• Author Author: kmikemoo
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Multicomp Pro Non-Contact Voltage Tester vs. Real Life

kmikemoo

After completing the Multicomp Pro Non-Contact Voltage Tester - Review, I asked myself "Why don't I use this type of tool more?"  Then I started thinking of some of the events that distracted me along the way.  This blog just might be my version of the bloopers reel.

 

Does a good ground really matter?

I know it does, but how much?  I call this the Flamingo Testing Method.  Stand on the sneaker.  Measure.  Stand on the bare foot.  Measure.  Hope Amazon finally delivers the grounding strap today.  Repeat.

image

This was a preliminary test.  The ones used in the roadtest didn't involve this method.

 

Everything is Hot

Generator controller with 12VDC from an AC adapter.

 

Label maker.

 

Battery Powered Stick Vacuum.

 

Ground Wire

 

I'm not tough enough to hold onto an energized conductor.  I still haven't sorted this out.  There is no measured voltage on the ground wire (millivolts that do not fluctuate).  Fluctuating millivolts would indicate an open.  I tested the grounding (Earthing) circuit and it is in tact.  6" steel water line.  No measurable drop in the bonding circuit.

 

This is why I don't use this type of tester more often. image  At least it fails safe.

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  • The 9V labeller and the vacuum probably have wall blocks that are double-insulated and don't have a ground connection to the secondary side. The dc coming out is dc between the two output wires, but not necessarily dc with respect to ground. I think you'd find, if you looked at the output wires with a scope [just the tip of the probe, so that the measurement is with respect to the scope ground, otherwise if you clip the probe ground to either wire you're earthing the secondary side], that they have some 60Hz/50Hz on them.

     

    With the ground wire one, I think, effectively, you're doing the test backwards. Your body has capacitance to the electric wiring all around you as well as ground, so rather than your body being a true ground reference, it's always got some ac voltage on it. If you want to experiment with it, place an insulated mains lead where you can reach it with your other hand, back the probe away from the earth cable until it just doesn't register, then move your free hand closer to the mains cable and the probe should start to register again [if my theory is correct]. Basically, the probe is working in reverse and the handle is sensing the ac potential on you, whilst the tip is doing the capacitance-to-ground reference part of things [the electronics in the probe can't tell the difference].

  • in reply to jc2048

      Wow!  I think you're right!  And... it's just a little disturbing.  It could mean that I have the equivalent of 40VAC on my body.

    I didn't play with the wall warts yet, but the ground wire was a fast test.  The beeping goes away if I touch the bare copper.  It also goes away if I grasp a power cord.  I'll try your test method tomorrow.

    Again... wow.  I'm really starting to rethink my propensity to not wear the ground strap when playing with electronics.

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  • in reply to jc2048

      Wow!  I think you're right!  And... it's just a little disturbing.  It could mean that I have the equivalent of 40VAC on my body.

    I didn't play with the wall warts yet, but the ground wire was a fast test.  The beeping goes away if I touch the bare copper.  It also goes away if I grasp a power cord.  I'll try your test method tomorrow.

    Again... wow.  I'm really starting to rethink my propensity to not wear the ground strap when playing with electronics.

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