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bamadad33 02-04-2011 08:02 PM

single pole light switch
On bedroom light switch only getting 30 volts from white wire pole to black wire pole with light switch in off position, is switch bad or what?

Jackofall1 02-04-2011 08:13 PM

Sounds like you have a bad connection upstream of the switch, or right in the box that the switch is mounted in.


My bad, I didn't read the post correctly, trying the measure voltage across a switch will show you nothing, try measuring the hot terminal to ground if you want to see if there is voltage at the switch.

AllanJ 02-04-2011 08:14 PM

Does the light not work? Is the lamp (bulb) good?

Measuring across the two terminals of a switch generally does not give useful information. You should get "nothing" (0 volts) for the switch in the on position and usually you get "something" (anything) for the switch in the off position. But if the switch controls just a receptacle and nothing was plugged in or turned on, you get "nothing" all the time.

One wire to the switch is unswitched or raw power. You should measure 120 volts between it and neutral, although you might have to stretch a wire from a neutral elsewhere on that circuit across the floor over to this switch box. The other wire to the switch should measure 120 volts to neutral when the switch is on and zero volts to neutral when the switch is off. If a white wire is attached to the switch, it should be the unswitched hot.

joed 02-04-2011 08:19 PM

Does the switch work? What are you trying to determine by measuring across the switch?

kbsparky 02-04-2011 08:59 PM

Measuring across a switch that is "off" should result in a reading of 120 Volts. A reading of 30 volts indicates either a bad connection in the light, or a burned out bulb.

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