50 amp plug in

pawagan · February 09, 2007, 12:54:07 PM

When you have a 50 amp plug in, how much is the voltage coming into the coach?

The reason I am asking the question, is due to a friend's request to have a 50 amp service installed at his summer home, so he can hook his RV to service.
I wasn't aware that you could have anything but 220 volts if you had a 50 amp service to plug into.

I dont recall reading anything about this in the magazine.

Please let me hear from someone.

edvanland · February 09, 2007, 02:05:11 PM

I don't understand all the electric things, however I do know with a 50 AMP plug you only get 110 in the coach. Mine has a 50 AMP plug. When I got it I wired my own 50 AMP circuit in the garge so I could plug in. Yoy will get more knowledable people who will reply but that is what I did.
ED
MCI 7

Jerry32 · February 09, 2007, 02:22:42 PM

50 amp is essentally 240v with two legs of 120v center tapped with the nuetral. That gives you two 120v 50 amp legs.

gumpy · February 09, 2007, 02:43:32 PM

Jerry is essentially correct here. A 50 amp power outlet is 240 volts. It is composed of 4 wires: 2 hots, 1 neutral, and one ground. The two hots are 120 volts each in reference to neutral, but out of phase with each other. These two hots are typically used for 240 volt applications in a household environment.

However, in a coach, there is generally no 240 volt equipment. Often, one leg of the connection is used to power the entire coach, but it is not uncommon to use both, since most coaches use a standard house breaker box, which is composed of the same 4 buses. But the usage is typically all 120 volts, or one of the hot legs paired with the neutral.

Your buddy is correct in wanting to install a 50 amp, 240 volt outlet to plug into. He should use a standard RV power pole, with the standard 4 prong receptacle.

DrivingMissLazy · February 09, 2007, 03:23:03 PM

Quote from: edvanland on February 09, 2007, 02:05:11 PM
I don't understand all the electric things, however I do know with a 50 AMP plug you only get 110 in the coach. Mine has a 50 AMP plug. When I got it I wired my own 50 AMP circuit in the garge so I could plug in. Yoy will get more knowledable people who will reply but that is what I did.
ED
MCI 7

The statement above is incorrect. The correct terminology is 50 amp, 240/120 volt service. There are two legs of 120 volts at 50 amps available for a total of 100 amps, or one leg of 50 amps at 240 volts available, or any combination of the two, as long as you do not exceed 50 amps per leg.
You could operate an electric range that requires 20 amps at 240 volts and any combination of other electrical devices that require not more than a total of 60 amps at 120 volts. This 60 amps would have to be split at 30 amps each for each leg.
Richard

TomC · February 09, 2007, 11:52:17 PM

I have my bus wired straight 120v. I do have a 50 amp plug, but only use one side of the plug. I have read many a post where campers have plugged into an improperly wired 50 amp plug and gotton a full jolt of 240v into the coach. If you have doubts as to the wiring of the plug, have a volt meter with you. Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC

Gary '79 5C · February 10, 2007, 04:19:52 AM

Tom is right on with the manner to check the wiring on the campsite side of the receptacle. If that is incorrect, you may have higher voltages within your coach here they should not be.. That is 240 on a 120 plug within the coach.
To further the point, Coaches like homes will have two incoming 120 legs (circuits) which get distributed thru out. If you only wire to one side it provides you protection, but you limit your 50 Amp plug to essentially 25 amps. 50 amp service is 25 amps per leg, Two legs coming in, each 120 VAC.

If you can live with utilizing only one side of the 50 Amp 240VAC plug in, and manage the electrical loads, That is a great manner to safeguard yourself and your equipment.
I rarely plug in as I use the coach to get from here to there and donot stay in the coach at the end of the journey. That will come later when I retire ( or quit at my present job, there is no retirement in site for me, always something to do)
Hope this helps.
That simple check of Tom's will save $$$

DrivingMissLazy · February 10, 2007, 05:02:57 AM

Quote50 amp service is 25 amps per leg, Two legs coming in, each 120 VAC.

I hate to dispute you Gary, but that statement is absolutely incorrect.
50 amps service consists of two legs coming in, each 120 volts at 50 amps per leg. If you only use one leg, as Tom says he does, he has 50 amps at 120 volts for a total input capacity of 6,000 watts. If he used both legs he would have a total capacity available of 12,000 (12kw) watts.
For those using a 30 amp service, 30 amps at 120 volts provides 3,600 (3.6kw) watts. I have never heard of any standard service that provides 25 amps of service.
Richard

Stan · February 10, 2007, 05:29:33 AM

quote "Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC" unquote

At both the power pole and the gen set the neutral is tied to ground. You should measure the same voltage to ground as you do to neutral.

DrivingMissLazy · February 10, 2007, 05:34:07 AM

Quote"Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC"

At both the power pole and the gen set the neutral is tied to ground. You should measure the same voltage to ground as you do to neutral.
Stan

Thanks Stan for pointing that out, I missed it and that is very important for everyone to know. The only place you would not, should not, can not (to be safe) read any voltage is between neutral and ground.
Richard

TomC · February 10, 2007, 07:14:03 AM

Stan- thanks for that very important correction on my post. No voltage between the neutral and ground is what I was supposed to say-and a very important reading so you know if there is any "shorting" situations with the wiring. Good Luck, TomC

Gary '79 5C · February 10, 2007, 07:14:43 AM

Richard,

Thanks for the clarification, YOU are correct. The AWG size required for the 50 amp service warrants the full 50 AMP EACH LEG.
Not sure now, what I thinking then, but you have cleared this up for me and hopefully I did not screw toooo many others up before.

Rich,
thanks for helping this po boy from Weirton WVa with this.

I will wait for the second cup of coffee to set in before typing.

DrivingMissLazy · February 10, 2007, 11:01:42 AM

Quote from: Gary '79 5-C on February 10, 2007, 07:14:43 AM
Richard,

Thanks for the clarification, YOU are correct. The AWG size required for the 50 amp service warrants the full 50 AMP EACH LEG.
Not sure now, what I thinking then, but you have cleared this up for me and hopefully I did not screw toooo many others up before.

Rich,
thanks for helping this po boy from Weirton WVa with this.

I will wait for the second cup of coffee to set in before typing.

Gary, come on down to Spencer & I will furnish the second cup. LOL

Gary LaBombard · February 10, 2007, 11:45:41 AM

I did not see this post until I posted on the one above it, if phil or Richard want to combine it with this post is fine with me but this may help with assurance you have good shore power connected your RV /Bus before actually connecting up to it. My post has to do with Phil's near catastrophe on his bus at a camp ground that was improperly wired.
Sorry for the double posting on this.
Gary

pvcces · February 10, 2007, 08:36:31 PM

That business about the full wire size for 50amps per leg does a nice job of clearing up why 50 amp service has to be 240 volt; if the power was furnished as 120 volts only, then the neutral would have to be two neutrals or about a three gauge wire, if it was even legal to use only one neutral.

Tom Caffrey