DIY Polarity Tester for Line Voltage Wiring

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01:51:02

Left is 3-prong polarized plug to insert into a line voltage outlet. BOTH neon lamps must light when plugged into wall outlet.  If they do not light then something is wrong with wall outlet wiring.

published 4 years ago

jason9

4 years ago

Or if it’s GFCI then it’ll instantly trip.

lmccoig

4 years ago

This is to check wall outlet plug in to see if correctly wired.

jason9

4 years ago

I know that. I'm just saying that since GFCIs trip with more than 5mA through the ground pin this circuit will for sure trip a GFCI thereby shutting off both lamps and giving a false negative when the outlet may be correctly wired.

lmccoig

4 years ago

Hi jason9, I tend to think of GFCI in wet areas or outdoors. I have tripped GFCI with volt meter and know they are sensitive. Thanks for sharing your comment.

jason9

4 years ago

Yeah I just wanted to mention that because in the U.S. GFCIs are pretty common (present in almost every bathroom I think) and if a plug is on the same circuit as a GFCI then it’s effectively GFCI too and then you have to hunt down the GFCI so you can reset it after you trip it. So basically a plug can unexpectedly be GFCI when you otherwise wouldn’t think it to be. Although most of this information isn’t personal experience so I don’t know how true it is. All I personally know is that my bathroom has a GFCI in it.

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