Constant Current In A Light Fixture Even When Off - Electrical - DIY Chatroom Home Improvement Forum

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Old 11-20-2012, 01:01 AM   #1
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Constant current in a light fixture even when off


I had replaced a 3 way switched ceiling light fixture a couple of years ago and today while I was changing the light bulbs I was checking the current with my multimeter. I noticed that even when turned off there's a constant AC current of 21 volts. Turned on it's about 121 volts. So is it normal for a light fixture to have constant 21 volts going through it? If not should I then take a look at the wiring again? I'm very much worried that I'm wasting electricity. Wondering if these are reasons my electrical bill are so high all the time and do I need to check everything I worked on previously.

Thanks for your advice,


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Old 11-20-2012, 07:25 AM   #2
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Constant current in a light fixture even when off

1. Does the light switch controlling that fixture have a tiny light inside? The switch light is kept lit by a minute current flowing through the light being controlled.

2. You could be reading phantom voltage (minute voltage induced by live wires juxtaposed with the dead circuit wires you are making measurements on over a long distance) in which case if you connected a small incandescent light across the two meter probes at the same time you are making your measurement, the voltage will drop to zero.

Most non-digital voltmeters are not sensitive enough to measure such phantom voltage.

Cumulative current resulting from phantom voltage all through the house could add up to a couple of watts.


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Last edited by AllanJ; 11-20-2012 at 07:43 AM.
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