Non-Contact Voltage Detector -- less than 100% effective

[drcampbell]

Actually I have found they deliver false positives too.

A false positive won't kill you.

Or rubber soled footwear?

Many rubber compounds (and plastics and other polymers) are conductive. Tires, for example. They're deliberately made conductive so that any static charge on the vehicle drains away when you pull into a filling station. And even if they are "non-conductive", they still might provide enough capacitive coupling to hurt you. Unless they're listed and have a maximum voltage rating, don't rely on your soles saving you.

 

[jaggedben]

A false positive won't kill you.

Unlees it's the only detector you have and you stop using it because it cried wolf then you stop testing at all. Or you get yourself into a situation where you're convinced something must be off and the tester must be giving a false positive like it so often does, so you cut the cable anyway.

I mean, ok, the false positive won't kill me because I basically stopped using mine when I realized it was trash, and I have DMMs. But I worry a bit about DIYers and noobs who don't get good training.

 

[LarryFine]

I'll use a non-contact detector to verify on and off while operating a breaker, but if I need to make real contact with wiring, I will check it again with my solenoid tester, not a voltmeter.

 

[micabay]

I have found there are two things that improve the reliability of these things greatly:

1. Only use a fluke, throw any others in the garbage immediately.

2. Keep/make sure the batteries are good.

Agreed. I haven't found one that is a non-fluke brand that I like or trust. These are great for putting on the line wire into a dishwasher, and running to shut the breaker off. You know you have the right breaker when you can make the loud BEEEEEEEEEEEEEEEEEP disappear and re appear via the breaker.

 

[ptonsparky]

Agreed. I haven't found one that is a non-fluke brand that I like or trust. These are great for putting on the line wire into a dishwasher, and running to shut the breaker off. You know you have the right breaker when you can make the loud BEEEEEEEEEEEEEEEEEP disappear and re appear via the breaker.

I didn't like the Flukes because of their narrow range.
A local wholesaler sells 'Ultimate AC Sensor Model 3000' They put their own distributed by label on it.

It also says "WARNING" "TEST BEFORE USING"

 

[garbo]

A false positive won't kill you.



Many rubber compounds (and plastics and other polymers) are conductive. Tires, for example. They're deliberately made conductive so that any static charge on the vehicle drains away when you pull into a filling station. And even if they are "non-conductive", they still might provide enough capacitive coupling to hurt you. Unless they're listed and have a maximum voltage rating, don't rely on your soles saving you.

Have at least four of these non contact testers but still like to use one of my Ideal Voltron tester. They have batteries that I always touch together to make sure test leads & tester is working. Some times break out my Fluke meter to check if circuit is energized. Had the non contact testers give me false power on in long runs of conduit with several different energized circuits. One case they had a 8 by 8" through over 150' long with at least 8 different circuits each of 480 volts, 240 volts & 120/208 circuits all of which were on 20 amp breakers.

 

[readydave8]

I've been throwing away NCV testers for years, unless there was someone I was mad at, then might give him one

But been using one recently, not so much to tell if circuit dead but more often to confirm which wire or cable is which, on-off-on

 

[readydave8]

By the way I like thread title, "less than 100%" reliable

Yeah sometimes I can educated guess better

 

[readydave8]

Do I have to be holding NCVT for it to work? No

Laying on wooden workbench, visegrips holding button, still works

Thanks @hornetd

 

[mtnelect]

In my apprenticeship I worked with a journeyman in the "High Desert" that would wet his fingers to test residential wiring. At the end of the day, he would always invite me to the "Moon Lighter", never took him up on it.

 

[ptonsparky]

In my apprenticeship I worked with a journeyman in the "High Desert" that would wet his fingers to test residential wiring. At the end of the day, he would always invite me to the "Moon Lighter", never took him up on it.

Yes, some of the guys at the first shop I worked for used their fingers too. Calloused work hardened hands and a dry floor.

 

[ActionDave]

This hasn't come up on the forum in a while. Kickin' it old school...

AMERICAN ELECTRICIANS’ HANDBOOK
7th Edition 1953 McGraw-Hill
MEASURING, TESTING, AND INSTRUMENTS

154. Electricians often test circuits for the presence of voltage by touching the conductors with the fingers. This method is safe where the voltage does not exceed 250 and is often very convenient for locating a blown-out fuse or for ascertaining whether or not a circuit is alive. Some men can endure the electric shock that results without discomfort whereas others cannot. Therefore, the method is not feasible in some cases. Which are the outside wires and which is the neutral wire of a 115/230-volt, three-wire system can be determined in this way by noting the intensity of the shock that results by touching different pairs of wires with fingers. Use the method with caution and be certain that the voltage of the circuit does not exceed 250 before touching the conductors. (This and several paragraphs that follow are taken from Electrical Engineering).

