Voltmeter measuring 55 volts at switch?


Old 05-08-08, 03:32 PM
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Voltmeter measuring 55 volts at switch?

I have an overhead hallway light in my house. Two switches control this light; for a few weeks, one of the switches has stopped working. Today I took the light down to make sure there was no arcing going on in the ceiling. I then used a voltmeter to try and test the "broken" switch - fully open, it only shows 55 volts, closed it shows nothing... so it seems that the switch is working, but for some reason is only carrying 55 volts (suspiciously close to 1/2 of 110). For the hell of it, I tested the other switch that has been working, and it is also only carrying 55 volts. Is this normal for multiple switches controlling one light, or should I be concerned about something happening in the walls to cause resistance such that the voltage is dropping by half?
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Old 05-08-08, 03:47 PM
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You're measuring an effect called phantom voltage. Use a plain neon-bulb tester and you will see there is actually no power.

Regarding the switch that stopped working: was it always on, always off, didn't toggle? Did anything recently change on the circuit?
Old 05-08-08, 03:51 PM
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if you are using the digtial meter they can read "ghost voltage" i always go at least two ways

use the neon test light

use the anglog meter [ non digtial type ]

that two most common way because i can able load it up a little to bleed off the ghost voltage.

for the switch one trick i do all the time to elamted the odd voltage is remove the light bulb[s] in the luminaire that way i can elemated the mistery voltage.

but when you replace the switch espcally with the 3 way's you have make sure you note what screw is a common screw useally marked either dark colour screw or " common "

that is most impoart part for other two wires it don't make the diffrence there due they are only traveller.

Old 05-08-08, 03:58 PM
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Thanks everyone for the replies; the switch that was bad had to be always on in order for the other switch to work. I just replaced it and am now measuring 110 at each switch, and everything is working properly! Thanks for clearing me up on the ghost voltage - had not heard of that (was borrowing a neighbor's voltmeter, and he was the one who suggested there could be a short in the walls causing the voltage drop).

I will probably be posting again shortly, as I am now going to be replacing the light that I took down (my wife has hated it for years and I figured I might as well while I've got everything apart).
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