Neutral issues. Residential.

[Qwertytfc]

I had a situation on some can lights that were flickering. It is fed from a 2 wire without ground home run. When I test the Hr I get 120v hot to neutral and used a pen tester to verify that the black conductor was the hot wire. I then in the junction box for the center fan and the first can light tied all my hot conductors together which fed the switch down on white and back on black. I would read between 30v and 120v from any disconnected neutral coming from cans, receps and unknown cables of constant power back to the known HR neutral even with the switch off(fan is tied to constant power and is switched with a remote). Can someone clarify why im getting between 30 v and 120v testing from outgoing neutrals to the known homerun neutral? I was using an auto ranging digital multimeter. Thanks.

 

[GoldDigger]

Most likely what you are seeing is called phantom voltage. It results from capacitive coupling between the conductor you are measuring and adjacent hot conductors in conduit or NM. This coupling can only deliver a very small current, and so the voltage you see will only be read using a high impedance meter. A low impedance meter or a solenoid tester ("wiggy") will either not read anything or will only read a few volts.

 

[Dennis Alwon]

If you are testing from hot to a neutral of a can then you are reading thru the bulb from the hot side. Is the switch a dimmer?

 

[Qwertytfc]

Not a dimmer switch.

 

[Qwertytfc]

And I was testing from outgoing neutrals to the home run neutral.

 

[ActionDave]

And I was testing from outgoing neutrals to the home run neutral.

So the 120V reading is likely reading the loaded neutral from one of the fixtures to neutral going back home. The 30V you could get testing between whatever neutral and a table leg.

 

[kwired]

if the switch is off you are reading capacitive coupled voltage, that is where you are seeing the 30 volts or anything up to 120.

If the switch is on you are reading open circuit voltage, and this will be full 120 volts when you have open circuit.

If you have a solid state switching device (dimmer) or even an illuminated switch, then you have continuity through the switching device even when it is "off" that will result in some let through, how much depends on exactly what you have and/or where it is set to.