155. The presence of low voltages can be determined by tasting. The method is feasible only where the pressure is but a few volts and hence is used only in bell and signal work. Where the voltage is very low, the bared ends of the conductors constituting the two sides of the circuit are held a short distance apart on the tongue. If voltage is present a peculiar mildly burning sensation result, which will never be forgotten after one has experienced it. The taste is due to the electrolytic decomposition of the liquids on the tongue which produces a salt having a taste. With voltages of 4 or 5 volts, due to as many cells of a battery, it is best to test for the presence of voltage by holding one of the bared conductors in the hand and touching the other to the tongue. Where a terminal of the battery is grounded, often a taste can be detected by standing on moist ground and touching a conductor from the other battery terminal to the tongue. Care should be exercised to prevent the two conductor ends from touching each other at the tongue, for if they do a spark can result that may burn.

 

[Little Bill]

I didn't like the Flukes because of their narrow range.
A local wholesaler sells 'Ultimate AC Sensor Model 3000' They put their own distributed by label on it.

It also says "WARNING" "TEST BEFORE USING"

That sounds like a Santronic. It's the best of that type that I've found. No button to hold down. I've tested it along side several brands and it beats all the others I've tried hands down. My supply house also sells them branded with their name. I do have a Fluke that is pretty consistent but has no "beep", which I use often. I can place the Santronic on a hot wire and walk away and listen for the beep, or absense of a beep.

 

[EeeeVeee]

That sounds like a Santronic. It's the best of that type that I've found. No button to hold down. I've tested it along side several brands and it beats all the others I've tried hands down. My supply house also sells them branded with their name. I do have a Fluke that is pretty consistent but has no "beep", which I use often. I can place the Santronic on a hot wire and walk away and listen for the beep, or absense of a beep.

The Fluke 1AC II has a button to turn it on, then you see it flash every second or so to know that it’s on, and it has a beeping sound as well as the light staying on solid when it detects voltage.

I’ve been using this model for well over 15 years and it has been excellent. Sometimes I will get false positives due to ghost voltage, but never a false negative.

I use this to identify breakers with the beeping sound just like you said.

 

[jim dungar]

That sounds like a Santronic. It's the best of that type that I've found. No button to hold down. I've tested it along side several brands and it beats all the others I've tried hands down. My supply house also sells them branded with their name. I do have a Fluke that is pretty consistent but has no "beep", which I use often. I can place the Santronic on a hot wire and walk away and listen for the beep, or absense of a beep.

We got this brand from our NFPA70E safety team. They said it was the only one approved by OSHA. It had something to do with not needing a ground so they worked when wearing voltage rated gloves.

 

[don_resqcapt19]

I didn't like the Flukes because of their narrow range.
A local wholesaler sells 'Ultimate AC Sensor Model 3000' They put their own distributed by label on it.

It also says "WARNING" "TEST BEFORE USING"

That is one of the issues as you can't really do that...the conditions at the test location will not be exactly identical to the conditions at the location where you are trying to test for voltage. Totally different from a meter with two leads.

 

[ptonsparky]

That is one of the issues as you can't really do that...the conditions at the test location will not be exactly identical to the conditions at the location where you are trying to test for voltage. Totally different from a meter with two leads.

At least you'll know the battery isn't dead.

 

[Bill_F]

Never fully understood about the NCVT operational principle. Awesome thoughts here, esp the insulated, up on fiberglass ladder thoughts.
I'm sure everyone knows about the Klein old NCVT model # 1 recall.
Thanks folks!!!
Bill....

Non-Contact Voltage Testers Recalled by Klein Tools Due to Shock Hazard

Consumers should immediately stop using the recalled non-contact voltage testers and contact Klein Tools for instructions on receiving a free replacement tool.

www.cpsc.gov

 

[electrofelon]

I'm sure everyone knows about the Klein old NCVT model # 1 recall.
Thanks folks!!!
Bill....

Non-Contact Voltage Testers Recalled by Klein Tools Due to Shock Hazard

Consumers should immediately stop using the recalled non-contact voltage testers and contact Klein Tools for instructions on receiving a free replacement tool.

www.cpsc.gov

See post #12, throw any non-fluke voltage detector in the garbage!

 

[Bill_F]

Ha!
Thanks.