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Old 03-05-2011, 08:35 AM   #1
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Pen tester false-positive?

I was rewiring a wall switch to vanity light in my bathroom to remediate a code violation. Previous wiring (code violation) as follows: 12-2 wire going from switch to buried junction box where it was spliced to new 12-2 wire which went to the light. New wiring I connected goes directly from wall switch to light (no buried box). Just for giggles before closing everything up, I voltage pen tested the "discontinued" wire and the meter continuously beeped when I turn the newly wired switch on AND the adjacent but separate wall switch for the bathroom fan on. If one or the other were on, the pen tester didn't sense anything. It also did not sense anything if I touched the wire 12-2 wire insulation with my other hand while pen testing. I know for a fact that this wire was disconnected on both sides of the buried junction box. How is the pen tester getting current and why when only with both switches on? Is it static from the other lines/operating fan? I did not have a meter tester so I hooked up a light to it and whatever voltage there was could not power the light. So i taped it, labeled it discontinued, wire nutted them, and left them in the wall. Is this ok?


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Old 03-05-2011, 11:37 PM   #2
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pen testers are dangerous if not well understood. I do not recommend them for troubleshooting at all.(they aren't a troubleshooting tool). They do one thing only: Is there power? they are unable to reliably answer the question: Is it dead?


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Please follow the code - its there for your safety no matter how inconvenient.
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Old 03-06-2011, 07:38 AM   #3
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I appreciate your reply. I have gathered as much about pen testers after doing some additional research. Wish I would have ran out and got a multimeter before closing everything up. I'm 99.9% sure everything is safe, just perplexed by the situation and wondering if anyone could provide reassurance or specific explanation.

Both ends of the line were cut from power/devices and would only set the pen tester off when many other devices were on in the area. As I said before, the pen tester would turn off when I touched the dead line with my other hand. It would not power a 3 light vanity hookup either so I am going to leave it as is. Just kind of thinking out loud here. Thanks!
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Old 03-06-2011, 11:11 AM   #4
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Homeowners benefit more from solenoid testers. Multimeter's for DIY'ers serve only to confuse.
By one of these. Cheap, reliable and indestructible.
No contact testers can cause serious injury and or death if used improperly or used by the uninformed.
This tester has a solenoid inside it. When the probes come in contact with power the solenoid shifts making a distinct noise and has a distinct feel.
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bury dead wires , pen tester , voltage tester

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