120v or 240v at 50amp receptacle?

[Lateagain]

So the tech just left and advised me that my RV plug shouldn't be wired with different phases going into the coach? It doesn't make much sense to me to have a plug with the ability to spread the load out and load it all on one phase at the breaker... enlighten me... I'm a lineman by trade and my way makes sense, but i'm willing to learn

[Terry W.]

Ok I wired my with 2 120v legs 1 neutral 1 ground and all is well. So says the meter and surge protector

Sent from my XT1585 using Tapatalk

[flybouy]

It is a split phase connection. This may help. http://photobucket.com/gallery/user/...MS5qcGc=/?ref=

[Lateagain]

Thanks for assuring me I'm not crazy...

[Racebug]

I would assume it could also be wired off the same leg still with 2 50 amp breakers?

[Lateagain]

Originally Posted by Racebug

I would assume it could also be wired off the same leg still with 2 50 amp breakers?

I would think so, his concern was that opposing phases would damage chargers, inverters and electronics... my concern was only chargers and inverters if he was correct.

[JRTJH]

Your electrician isn't "crazy" and neither are you. I'd make a guess that he was talking about wiring for a 30 amp RV plug vs a 30 amp "dryer plug". One is single phase, 120 VAC (RV) and the other is two phase, 240 volt (dryer). Physically the plugs look the same, but severe damage would be done to your RV if you plug the power cord into a "dryer plug"....

ALL 50 amp RV plugs are "two hot lines" a neutral (common) and a ground. Measuring across the two hot leads will read 240 VAC and from either hot lead to neutral or ground will read 120. (that's the same as a 30 amp dryer plug).

An RV plug will read 120 VAC from the hot lead to either the neutral or ground and 0 VAC from the neutral to ground.

So, in all probability he was talking about his experience wiring a 30 amp RV plug and didn't explain the difference between 30 and 50 amp RV plugs......

[xcntrk]

He's talking about the different types of 240v circuits. Take a welder or even the OLD style dryer plugs. They have only 3-prongs, 2 are 120v hot (high and low side wave) and one is ground. No need for neutral as the appliances on this circuit use both 120v waves (aka a single 240v phase). Now take your modern dryer or RV plug. It's 4-prong with the addition of the neutral. That's because portions of the appliances running on that plug need 120v (requiring the neutral) and portions require the full 240v. This is where you get both 120v and 240v phases simultaneously.

A perfect example is a modern electric dryer. The display, light, and general electronics run on 120v power while the heater & motor run on 240v. All this comes from the same plug and the addition of the neutral allows the 120v side to operate correctly.

To make it more confusing, all of the appliances including the 15k btu AC's, in your 5th wheel are 120v devices. When they're all running (including x2 AC units) the amp demand is greater than a typical 120v circuit can support. Therefore the RV uses the 50-amp 240v circuit to in effect bring into the coach TWO independent 120v circuits in order to meet the load. This is the both phase requirement being mentioned, the high wave phase and the low wave phase, just like a panel box at home.

Or something like that

[xrated]

50Amp RV Plug supplies......
One 50amp (120volt) line using one of the hot lines to neutral.
One 50amp (120volt) line using the other hot line to neutral

Total wattage available....12,000W
This of course is assuming that everything is wired correctly, in good operation condition, and the power pedestal has the proper size feed to it that supplies the power to the RV receptacle on it.

And you are correct, it is the same type setup that is used in service entrances for your house, a single phase center-tapped transformer providing the power.

[Bob Landry]

A common misconception on phase... 240 service is not dual phase. It's still single phase power. When an electrical source is said to be multi-phase, that refers to voltage and current component of the sine wave being out of phase with each other. The voltage is still 60HZ with the two halves of the sine wave being 180 degrees out of phase with each other, but voltage and current remain in phase. Multi phase power is used mostly in commercial equipment to increase starting torque of large electric motors, seldom if ever in residential or recreational equipment.