Shore Power at Home

Obviously I'm new.  My question.  Is is possible to safely connect a 50 amp RV system to a 220 VAC dryer outlet at home?  If so, is there an adapter available to make the transition?  Thanks in advance.

Fred and Nit - New RV'ers and loving it.  However today"s diesel prices may somewhat dampen out enthusiasm.

I do not know if there is an adapter but I just did a restore on my HD, let me see if it restored what I just deleted

Here is one URL, I know NOTHING about this company and thus can not recommend either way

http://www.pplmotorhomes.com/parts/rv-power-cords/rv-hookup-50-amp.htm

But you can download the photo, print it out, and take it to a local RV or Electrical supplier.

I have a 30 amp outlet in my back yard. though it's only got a 20 breaker feeding it (the idea is simply battery maintance and possible furnace... No AC load on that line) 

Can't plug in yet, but when I installed the outlet all I had was a 30 amp trailer... Now I have a MH which can use more

John In Detroit said:

I do not know if there is an adapter but I just did a restore on my HD, let me see if it restored what I just deleted

Here is one URL, I know NOTHING about this company and thus can not recommend either way

http://www.pplmotorhomes.com/parts/rv-power-cords/rv-hookup-50-amp.htm

But you can download the photo, print it out, and take it to a local RV or Electrical supplier.

I have a 30 amp outlet in my back yard. though it's only got a 20 breaker feeding it (the idea is simply battery maintance and possible furnace... No AC load on that line)?

Can't plug in yet, but when I installed the outlet all I had was a 30 amp trailer... Now I have a MH which can use more

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John and Fred,

Both the 50 amp and 30 amp RV receptacles are available at HomeDepot. They are labled right on the box "For RV use"

Fred and Nit said:

Obviously I'm new.  My question.  Is is possible to safely connect a 50 amp RV system to a 220 VAC dryer outlet at home?  If so, is there an adapter available to make the transition?  Thanks in advance.

Fred and Nit - New RV'ers and loving it.  However today"s diesel prices may somewhat dampen out enthusiasm.

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Fred,

In a word, NO!!!! An RV 50 amp circuit is NOT 220V. It consists of two 120V legs. Never connect any 220V circuit to an RV. All circuits in an RV are 120 with some exceptions in conversions such as the Prevost. Sometimes they use 220V for the stove. They might even use it for the clothes dryer but I'm not sure.

Jim Dick said:

Fred,

In a word, NO!!!! An RV 50 amp circuit is NOT 220V.

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uh,  |110-0-110| or 220 volt split phase,  The explanation is complicated but that is how a dryer is wired, Trust me on that, the heat element in the dryer is 220 volt (conects only to the two outer legs) but the timer, motor and control board (if any) are all powered by 110 volt.  Thus the standard dryer outlet is 110-0-110 (or these days it is 120-0-120 but alas, that 10 volts makes no difference)

Most folks just call it 220, but the full name is "240 volt split phase" and the split, is, of course, 120 volts.

That way,,, If you are running everything on one leg of your 50 amp system, you get up to 30 amps (dryers are usually fused or breakered at 30 amps) max on one leg and "Common".  if you are running everythign possible you have 30 amps on both legs (assuming a perfectly balanced rig, which, of course, is a dream) and no current at all on the common.

In days of old, when folks were bold, common might well be the ground itself,,, However that has not been code since about 1942 (WWII to be specific)  I've read some very old electrical books.. Older than I am (I'm a 51 model myself)

John,

Then I would assume the two legs are different phases. We've had a lot of discussion about hooking 220V. If we are adviising someone they can do it then we better provide a step by step explanation. There seems to be too much confusion on just what a 50amp circuit entails.

Fred and Nit said:

Obviously I'm new.  My question.  Is is possible to safely connect a 50 amp RV system to a 220 VAC dryer outlet at home?  If so, is there an adapter available to make the transition?  Thanks in advance.

Fred and Nit - New RV'ers and loving it.  However today"s diesel prices may somewhat dampen out enthusiasm.

