Use of non-contact voltage detector for verifying no voltage present

[don_resqcapt19]

...
It is imperative that the testing device be checked by testing on a known energized voltage source first, then checking the circuit in question, and then verifying that your testing device is working against a known energized voltage source. I have a fluke non contact tester and I. Never trust it to be working unless I test it by checking a know energized voltage source. ...

That is not a valid test when using non-contact voltage tester, unless all of the conditions between the know live source and the source being tested are exactly the same. It would be very rare where the conditions would be exactly the same. Sure it does prove that the tester works on the know source, but does not prove that the test source is not live as the differing conditions may give a false negative on the source being tested. Other types of testers do not have the same condition issues as the non-contact testers do.

 

[templdl]

That is not a valid test when using non-contact voltage tester, unless all of the conditions between the know live source and the source being tested are exactly the same. It would be very rare where the conditions would be exactly the same. Sure it does prove that the tester works on the know source, but does not prove that the test source is not live as the differing conditions may give a false negative on the source being tested. Other types of testers do not have the same condition issues as the non-contact testers do.

I see you point Don and as such would there be a valid test for a non-contact device?

 

[don_resqcapt19]

I see you point Don and as such would there be a valid test for a non-contact device?

In my opinion, no. That being said, I have used them for the purpose being discussed. As you stated before, you need to have a very good understanding of how they work and the conditions that can give a false negative.

However the information from Klein and Ideal, in my opinion, tells you that you can't really use them for the purpose of proving the circuit is safe to work on. The information from Fluke stops short of that, but all three use the same principle to detect voltage.

 

[templdl]

In my opinion, no. That being said, I have used them for the purpose being discussed. As you stated before, you need to have a very good understanding of how they work and the conditions that can give a false negative.

However the information from Klein and Ideal, in my opinion, tells you that you can't really use them for the purpose of proving the circuit is safe to work on. The information from Fluke stops short of that, but all three use the same principle to detect voltage.

Then, before using such a non-contact device that they should be used only if you recognize that they sould not be used carelessly and to be a trusted device in of by themselves but in addition or a supplement to other trusted testing devices.

 

[don_resqcapt19]

Then, before using such a non-contact device that they should be used only if you recognize that they sould not be used carelessly and to be a trusted device in of by themselves but in addition or a supplement to other trusted testing devices.

If you have to use another tester to be safe, why not just use the second one and skip the non-contact one?

 

[GoldDigger]

If you have to use another tester to be safe, why not just use the second one and skip the non-contact one?

To reduce the chance of getting injured when using the contact tester, of course.

 

[PetrosA]

In my opinion, no. That being said, I have used them for the purpose being discussed. As you stated before, you need to have a very good understanding of how they work and the conditions that can give a false negative.

However the information from Klein and Ideal, in my opinion, tells you that you can't really use them for the purpose of proving the circuit is safe to work on. The information from Fluke stops short of that, but all three use the same principle to detect voltage.

Thanks for tracking down those instructions. Somehow it doesn't surprise me that not all manufacturers or sellers of non-contact testers have a decent level of confidence in their product. I've tried a few brands and nothing has performed as well as the Flukes I've owned. It is by far the most predictable tester of any I've tried. Now, whether I'd trust my life to it... Maybe. I will certainly trust it enough to use my $14 wire strippers to cut a cable it says is dead, but not my $40 Knipex linemans

In most cases it is enough to get me past "reasonable doubt" at work - IOW, I know that a switch, breaker or GFI is off or tripped, and the tester has confirmed my knowledge/assumption of both states.

 

[Wirenuts951]

Just a quick question,

Does a "non-contact" voltage detector qualify as the final test for "no-voltage" prior to working on, hopefully, de-energized parts in equipment which has been locked/tagged?

thanks!

Lock, tag and try. I use my non contact voltage detector on a daily basis and it has never failed me, but that doesn't mean it won't. I always do both just to be sure.

 

[sparkcontrol]

always use a contact tester.....never trust a proximity tester

 

[brother]

Also look at the minimum voltage that the testers will detect. NFPA 70E-2012 (110.8(B) & elsewhere) considers anything above 50V to be hazardous. Many of the Fluke models are rated to detect 90-1000V, or they offer a 20-90V model. How many folks use both the 90-1000V model only and may be missing voltages in the 50-90V range?

I've actually mentioned this same issue with other workers. I have witnessed where a lineman was working on a house service that was disconnected and he touch the conduit and got shocked, twice even! After investigation, we found that the communication and cable lines had voltage coming in that was around 70 -80 volts. The fluke 90-1000v non contact tester would have picked this up.

I at least use non contact testers that start at 50volts and then up. I do not use the fluke non contact testers, but I do use and like their digital meters.

 

[kwired]

I've actually mentioned this same issue with other workers. I have witnessed where a lineman was working on a house service that was disconnected and he touch the conduit and got shocked, twice even! After investigation, we found that the communication and cable lines had voltage coming in that was around 70 -80 volts. The fluke 90-1000v non contact tester would have picked this up.

I at least use non contact testers that start at 50volts and then up. I do not use the fluke non contact testers, but I do use and like their digital meters.

If it was from telephone it was likely DC. I'm guessing a non contact tester may not pick up DC voltage, based on the capacitive coupling concept behind their method of operation, unless you were lucky enough to be testing for the short time while the "capacitor" is charging.