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Three-way switches allow current on "off" traveler, hot ground.

Three-way switches allow current on "off" traveler, hot ground.

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  #1  
Old 12-14-11, 06:31 PM
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Three-way switches allow current on "off" traveler, hot ground.

Hello! I am new to the forum, but have worked with several wiring projects at home. I have a three way light circuit with multiple problems.

I looked into this because someone received an electrical shock while working with the light fixture. The circuit has the following configuration:

1. Three way light switches are installed. I have removed both and checked continuity. They function normally.
2. Power is fed to a junction box that has an outlet (always on - garage door opener).
3. Two garage lights wired in parallel go in one direction from the box.
4. A cable runs to a second junction box. A cable connects a third garage light to the circuit. Another cable runs to a switch that operates the attic lights, provided the three way switches are on.

Problems: The first light in step 3 burns out more often than any of the others -- about once every couple of weeks. I found that a voltmeter between the ground conductors of the first and second lights in step 3 showed about 5 volts of electricity, regardless of the light being on or off.

A voltmeter between the hot & neutral and hot & ground of the first light in step 3 showed 5 volts when the light was switched off.

I traced the wires back to the junction box in step 2 and found removing one of the switches from the circuit (wiring one of the travelers in as a switched wire), kept the voltage out of the light fixture when the switch was off. When I put my voltmeter between the traveler (that was not used) and the ground, however, when the light was switched on, the needle moved about 1/4 of the way to maximum -- regardless of what scale my meter was set to. The meter works properly otherwise.

Questions: Why does my needle move the same amount regardless of scale? Where might the current in the grounding conductor be coming from? What more information do you need?

Thanks for wading through this. I know it's a lot.
 
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Old 12-14-11, 06:49 PM
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I found that a voltmeter between the ground conductors of the first and second lights in step 3 showed about 5 volts of electricity, regardless of the light being on or off
Usually a false reading from a cheap digital meter. It is cause by meaningless induced voltages that aren't canceled out because of the high impedance of the meter. An analog meter would probably show 0v.
 
  #3  
Old 12-14-11, 06:52 PM
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Thank you for you comment. The meter I am using is cheap, but analog. The ground conductors do arc when they are connected. As do the hot and neutral conductors as they are touched to the terminals of the light fixture.
 
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Old 12-14-11, 07:03 PM
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Hot and neutral conductors will arc if there is a load on the circuit and a connection is made or broken.

You should not be making connections with the power on.
 
  #5  
Old 12-14-11, 07:24 PM
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The arcs occurred when the light was switched off -- after that I shut off the circuit breaker
 
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