Crazy lighting voltages


  #1  
Old 04-08-03, 11:01 PM
mwatt
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Question Crazy lighting voltages

The lights in my kitchen went dim then after a few days wouldn't come on at all. That includes 4 flourescents and 5 recessed spots. (The hall lights are on the same circuit and they work fine.)

I opened up the overhead flourescent fixture and checked the voltages at the box - weird! For example...

white- black: 70V
white-ground: 115V
black-ground: 20V

Similar weirdness at the wall switches - 30V to 75V. I've done a fair amount of DIY electrical stuff over the years, but this is beyond my understanding. I would appreciate any clue.

Alan
 
  #2  
Old 04-09-03, 05:19 AM
J
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You have an open neutral somewhere in that circuit. Check all the connection in the boxes. If you know the route the cable takes the problem is in the last working box or the first box with the bad voltages.
 
  #3  
Old 04-09-03, 07:31 AM
J
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Those strange voltages are called "phantom voltages". They are caused by taking voltage readings with a high-impedence digital multimeter to a wire that is an open circuit. You should treat these voltages as if they were zero, which they would be if you had taken the readings with an analog multimeter. Almost everybody goes for the digital multimeters these days because they are way more cool. But most people would be better off with an analog multimeter.

The white-to-ground readings of full voltage are due to the fact that the white wire is getting voltage through something that is plugged in.

All of this is just a long way of saying that Joe is correct. You have an open circuit on a white wire somewhere on this circuit. Worst case is that you'll need to look in every box on this circuit to find it.

Failed backstab connections in receptacles are often the culprit.
 
 

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