Unexplained voltage on switchleg

[Sean_Carb]

We have a switch leg leaving a switch box going directly (supposedly) to a can. When 110v is applied to one of the legs, 55v comes back on the other leg and ground wire (ground being disconnected). When voltage is applied to the other leg, the same thing happens. No continuity between conductors, no continuity to ground, and no devices are installed. Any ideas??

 

[GoldDigger]

We have a switch leg leaving a switch box going directly (supposedly) to a can. When 110v is applied to one of the legs, 55v comes back on the other leg and ground wire (ground being disconnected). When voltage is applied to the other leg, the same thing happens. No continuity between conductors, no continuity to ground, and no devices are installed. Any ideas??

If you are using a high impedance meter, then the voltage you measure on the ground (EGC) wire could easily be just capacitively coupled stray voltage, of no particular concern.
The fact that it is symmetric at half the applied voltage supports that.

But I would do DC continuity tests and isolation tests just to be sure unless I had a meter available with a low input impedance to verify that.

 

[Sean_Carb]

If you are using a high impedance meter, then the voltage you measure on the ground (EGC) wire could easily be just capacitively coupled stray voltage, of no particular concern.
The fact that it is symmetric at half the applied voltage supports that.

But I would do DC continuity tests and isolation tests just to be sure unless I had a meter available with a low input impedance to verify that.

Thanks for the input. What do you mean by isolation test?

 

[GoldDigger]

Thanks for the input. What do you mean by isolation test?

Just make sure that there is no continuity where you do not expect to see it.

 

[iwire]

This explains it a bit more

http://www.nema.org/Technical/Documents/Bull_88_reaffirmed_12_15_11.pdf

But basically your meter does not put enough load on the circuit for what you are doing.

I suggest a knopp k60 for basic line voltage troubleshooting.

http://www.knoppinc.com/tools.htm

Or a digital meter with a low impedance feature.

 

[RLyons]

I'm confused by the use of the word "legs"??? Is this a 3-way?

 

[John120/240]

We have a switch leg leaving a switch box going directly (supposedly) to a can.

I'm confused by the use of the word "legs"??? Is this a 3-way?

The way I read his description he has power at the switch. "switch leg" is just that the switched conductor going to the can light. Around here for three way we use "travelers" and "point"

 

[RLyons]

The way I read his description he has power at the switch. "switch leg" is just that the switched conductor going to the can light. Around here for three way we use "travelers" and "point"

Then he mentions "applying voltage to other leg"

 

[John120/240]

The way I read his description he has power at the switch. "switch leg" is just that the switched conductor going to the can light. Around here for three way we use "travelers" and "point"

Then he mentions "applying voltage to other leg"

Maybe the OP has disconnected both black and white from source power. Maybe in trouble shooting he sends power to the light on black then measures the white. Then reverse the procedure. I do not know