TIL my old Fluke 87V meter was giving me a false ground reading in a 1960s house

I was checking a circuit in a house built in 1962 and kept getting a weird voltage between neutral and ground, like 12 volts... spent almost four hours checking every outlet on the line. Turns out the old cloth wiring had a shared neutral on a different circuit that was backfeeding through my meter. Has anyone else run into a ghost voltage that took forever to track down?

3 comments

3 Comments

oliver71920d ago

That "ghost voltage" thing. I've seen it a few times. Your meter was probably reading right, it was just picking up induced voltage from that shared neutral run. Those old cloth wires bundled together for decades act like a capacitor. My old Simpson would do the same. A low impedance test or just putting a small load on it makes it vanish.

hannahhayes20d ago

Oh man, you nailed it. I was losing my mind over a reading on a supposedly dead circuit last month. My fancy digital meter showed like 50 volts just hanging there. Threw a test light on it and poof, nothing. It's exactly that capacitive coupling from the old bundled wiring. Makes you doubt your gear for a second.

ninabutler1d ago

My Fluke 87 read 32 volts on a disconnected switch leg last Tuesday. I grabbed my old solenoid tester and it just clicked once then showed zero. It's wild how those old BX cables can hold a charge like a tiny battery.