Non-contact voltage testers are a must for home wiring

Originally published at: Non-contact voltage testers are a must for home wiring | Boing Boing

as any electrician will tell you, these are often wrong. Get a meter and learn how to use it before poking around in an electrical box.

13 Likes

Per the Amazon reviews, it often doesn’t work and can give a dangerous false negative.

5 Likes

I returned mine. It kept giving false positives when there was another live circuit anywhere nearby. That’s about as bad, since after a while one starts to disregard any warnings.

1 Like

Stay out of electrical boxes unless you are either A. a professional, or B. been shown how to poke around electrical boxes many times by a professional.

Not worth it.

3 Likes

I turn off the main before doing any home electrical work. My father-in-law happened to be over when I was replacing some outlets with gfci on a bathroom I’m installing. He told me I’m being overly cautious, and that flipping the breaker is enough. He then sheepishly admitted he’s also been zapped a couple times when he thought he flipped the breaker and hadn’t.

4 Likes

My preferred method

4 Likes

I’m pretty handy with electrical, and I turn breakers off and put electrical tape over the switches. And I’ve still been zapped.

4 Likes

There’s lots of helpful DIY videos on YouTube.

8 Likes

That guy is great. There’s a guy out there who posts TikToks, or maybe Instagrams?, of his perfectly-wired subpanels. They’re truly artistic. Wish I could find them.

1 Like

Everything I know about electricity I’ve learned from Electroboom and BigClive.

I probably shouldn’t be allowed near anything with a power source.

8 Likes

I didn’t realize these things were faulty. I use it routinely and while it is a little bit finicky, it has done a good job showing me when there is something live. I don’t think I’ve ever seen a false negative. But based on these post comments, I think I will move to a different solution

2 Likes

I’m sure this was just a slip of the keyboard, but voltage detectors do not detect current. They detect voltage.

There are non-contact current meters, but those serve a different function.

1 Like

My house has rooms with multiple circuits and also some dual-gang boxes with multiple circuits. Some 60 Hz tickles will teach you the value of testing every wire in the box.

6 Likes

I’ve used them to quickly test for “dangerous”, not to test for “safe”. “Safe” is confirmed by a real multimeter.

5 Likes

If you’re going to work on an outlet, besides the noncontact tester and voltmeter there are also outlet testers. Risk-averse people (like me) will use all three:
image

Testing with a meter or other device with mechanical connection has the danger that the contacts in the outlet are bent or broken so that your probes somehow don’t touch them. Using the wireless tester as well adds a layer of safety. All these devices (noncontact tester, voltmeter, outlet tester) are so small and inexpensive that there is no downside to having all three. (Inexpensive if you don’t use a precision meter like a Fluke or similar to test your outlet. I saw an Adam Savage video where he recommended exactly this, which I found puzzling. Mains power is dangerous for meters too, testing voltage is the perfect job for a $5 meter.)

4 Likes

While fixing some of the previous owners “improvements” in my house I actually found a single gang box with hots from two circuits in it… (but only one neutral which was awesome of them). I agree, assume nothing, test everything…

(Also fun is when you discover inductance/capacitance coupled circuits …)

PS on the thread topic I prefer the dual range non contact Klein testers. It’s nice to split low and high voltage in some situations…

2 Likes

I have what is basically a neon bulb with two probes on it, and it’s served me well. Also have a meter in case of doubt.

1 Like

Or a switch-off-and-lock-out procedure :smiley:

3 Likes

Non-contact voltage detectors work fine if used properly. I have never seen a professional electrician use a multimeter to test whether a circuit was live. They use these. Mine is a Greenlee but Klein makes decent enough tools. I have no experience with this particular one.

@BradC : It’s not unusual to have two hots in one junction box, and sharing a neutral is fine as long as it’s not overloaded. That’s not to say how that box was wired was correct, of course!

I just looked at some of the Amazon reviews, and at least some of them are exactly what you’d expect from the general public using specialized tools. That is to say, the tool is fine, the user is not using it correctly. It’s still possible this isn’t a great voltage detector but I would not use the Amazon reviews as an indictment of it.

1 Like