Energized Panel But Confused

Hey everyone, hope your all doing ok.
I came across something that I found puzzling and I’m still learning so looking for some clarity.

I inspected a single family house built late 50’s / early 60’s and one of the first things I do when I get to the main service panel is do a quick test with my non contact tester just to make sure that the whole panel is not energized. This one happens to show that it is as the light went on and the beeping sound went off. So I decided to note this and not inspect further.
However, the agent (pre-listing inspection - seller agent) touched the door and the panel (for whatever reason) and nothing happened. He was not wearing gloves or anything.

Was my tester incorrect or is there something I’m missing as I don’t understand. Here are some photos.
Appreciate any feedback. Looking to learn.

I’m sure so better experts will chime in shortly. The non contact testers show the possibility of a voltage based on the emf of house wiring. So sometimes they give erroneous readings. That said if it goes off, stop, and kick it to an electrician to diagnose. To get a shock from an energized cabinet you need to be grounded. In the right circumstances a person might touch a cabinet with stray voltage on it with one hand and rubber soled shoes and not feel anything.


False readings with non-contact voltage “detectors” are common.

Search the web for the facts and science. Stray voltage, induced voltage, and non-grounded circuits can cause that condition, amongst many others.

I’ve owned some that trigger an alarm from across the room, and others that won’t trigger while touching a live conductor.

You need a reliable electrical tester or a wiggy.

1 Like

You may need a better non contact tester. I have one that goes off if it gets with in a foot of any power source. and another one that will only go off when in close proximity. as poked into a receptacle. or on a live wire. Much better tester.

the good tester is a FLUKE
the bad tester is a southwire.

1 Like

You need to Google Capacitive voltage tester. Understanding Capacitive Coupling

In the future the test you want for live dead fronts is to lightly touch it with the BACK of your hand… The voltage sniffer test is unreliable for panel covers.

Milwaukee makes a good non contact tester.


A non contact tester with a sensitivity adjustment works great.

doesn’t anybody do the lick test anymore ???


For some reason, I thought that was plumbing specific. Going to incorporate it into my electrical inspection from now on. :wink:


I have 2 Milwaukee sniffers and another brand (can’t remember name at the moment) that I bought at an election supply house. They all give slightly different readings. If it’s set for higher sensitivity, you can get false readings quite often.

Excellent advice…

1 Like

I guess his agent was too chicken, relied on their hand.

1 Like

I have been doing that for so long I doubt I will ever break-out a voltage tester. It is muscle memory now.


Right hand, not left for those that do it. I prefer voltage testers, false readings or not to keep my internal ticker ticking. To each, there own way of checking. :wink:

1 Like

I just bought the FLIR VP50. It has dual sensitivity. The flashlight is worthless but other than that I like it a lot. It even vibrates.

1 Like

Max, hopefully by now you read the link I posted to Capacitive coupling in the 5th post of this thread. If you did I trust you paid particular note to the part that described coupling to grounded and ungrounded boxes. In your case I would suspect, since the sniffer went off but the Agent was not fried. that the panel had poor to no grounding. An earlier thread on this subject dealt with ungrounded metal work boxes around outlets and the fact that sniffers would light before the tester touched the outlet.

Six people are now re-reading that article. Hope your one!


I have my people for that. :stuck_out_tongue_winking_eye:

1 Like

Hey everyone. Sorry for the late reply.
Wow, really appreciate the feedback from you all.
I will read up on those articles and try to understand better. I guess some tools are not accurate and rather not be used.
Anyway, will keep you posted.
Have a great day everyone.

About the only thing I use a non-contact tester for is to see if two-wire outlets are live and the occasional empty light socket.