JohnnyH

I want to install a 30 Amp plug on the outside of my garage to plug my fifth wheel into. I will be doing some home renovations and may be spending some time out in the RV in the yard. What gague wire and what size breaker should I be running.

Thanks
John

Fronty Owner

for 30 Amp circuits, 10 gauge is typically whats used.
To be 100% legal, you need to figure your max ambient temp and how its run (in conduit, stud wall, etc) and apply the conversion factor in the NEC to the wire temperature range your planning on using and you will see that a 80 or 95 degree 10 gauge wire will be high enough.
Also, being an outside plug, the NEC requires either a GFCI plug or breaker (I dont remember if this applys to 220 as well)
I would consider using a disconnect box near the outlet so you can turn it off while your gone. (just another level of safety).
I dont have my NEC 2005 with me, but I will try to remember to bring it home and look up some better numbers.

pappyman

I hooked up a 30 amp plugin for my RV too I used 8 ga wire ( which mite be overkill ) for the power and bought a complete RV plugin box from a camper store it came complete with breakers with a 30 amp plug and a 15 amp plug built into a weather proof box

Because I wanted it away from my house I ran everything in conduit underground to a pole with the RV electric box mounted to it

As long as I had a trench for the electric I also ran a water line to the pole

This worked out great since I can use my RV as a guest room too

spunbearing

Your numbers sound good fronty. I'm still working from a 1999 NEC( that's what they required for my ICC comb. dwelling insp. cert.) I'm not sure about the gfci on 220 either. Matter of fact I've never seen a 220v GFCI outlet or a 220v GFCI breaker. The newer gfci's ( smartlock type) won't reset with an open neutral. 220 uses 2 hot leads and a single neutral since the hots are on opposite phase. Not sure how a gfci would work with that.

dan239

JohnnyH

Do not get the idea that this 30 amp circuit for an RV is 220 volt as is being discussed in this thread. RV 30 amp receptacles are 110-120 volt. It is three wires, one hot and two grounds.

I know of one person who wired a 30 amp RV outlet 240 volt and fried some of the electrical equipment in the RV.

Make sure it is properly wired before plugging in the RV. Number 10 wire should be sufficient with a 30 amp breaker.

Daniel

spunbearing

I'm glad that you pointed that out Dan. I work on houses and have never had an RV so I assumed that they used 220v.

DSjockey

Your RV should be either 30 amp 120 or 50 amp 240, I'm guessing it's a 30 amp setup in which case you should use 10/2 romex (as long as it's not exposed to physical damage) which has 3 #10 conductors, black, white and bare, I’ll have to check my book but I believe that RV outlets are not required to be GFI as long as you use a actual RV outlet (I’ll get back today with that) if it’s surface mounted outside it needs to be in a weather proof box with a weatherproof cover

JohnnyH

Thanks for all the help. I'm glad you got me straight on the 110V thing. I sort of figured, but wasnt sure. So, use 10 gague wire to a 30 amp breaker. Does that sound right.

dan239

That is correct. I have wired up two different ones on my place with #10 wire and 30 amp breakers and that has been sufficient. The only exception I can think of is if you had a long run of wire from the breaker to the receptacle.

Daniel

Fronty Owner

110 V anywhere will not have two grounds, one ground, one neutral (which should be tied to ground at the service entrance ONLY).

I wasn't sure what RV's used, since you can get electric ranges, dryers, and other high power loads, I assumed it used 220 consting of two hots, a neutral and a ground (4 wire). from here, you can split off 2 110 V branches in the RV.

While we are talking about RV electrical (because I haven't read that section of the NEC) How are the grounding rods addressed? Do you need an 8ft rod driven into the ground near yoru recepticle to provide a solid earth ground? or is the RV treated as an appliance and uses the ground wire in the power cord?

JohnnyH

Actually I have a decent distance from the breaker to the outlet. I would guess it to be about 70'. Does that cause a problem

spunbearing

NEC 551-76 Grounding- Rec. Vehicle Site supply eq.: All electrical equipment and installations in rec vehicle parks shall be grounded as required by article 250.


Article 250 has 190 parts that covers 23 pages in the code book. Too much to post here. I would definately use a ground rod in conjunction with the wired ground and bond it to the disconnect panel.

One more note: someone suggested romex cable. Romex is not legal for use inside of a conduit and is not uv protected for exposed usage.
551-77 covers most of what you will need to know.551-80 covers the correct usage of direct burial cable.

dan239

I would not consider 70' to be a problem. If you were over 100', you might want to go to a larger wire. Plus, it is not likely you will be pulling a full 30 amps very often, if ever. If you have an RV with electric heat in the water heater, it is not a good idea to run it with the A/C at the same time because they can pull about 15 amps each and with anything else going you could be overloaded.

It is a good idea to know how many amps each item on 120 volt is pulling, so you can manage your usage accordingly to keep it under 30 amps total.

Daniel

DSjockey

Yes romex is not for inside any kind of conduit, if your running pipe you should pull in individual conductors (guess I assumed you were running in wall, attic or crawl space) 70 feet is not a problem, no ground other than the ground from the panel is required. If I was doing it for myself I would just run #12 on a 20 amp breaker with a GFI receptacle then use one of the straight blade to RV plug converters available at your RV store, this will give you 2500 watts which I would think would be adequate. It’s though to address everything here adequately, if you want PM me a phone number and I’ll call you to talk it over

rockwithjason

The 120v conversion is ok as long as you don't run the ac in the rv. The ac is the single biggest load in the rv and the cord can heat up quickly. The recepticle for the rv plug can be hard to find, you may have to do some looking around before you find one. You will need a 2 gang rain proof box and a rain proof cover. Some jurisdictions want you to have a "wet in use" cover.
You can get them at home depot or any decent supply house. No ground rod is required, if they were every rv park in the country would be illegal. The easiest way would probably be to run in the attic of the garage from the panel and pop out of the eave with a 1/2 conduit and drop straight into the 2g box. You will need to ground the box using the supplied green screw to the ground wire you will pull from the panel. You could also drill into the wall and then cut in a 2g remodel box with a rain proof cover but that can be a real pain. 220V gfci breakers are available at any home store if you find that your rv uses 220v service.