50 amp outlet for RV's

[schrederman]

Two phase power feeds most homes and businesses in the world. You can call it split phase, or twin phase, etc... but there's still 2 phases... Each of the 2 phases is 180 degrees out of phase with the other. At peak voltage from neutral they are double that from each other because one is positive and the other negative. The neutral leg in alternating current circuits does eventually end up as ground. The power company transmits the hot through wires and the neutral side through Mother Earth. The neutral is carried from the transformer on the pole to the load (home or business), for current balancing. However for current carrying capabilities, it should be the same gauge as the hot conductors. The ground wire in home wiring and cords usually is smaller gauge and not intended to be a current-carrying conductor.

What I saw was a standard, 2-phase, 220 VAC wiring scheme with a neutral and ground, just like the one I wired for my compressor. The power coming in is 2 - 110 VAC circuits that in my case had to be combined to give the me the 220 VAC I needed. This is truly simple. I do test when I go to parks, so I don't wind up with a fried converter or worse. The statement about not plugging into a 220 VAC outlet is wrong.... because it's the same as 2 - 110 VAC legs, which are needed for 50 amp RV service. The only instances in which they are used as 220 VAC is when the 2 hot wires are fed into the same load. In all other applications only 1 hot and the neutral is fed to the load. If you use a 50 to 30 amp converter to plug in, the converter continues only one of the 110 VAC legs into your RV cord. The other ends in the converter and does nothing.

Lots of misunderstanding by the electrically challenged... but lots of good info here, too... But hey... I'm not good at accounting, so don't feel too bad...

[fast murray]

Originally Posted by schrederman

The statement about not plugging into a 220 VAC outlet is wrong.... because it's the same as 2 - 110 VAC legs, which are needed for 50 amp RV service. The only instances in which they are used as 220 VAC is when the 2 hot wires are fed into the same load. In all other applications only 1 hot and the neutral is fed to the load. If you use a 50 to 30 amp converter to plug in, the converter continues only one of the 110 VAC legs into your RV cord. The other ends in the converter and does nothing.

Lots of misunderstanding by the electrically challenged... but lots of good info here, too... But hey... I'm not good at accounting, so don't feel too bad...

That statement was spot on. That's the reason the NEC changed in 2014 requiring multi-wire branch circuits carry a separate neutral with each hot unless being fed by a breaker that opens all phases using that neutral. That is ok here using a double pole breaker to feed the receptacle but the intent of the code is to eliminate the chances of losing a neutral and causing damage. If the RV convertor or some other expensive piece of electrical equipment is connected to A phase and a toaster is connected to B phase and you are operating the toaster you will very likely destroy the more expensive piece of equipment when you energize the toaster by putting the two in series across a 240 volt load. The toaster will likely be ok since the more sensitive load will act as an expensive fuse protecting the toaster.

BTW, there really is no 2 phase, only single phase and three phase. I get what you're saying but it's still called single phase. Just a terminology thing.

I play an electrician by day to fund this hobby called life

[fast murray]

Originally Posted by OldCoot

Have seen a lot of home 100A & 200A boxes where certified electricians have connected the neutral and ground to the same lug/terminal in the main box. The electrician could have if there were a ground wire, done the same in this incident, but evidently did not run a ground wire.

While that would work, it would be incorrect as the receptacle needs to be fed with a separate neutral and ground wire. 8-3 wg is what's needed here.

[WDK]

Originally Posted by TGR

It looks like the view of the neutral/ground busbar in post #6 is partially obscured by the circuit breakers. However the busbar is visible in the slots without circuit breakers. The two white neutral wires are wired to the neutral/ground busbar and so are the two green wires.

Fast murrray is correct, residential homes are supplied by split-phase power, not 2-phase power.

This was my thought as I looked at the picture but from the responses I thought I was not seeing something so I made no comment.

WDK