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Safest bet: Get a 50 amp RV receptacle at Lowes or Home Depot (or even by mail from CW if not available where you live) and have an electrician come and hook it up where you want. That way it'll be done properly.

BruceinFL said:

Safest bet: Get a 50 amp RV receptacle at Lowes or Home Depot (or even by mail from CW if not available where you live) and have an electrician come and hook it up where you want. That way it'll be done properly.

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Hi Bruce,

Without a doubt you are correct!!! I was just reading a note on the American Coach Yahoo Group from a guy that zapped his charger. His brother wired in 120V on both sides of a 30amp outlet!!! If in doubt, let the pro do it. At least they will be liable.

John In Detroit said:

...the heat element in the dryer is 220 volt (conects only to the two outer legs) but the timer, motor and control board (if any) are all powered by 110 volt.

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Just for clarification, whilst that's true for domestic/home dryers, it's not true for Splendide combo washer/dryer used in the majority of RVs. They're 120V, single phase only - no provision for 220V. Check your washer/dryer owners manual and your coach's wiring diagrams. You can also check the manufacturer's web site.
[edit]Fixed link.[/edit]

Multiple post reply:

RE: "True of home, not RV dryers"  yes, he was speaking of a home dryer outlet and so was I,  I've done considerable work on one of the old dryers in my home.  Replaced teh heat element more than once, assorted bearings and rollers, finally replaced the entire dryer.

Re: different phases, no, same phase.  It is not multi phase, it is split phase.  both legs are totaly in phase so if you label them

A(120v)B(120v)C and you measure A to B, it's 120 volt, Measure B to C it's 120 volt, Measure A to C it's 240 volt,  but the phase is the same (as cited above) if you measure A to B and C to B however then yes, the phase is backwards.

but to add they must be in phase.  Hence the label "Split phase" because a single phase is split between the two legs.  The transformer is center tapped.

And finally re: hooking A & C up to a 30 amp outlet... Very bad idea (As that one person found out) the 30 amp outlet in my back yard is a proper 120V line

Interesting fact: The generator on my RV is 120 volt only,  it can not power 240 volt gear w/o a transformer.  Why they did this I do not know unless it has a single 120 Volt winding (it has 2 30 amp breakers)

John In Detroit said:

he was speaking of a home dryer outlet and so was I

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Since your message began with the quote "An RV 50 amp circuit is NOT 220V", it wasn't obvious to me that you were talking about a home dryer, which is why I figured I'd better clarify that they're different. We really don't want folks hooking up their RV dryer incorrectly. I have no doubt that you understood what you meant.

I've done considerable work on one of the old dryers in my home.

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Me too. Used to do it for paying customers at one time.

While most 50A RVs only use it as a pair of 120V feeds, a standard RV 50A outlet is most definitely a 220V hook-up and some (though not many) RVs do in fact have 220V appliances, e.g. a residential-style 220V stove. 

Tom said:

Since your message began with the quote "An RV 50 amp circuit is NOT 220V",

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Oh, good point, however wrong poster, That was someone else whom I quoted

But you did make a good point... of course some RV's are not entirely RV stock, as someone else pointed out

I do know it's a lot of fun wiring up stuff on the rig... I get to slide under it (there is enough ground clearence for 320 lb me to slide under it) and sit up, actually and work up inside the frame of the "Truck" part and so long as I'm not too close to tires, batteries, jacks and the like there is plunty of room to work

Added some daisy chain RV outlets to power other rigs in the event of power fail sould I feel kind, also to run pre-existing extension cords for use on the table should I wish to grill with electric insted of propane.  added a side view video camera, and of course had to run all the wires for all this stuff.  the side view camera lines up with the gas cap, should make re-fueling easier, much, much, easier

John In Detroit said:

I do know it's a lot of fun wiring up stuff on the rig... I get to slide under it....

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Me too John, until I recently had the factory guys rewire some stuff that had been incorrectly wired when the coach was built (I'm not fixing their errors), and I witnessed this. I'm not as keen to slide (or wriggle) under the coach any more 

This one has been bugging me for several years. I've even asked electricians, technicians and engineers and never received a straight answer. My understanding was also clouded by my background in UK power distribution systems which are quite different from those in the U.S. So I did a little research of my own.

