I have a SouthWire 10040N multimeter that has an autosensing AC circuit that lights a light at the front of the meter when it detects AC. I'm wondering why it lights up when it passes some people (arms, leg, hand, torso, etc) and others it doesn't. The light doesn't stay on like when I press it to an AC outlet, but it flashes on and off as I pass it across some people's bodies - while other people it doesn't...

I can press the meter to the battery pack of a drill and press the trigger and it won't light. It will sometimes flash when pressed to the motor of the drill when on.

I'm just more curious about the sensing on human bodies and why it doesn't do it on some people. Do we have robots among us?

Operating Manual

Spec Sheet

 

What if you repeat the test with the same "lot" of positives and negatives in further sessions?

 

It's an active device, using some sort of capacitive coupling/sensing. At least that's what I believe causes it in some "squeakers" or non-contact detectors made to warn of energized electrical wiring or devices. Move it very quickly over nearly any surface and you'll get something.

 

Check if they are wearing "electrically insulating" vs "static disipating" shoes.

 

"NOTE: The detector is designed with
high sensitivity. Static electricity or other
sources of energy may randomly trip the
sensor. This is normal operation.
NOTE: The non-contact voltage detector simply detects the presence of voltage -
it will not measure and display the voltage on the LCD screen"