Finally some polite dialog!
A few pictures may help explain. This is a simple receptacle tester. First picture shows ok. (35 years ago here I had home 200A service installed professionally and inspected as before retirement I had my Company to run as an electronic technician/ troubleshooter. Afterwards in evenings I wired garage, other buildings...yes to code). Of course... "You should read up on "voltage drop." When you carry current on a wire, the voltage is NOT the same at both ends of the wire." Yes, I know a little bit about voltage drop. Ohm's
Law is the cornerstone of it all. Voltage drop directly relates to resistance of the conductor wire (length, composition, size) and amount of current flow through it.
Second picture shows a faulty 6 plug adapter, open ground...3rd picture slight twist and it makes contact...all is well. (I'm tossing that adapter though).
Fourth picture I simply clipped in hot, neutral and tester shows open neutral. Last I clipped in a jumper from neutral to ground...tester shows all is well.
FYI I just now got off the phone with our local service provider speaking with an engineer, I explained scenario to him, he agreed I was correct.
Why the 3 vs 2 prong plug?
Years ago the a.c. outlets weren't polarized. You could plug an appliance in either way. Tremendous shock hazard since the metal case could be hot with respect to ground (metal water pipe).
Three prong polarizes , can only plug in one way. Hot, neutral, ground.
As I said...agreement with provider engineer...ideally you want zero volts (again...ideally) or close as possible between neutral and ground.
For what the OP wants to do, installing a 2 prong 12v a.c. adapter this will be fine.
For a little more expense and work sure, he could put in a driven ground rod wired into an GFCI receptacle ground, one leg of the 240v (120v hot) then center neutral.
I simply wired in a 3 prong outlet, since there was already a metal buried pipe going out I used that ground.




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