definitely the culprit, but @simonreed is right that most of the ones I hear about are just outlets in a damp garage or a bad wire nut on a thirty year old ceiling fan. He said the annoying part was he'd already replaced all the cheap outlets in that circuit before he found the hidden box.