Learned the hard way about grounding in old homes yesterday

I was installing a wireless panel in a house built in 1922 near downtown Cleveland. The meter showed a weird fluctuation that turned out to be 14 milliamps of stray voltage on the ground wire. Called an electrician buddy and he told me old knob and tube wiring can still carry current even after it's disconnected. Now I always check grounding with a multimeter before mounting anything. Anybody else run into phantom voltage on older installs?

2 comments

2 Comments

alices1621d ago

1922 house near Akron last month had me chasing a phantom 8 volts on a disconnected line. Pulled an old switch plate and found cloth wrapped wire that was still warm to the touch. Had to rip out three sections of knob and tube that were running behind the plaster and sharing a junction box with modern Romex. The stray voltage was enough to make my meter dance but not enough to trip a breaker, drove me nuts for an afternoon. Now I keep a non contact voltage tester on me for every old house job, saved my bacon twice since then.

ericfox21d ago

Man that sounds like a nightmare, I’ve been there with old wiring that just won’t behave. Stray voltage is the worst because you know something’s wrong but it’s not obvious enough to catch quickly. Glad the non contact tester has been paying off for you, those things are a lifesaver in old houses.