Voltage reading to disconnected wire

[ExpertNoob]

Hello all, I've decided to add some recessed ceiling lighting to my living room. Since my living room light switch is currently wired to energize an outlet (house built in the 60s) I will be adding the new lights to the 20A breaker circuit that only has a single front porch light on it. My front porch light was wired with the hot wire straight to the light fixture and the neutral wire through the light switch. I've disconnected the wires from the light fixture and light switch. These disconnected wires read 0v to ground and neutral. However, if I touch one lead to 120v and the other to either disconnected wire it reads about 100v. Neither wire has continuity to ground or to each other, even on the 200M Ohm scale. I don't understand why this is happening and I obviously don't want to use this circuit if it has a short. Any ideas?

 

[MacGyverS2000]

Induced voltage from nearby live wires...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[waross]

You are using a very high impedance tester.
You are probably looking at the charging current of the wires capacitance to ground. A very low current times the very high impedance of your meter gives about 100 Volts.
Just for fun, try connecting the wires together and see if the indicated voltage changes.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ExpertNoob]

So if I read 100v from 120 to my disconnected wires, then the disconnected wires must have a 20v induced voltage from adjacent wiring? I will try connecting the two and see if the reading changes. Thank you for your input.

 

[itsmoked]

If you want proof take a drop light or neon test light and use it to jumper between them. You'll likely see nothing happen but the voltage difference will disappear.

Keith Cress
kcress -

http://www.flaminsystems.com