# Strange Electrical Question - a bit long

• posted on June 26, 2003, 1:37 pm
I have an older house in SE PA and am observing something with an electrical circuit that it not intuitively clear to me. First let me describe my panel configuration;
The feed into the house comes into a main circuit breaker box. There is a sub panel hanging off the main breaker panel. Out of this sub panel is fed (among other things) a 20-amp circuit feeding some recessed lighting fixtures and ceiling fan in my den.
The circuit comes straight from the sub panel to a junction box in the ceiling. From there it feeds a switch box on the wall containing two single-pole switches (one for the lights and one for the fan). The neutral is not carried down to the switch box. Everything works great with the exception of the problem described below.
When the switch is in the closed position, I get a voltage reading of 120-volts (reading both to neutral and ground from the "hot") - which is what I expect. However, when the switch is in the open position I get a reading of about 30 volts (reading both to neutral and ground from the "hot") - which I do NOT expect. Can anyone lend some wisdom here as I am a bit stumped.
As I type this it occurs to me that the switch might be bad and that I should check this before proceeding much further. It is a brand new switch but Occam's Razor tells me to start there.
L

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• posted on June 26, 2003, 9:20 pm
John, I appreciate the speedy response. When I measured, the only load on the circuit were 6 recessed lighting fixtures. I was measuring from the "hot" of the circuit to the neutral of the same circuit and I was reading 30 volts at that point. However, I did not try to measure with no load whatsoever on the circuit - I will try that tonight (as well as looking at the switch). I have just never seen voltage that high between the neutral and the voltage side of an "open" circuit.
Thanks again for your time . . .
L

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• posted on June 26, 2003, 9:50 pm

"hot" with the switch controlling it off? Otherwise you should have gotten 120v. If you are actually measuring across the load with the switch off then I don't understand it either. The load should short the inputs to the meter with some resistive load. However if you were measuring from the open switch side to some convienient neutral then I would suspect that you are getting voltages due to noise and or line load induced voltages caused by long runs and powered equipment on line.

Neither have I. Try putting a resistive load across the 30 v. My guess is it is going to drop to virturally nothing.
Regards,
John

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• posted on June 27, 2003, 7:44 am
Maybe the sub panal ain't grounded right

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is it