Can Non Contact Voltage Detectors be trusted?

[frankiee]

We have been using Non Contact Voltage Detector
I like it because one hand operation and dont have to take eyes off what I am holding it to and see the red light, if it lights. Also I like it because dont have to worry if the ground is good for it to function. Also, I can give a quick check of the bulb by touching my shirt to see if it turns red.
Everything seems so perfect. IS it?
All I want to know is are these Non Contact Voltage Detectors reliable?
Some times I wonder
Been using a voltmeter long enough that I trust it
I think the Non Contact Probe works by capacitance.
Thank you for anybodys input.

 

[Skogsgurra]

I would not trust it on DC. Or rather - I would not trust it at all if there are any DC installations in the building. Always check voltage with a reliable instrument before working on a circuit. Short and ground is also a good practice. Will keep you from being burnt if someone swithes power back on - which happens more often than we like to think.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[dpc]

They don't work on dc. I wouldn't trust my life to one even on an ac circuit.

Standard procedure should be to test first with non-contact probe - if it lights up, you know it's hot. If it doesn't, it MIGHT be dead. At that point, you can test with contact voltage probe specifically designed for voltage testing. DMMs are not recommended for voltage testing. A dedicated voltage tester is less likely to fail, or to be used on the wrong setting, or with leads in the wrong holes.

(I know - do as I say, not as I do....)

 

[ScottyUK]

Prove your tester before you use it, then prove it still works after you have tested. Otherwise... are you really sure it is dead?


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Sometimes I only open my mouth to swap feet...

 

[resqcapt19]

There are cases when using this type of tester to test for power on cables or cords with paper fillers, where if the paper is wet, the tester will no power when in fact the power is on.
Don

 

[ScottyUK]

That's interesting - hadn't heard that before. Something to be aware of if working in old buildings.


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Sometimes I only open my mouth to swap feet...

 

[powerjunx]

frankee, we've using such device on our 13.8KV switchgears only after the system were shutdown, as well as when our metering instrument depicts abscence of power, and a physical draw out of Power CBs were carried out. These actions were just few of our routines.
I hight restrict not to use such device when the system is live. We have cases of flash over, and mishandle.

 

[ruggedscot]

Sorry non contact voltage detectors on 13.8kV.......

HV is specialised and only the right gear should be used on this sort of system - Home Depot 9.99 non contact testers are not the type of testers you want to be using on 13.8. Believe me ! Next you will be looking for a 13.8kV lamp to make up a set of test lamps.

Rugged

 

[Hewlett]

I trust it to the degree of comforting myself on small/ low energy jobs where I don't physichally come in contact with conductors. As example, when needing to do retightening on a lot of (100's) small screwterminals I always "brush over" with such a device to quickly discover if there was something the main breaker did not kill, or if I'm in the wrong box (which have happened).
I most definately do not rely on this if I need to "handle" the wiring, or work on high energy circuits.

 

[eddykurent]

Non contact detectors are accidents waiting to happen. I believe in a domestic enviroment they may have some value to the DIY industry

 

[HCBFlash]

resqcapt19 said;

"when using this type of tester to test for power on cables or cords with paper fillers, where if the paper is wet, the tester will no power when in fact the power is on."

That's worth hearing Don, that explains, or confirms some of my own experiences!

I use one made by Fluke all the time. I've used others, and some have some other/nicer features than the Fluke,,, BUT as mentioned above and in every electrical safety class and text, as well as service, troubleshooting, instrumentation, etc.: ONLY use a tester you trust because it has been tested and proven. They are only intended for a cursory check, and are simply a fairly good indicator.

 

[AlwaysConfused]

Hi, i agree with Hewlett, i never ever rely on them for disconnections. I think their main purpose is to let you know that that's power there, so you don't have to get into a terminal box, cabinet etc.. saves time. I only use them in fault finding if I want to know a supply is switching when it should etc.. and if it showed up an error, then out comes the voltage tester. Also I have had experience with them not working through screened cable.