John was right on with his explanation of split phase (a single phase supply fed by a center-tapped transformer), which applies equally to our domestic electrical service and that of 50A service at campgrounds.

Here's the wiring diagram (14-50R is the receptacle used for 50A service at a campground).

When we plug our RVs into 50A service, our appliances and a/c units are shared between the two 125V legs; Some are wired to one leg and some to the other. (Yes, some high-end coaches have 250V appliances which will be connected across the two legs, rather than between one leg and neutral).

A little light reading (no pun intended):

Wikipedia on split phase systems.

Wikipedia on applicable national electric code.

Fred and Nit,
Confusin', ain't it.
If you refer to the diagram provided by Tom, you'll see that your RV cord has a  NEMA 14-50 plug end. Your dryer receptacle most likely has the NEMA 14-50R receptacle. You can build (or have built) a cord adapter with the appropriate ends and it will work fine. The only thing to be aware of is that no matter how big the receptacle is, you will still be able to draw only 30 Amps from the receptacle. Any more and the breaker opens.

As to the (mistaken) belief that this is polyphase, it is single phase. The diagram shows very well how this works. Also, I've heard it stated that only a very few coaches have 220v appliances. Actually, if you have standard washer/dryer hookups installed, the dryer receptacle can be 220.

One last observation before I put away my soapbox. The diagram shows the white wire as the sys gr or system ground. Never confuse this with the grounding conductor. Even though they are connected (bonded) at the breaker panel, never, never, ever reverse or connect the two at the receptacle or in the trailer. On an unbalanced load, the white wire or neutral conductor becomes a current carrying conductor and swapping with the grounding conductor could allow dangerous voltages to be present at the trailer.
Q

Thanks Quasi.

quasi said:

You can build (or have built) a cord adapter with the appropriate ends and it will work fine.

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PPL sells a 50A extension cord with the right connectors on it. One reason I didn't suggest this is that, since a domestic dryer is 220V, the neutral conductor carries little or no current and, since I didn't know the applicable electrical code or how Fred's house is wired, I didn't know if his domestic dryer receptacle might be wired with a smaller neutral conductor. Running a bunch of 110V loads in his RV on a circuit with a small neutral wire  might cause a fire and, since he specifically asked if it was safe, I honestly couldn't answer that. Hopefully, someone who knows the electrical code can answer it.

As to the (mistaken) belief that this is polyphase, it is single phase.

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Thought I said that 

The diagram shows the white wire as the sys gr or system ground. Never confuse this with the grounding conductor.

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I was concerned about it possibly causing confusion, but opted not to confuse it further by trying to explain it. Thanks for clarifying it.

Thanks to all of you for your input.  I might be a new RV'er but I certainly know where to go for ansewers.  n a nutshell don't do it.
I'll have my electricianl install a sub-panel at the main entrance to my house (as the interior panel is nearly full).  Again, Thanks to all of you for the information.  Fred and Nit

Bravo.? ?Good answer.? ?The right way is always the best way.
;D

Q

Tom said:

Thanks Quasi.

. One reason I didn't suggest this is that, since a domestic dryer is 220V, the neutral conductor carries little or no current and, since I didn't know the applicable electrical code or how Fred's house is wired,Thought I said that?

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I have seen quite a few dryer instalations and every one I've seen all three lines were the same, That is, if one leg was 10 ga, then both the other leg and the neutral were 10 ga, no smaller wires.

Of course today there are 4 wires in the cable, all the same size, one is not insulated (or is in green depending on if it's stranded or solid wire.... Where do you find stranded? in the cord of course)

THIS DOES NOT MEAN THAT SOMEONE HAS NOT TAKEN A "SHORT CUT" IN WIREING A HOUSE, however

I've seen many-a-shortcut and I've not seen all that many houses... I'm having one house re-wired just now because the number of shortcuts, quite frankly, scares me and has for years... Now I can do something about it.