Non-contact voltage tester?

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Old 01-23-18, 01:44 PM
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Non-contact voltage tester?

i have a new Non-contact voltage tester, Garden Bender GVD-3504, that i used at a friends house and it did not indicate any live circuits but we plugged lights in and they worked. Upon returning home i checked 20+ outlets in my home and the tester worked as described. It is supposed to detect circuits between and 50-600 VAC. A friend suggested that the first house's power was below 120 volts. Any thoughts on why there might not be any readings at the first house?
 
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Old 01-23-18, 01:51 PM
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Many consider non-contact testers to be toys instead of tools.
 
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Old 01-23-18, 02:35 PM
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Did you confirm the voltage with a multimeter at either residence? If you get a unexpected response from a NCVD, always follow up with a multimeter to get a true reading.
 
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Old 01-23-18, 02:42 PM
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If you are going to rely on a NCVD, I would recommend a higher quality one similar to the one below.
 
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Old 01-23-18, 02:43 PM
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i have a new Non-contact voltage tester, Garden Bender GVD-3504, that i used at a friends house and it did not indicate any live circuits but we plugged lights in and they worked.
How did you test it?
Usually that type of non-contact tester requires the probe to be right next to the live wire. Some outlets have contact point deeper than the other and some probes may not be detect live wire.

Also, you must test your non-contact tester to a known live wire before use in case of false negative (which usually is broken tester or out of battery).

I use non contact tester a lot, but I only use it in following way to be safe.
1. Put the tester next to the wire you will be working on and confirm it is live.
2. Turn off breakers one by one (or educated guess) until your non contact tester stops beeping.

This way you know for sure that the tester was working properly you actually turned off the correct circuit.

Non contact test should never be used to test if you actually have 120V at the circuit, cause it will detect much lower voltages as live.
Also, if there is a wire running next to the live wire and the wire is not connected to ground (or neutral), it will also give false positive reading due to induced voltage on the line. This is also sometimes called phantom voltage. (Digital multimeter will give false reading in this case as well)
 
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Old 01-23-18, 02:50 PM
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Since many testers require you to be _really_ close to the conductor, if the house had tamper-resistant receptacles there's almost no way to get close enough to the contacts without resorting to other means.
 
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Old 01-24-18, 01:13 AM
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Thanks

Thanks for everyone's input. I am returning to my friends house in a couple of days with a regular multimeter to check the circuits. This was my first time using a non contact tester.
 
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Old 01-24-18, 05:46 AM
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Analog multimeters are less likely to give confusing results than digital.
 
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