Why the weird glow?

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  #1  
Old 01-06-16, 09:15 AM
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Why the weird glow?

I wired my garage for 30 florescent fixtures on five 15 amp circuits. Each home run of the 5 circuits goes to one switch. Two circuits are on three-ways with the black and white wires travelers to the second switch and the red to the COM terminal of the second switch and to the black from the lights.

I am going to insulate the attic before I install the lights so I have been checking the wiring with a voltage detector taped to a pole. It glows brighter the closer I get to the HOT wire. But why to a get a glow when I get near the black wires even with the switches "off"? And brighter (normal) when the switch is "on"? The other wires on the single-pole switches have no glow when the switch is "off".

I have checked with my Gardner Bender Circuit Alert and it flashes and beeps only when the switches are "on".
 
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Old 01-06-16, 09:47 AM
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A non contact tester is/was only designed to inform you that a hazardous voltage is in the area. It picks up voltages inductively that travel between live and dead wires. You cannot use it to make any meaningful tests. You should pre-test your circuits with a light bulb in a socket with two wires or a voltage tester.
 
  #3  
Old 01-06-16, 03:05 PM
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Is there another way? It is not feasible to get up a ladder to boxes. Why does the non-contact tester act that way?
 
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Old 01-06-16, 03:41 PM
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A non contact tester does not detect voltage despite what it may say on its packaging. It detects electromagnetic fields. Any electromagnetic field can set it off. A lot of things can create electromagnetic field.
 
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Old 01-06-16, 06:03 PM
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Any other testing methods? Any reason to think something is wired wrong?
 
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Old 01-06-16, 06:09 PM
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If it works, there is no smoke, and the breaker doesn't trip it is okay. Those are the best tests.
 
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