Help identifying shore power wires

[DefinitelyMe]

So....... last wired in the dark ages, when everything was black. This is a 50A, 125V inlet (NOT a 125V/250V). Three wires. Ground appears obvious, but which is neutral and which is hot? Terminals are labelled 'x' and 'y'. I've spent at least an hour on Google and thus far failed completely.

If nobody knows, is there an easy way to find out with the use of a multimeter, and without energising the system? The best I can think of is to back-feed the AC power system through a 110V outlet and then test the inlet to determine the terminals. But that seems kind of sketchy......

[ItDepends]

Because AC power systems are SO dangerous if miswired, I am not going to give you direct advice, other that to say you might want to look up how to wire NMEA standard plugs...

Lots of information out there.

[smac999]

you should be able to figure it out by measureing the dock side. and just match the prongs. but that assumes the dock is wired correctly. you'll have 120v Hot-Nutreal 120v H-Ground and 0v N-G

once you test all combos you should know which prong is which on the dock side just line up with yours.

or ohms test it from the shore plug to the main breaker input (with breaker off). at the breaker / panel you should know which is hot or netreual. you might need a long wire to test

[DefinitelyMe]

Originally Posted by smac999

or ohms test it from the shore plug to the main breaker input (with breaker off). at the breaker / panel you should know which is hot or netreual. you might need a long wire to test

Yea that might be the way to go. I can't test the dock side unfortunately, since the dock has either 30A 125V or 50A 125V/250V. So there's no match there.

[DefinitelyMe]

Originally Posted by ItDepends

Because AC power systems are SO dangerous if miswired, I am not going to give you direct advice, other that to say you might want to look up how to wire NMEA standard plugs...

Lots of information out there.

I think you mean NEMA plugs, not NMEA which is something entirely different. I am familiar with the standards, just not the non-standard stuff like this. Any sources for this specific setup? I've tried and failed to find them.......

[smac999]

are you converting it to a 30a 120v plug?

[DefinitelyMe]

Originally Posted by smac999

are you converting it to a 30a 120v plug?

Yes. Boat loads are not what they used to be. Used to run an electric stove and A/C. Now just a charger and some outlets. Why do you ask?

Actually it's been running from a 30A 125V supply for some time, via a pigtail adapter.

[Sailmonkey]

A picture is worth a thousand words.

[DefinitelyMe]

Originally Posted by Sailmonkey

A picture is worth a thousand words.

Attachment 263748

Brilliant, that's all I was looking for and what I failed to find in at least an hour of googling. So, whereas mine are labelled X and Y these are now designated W and Z, neutral and hot respectively. I'm going to go with that. If it's wrong I should get a reverse polarity light immediately. I won't blame anyone else if I burn the boat down. :-)