Question about troubleshooting a phantom voltage on a 3-way switch loop

I spent nearly 4 hours yesterday chasing a 40-volt reading on a dead circuit in a 1978 split-level, only to find it was induced voltage from a parallel run in the same conduit. I kept thinking it was a bad neutral or a partial short, but my Fluke T+Pro kept picking it up. Has anyone else run into this with older cloth-wrapped wire, and what's your go-to method to confirm it's just induction before you start tearing into walls?

3 comments

3 Comments

patricia_wells1mo agoTop Commenter

Oh man, I feel your pain on that one. Four hours is rough but I've definitely been there too, staring at a reading that makes no sense with older wiring like that. The cloth wrapped stuff from the 70s can hold onto induced voltage like crazy, especially if runs are parallel. What I do now is switch my meter to low impedance or use a wiggy, that always kills the ghost reading and shows me what's real.

blake3022mo ago

Ever wasted a day on phantom voltage?

-1

robin4892mo agoMost Upvoted

Phantom voltage's annoying but @blake302, a whole day seems like a lot. It's usually a quick check with the right tool. Maybe the problem was something else.