I'm making a DIY wall mounted pull-up bar (I'm too tall for the normal kind, and can't fit a commercial wall bar due to a sloped ceiling) and I just mounted the heavy duty brackets I'm using, but I've run into a problem: My AC wire sensor and AC sensor pen go off when I check the left bracket which is mounted to the king stud of my door--along which the wires for my ceiling lights are mounted. And when screwing into the wall the lights did flicker just a small amount once with one screw--but light flickering isn't uncommon in my area being on the end of the line and my house is kinda old. However, the bracket is safe to touch as are the screws. And when I took it out of the wall screw by screw the effect did not disappear regardless of the screw being one that went in fine, or the one that might have caused the flickering. Also I did not hit any metal wire protectors in the stud.

I'm wondering if what my sensors are detecting is an induced current in the bracket and screws? I have a Tv mount and several other things mounted on different studs with wires running relatively near them that are definitely fine but still set off my detectors. Plus, my house is old with thick solid core wires (Could wires moving while drilling cause flickering?).

No breaker's have tripped, everything else on the circuit is fine. Nothing accept the one flicker. I'm just not sure what to do. Should I be worried or just call it a day? Any advice would be appreciated, thank you.

  • So the effect occurs with no screws in place? The bracket is probably just passing induced current, which is what your non-contact tester senses.
    – isherwood
    Apr 6, 2018 at 17:07
  • 1
    It is possible to energize a screw, nick the insulation of a conductor but not break the conductor itself.
    – Tyson
    Apr 6, 2018 at 18:59
  • just jump and grab the bar each time, never touching the floor and bar at once... just kidding, you should be fine no matter what. those contactless voltage sensors are FAR from definitive; it usually beeps on my face for example...
    – dandavis
    Apr 6, 2018 at 20:44

1 Answer 1


As others have already commented, the touchless voltage detectors are often too sensitive. I've found that if I keep a finger on one side of the detector tip while checking individual wires in a box it takes care of the oversensitivity. Try laying a finger on one side of the detector pen tip while checking for voltage on the bar or bracket. If it still beeps, get a multimeter and extend a connected wire from the bar down to where you can test between it and the grounded (third) prong of three-prong outlet or other ground connection to see if you have voltage. Using this wire extension from the bar setup you can also check for voltage between it and neutral, and between it and hot. Record your findings and comment here.

It is possible you may have skinned a wire with a mounting screw without breaking it. It is also possible that you are not getting shocked because the other surfaces you are touching is not sufficient to ground you, especially if you are wearing rubber soled shoes. One day you may grab a hold of the bar in bare feet, expecting to do a few reps and find yourself needing a defibrillator instead. I think it is worth doing a few more tests to be on the safe side.

  • 1
    Well, I have tested it for a voltage between ground and got nothing--didn't test with neutral or live cause I though ground would be good enough. I'm thinking it is induction since it is happening in my TV mount and some screws for pictures. Kind weird how even a screw a meter away from the wire is setting things off though. Do solid core wires create a stronger magnetic field and thus induction effect than stranded? Oh! and I am protected by my carpet, socks, shoes and wooden pull up bar between the brackets. And workout gloves. I will test it with the finger trick you mentioned. Thanks. Apr 7, 2018 at 21:33
  • Yeah, let me know. I believe the finger trick will eliminate oversensitivity and false positives. Just touch the side of the tip and hold the other side to whatever you want to test. Apr 7, 2018 at 22:14

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