Knob & Tube Neutral vs Hot with NO POWER

bash_bob

I have part of a branch circuit that is still wired with K&T. It has a fixture and two receptacles and is behind closed walls, but wired from an accessible attic. To start with, re-wiring them isn’t really what I want to be my only option. Most of the other K&T in the house has been removed/replaced. In the attic, part of the circuit was being rewired into NM cable. In the process I lost track of the hot & neutral connections of the K&T. So now,...

Originally asked by Jared Spaulding on Stack Exchange (diy) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

Remove light bulbs from fixtures. Unplug anything from all outlets on the circuit. Verify no continuity between the two wires in the attic. Anything connected to the circuit will drain the battery and make measuring voltage difficult or impossible. Connect a small, low voltage battery, such as a 9V battery, to the wires in the attic. Check polarity (by measuring DC voltage) of lamp sockets. Remember to switch them on if you try one and get no voltage. If wired correctly/consistently, all the center contacts should be connected to hot, and all the threaded shells should be connected to neutral. So if all the center contacts are the + side when measuring voltage, the + terminal of the battery...

Full answer by Ecnerwal: https://diy.stackexchange.com/a/333592 (CC BY-SA 4.0).

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