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First of all, this is my first post and thanks for allowing me to join.

I have a travel trailer that I want to get a proper power hookup for on my property. The trailer has a120v 30amp shore power connection (plug) on it. I have already run a 10/3 line from the main panel in the garage to the pole where I want to trailer power to go.

Why 10/3? good question we're very rural and when friends visit they my also bring thier travel trailer, so I figured I'd put 2 30amp hookup and there lies my first question. I originally planned to put a 240v double pole breaker in the panel and take that and a neutral to the pole where one line and the neutral would go to one 30amp 120v receptical and the other line and the neutral would go to a second 30amp 120v receptical. although I doubt these would be used very frequently at the same time the possibility is there and I wanted to confirm that the neutral would be large enough for this at 10awg. I understand as this is alternating current it shouldn't matter but was hoping to confirm that.

Also, as the buried line from the garage to the pole is approx. 110' do I have to or should I put a outdoor subpanel on the pole with 2 120v 30amp breakers before the recepticals?

Thanks in advance for any and all suggestions.

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  • Is the breaker GFCI type?
    – Ecnerwal
    Commented Jul 20, 2021 at 0:43
  • the 240v breaker at the panel I was planning to use isn't currently.
    – mtb76
    Commented Jul 20, 2021 at 1:00
  • See also this discussion. Commented Jul 20, 2021 at 5:27

2 Answers 2

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10/3 as the basic size is correct for 30A, and you are correct about double breaker, 2 x 30A 120V, etc. But there are some potential complications:

  • GFCI

As already noted in a comment, you will need to have GFCI. For a bunch of reasons, the best way to do is probably going to be a breaker that has GFCI built in. For a simple 15A or 20A 120V circuit there are more options - 30A MWBC (that's 240V feeding two 120V) gets a bit more complicated.

  • Cable/Wire Type

You can't take standard indoor NM cable (a.k.a., Romex) and bury it. You need cable that is properly rated for wet/outdoor/buried use. If you already have the right type of cable, great. Just noticed (because of Machavity's answer) that you already ran the cable. Based on that, if you ran it right (24" deep, UF-B cable), leave it as is. If not, you should seriously consider conduit. That may cost more initially, but if you oversize it a bit (not too much) then you will have future options (e.g., if you want to bump up to 50A or more using bigger wire). And even for 30A right now, you may find that you can get aluminum wire instead of copper and have more capacity right away for the same price as 10 AWG copper. Plus conduit (varies depending on type) does not have to be buried as deep as cable. Note that with conduit you use individual wires rather than a preassembled cable.

  • Cutoff Switch, Subpanel, etc.

You may need (I'm not 100% certain) a cutoff switch at the outdoor location. You definitely will if you put in a subpanel, but with a subpanel you can install a main breaker in the subpanel (>= the breaker in the main panel feeding the subpanel) and use that as a cutoff switch.

If you use a subpanel then you will also need separate ground rods. I am pretty sure that is not required if you simply have "1 circuit". (An MWBC counts as 1 circuit.)

  • RV Panel

A standard RV Panel:

RV Panel

includes a 240V 50A, 120V 30A (which is what you need right now) and a 120V 20A receptacle (a.k.a., "ordinary receptacle"). That is a standard combination to allow "almost anyone" to connect. However, it doesn't (not directly anyway) provide "2 x 30A". But it may be worth considering as a nice packaged solution.

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This isn't too hard, since you got the biggest part right

The good news is that you got the biggest part of the problem right with your choice of a 10/3 PVC-jacketed MC cable for the run. From there, you can fit an all-in-one RV pedestal with 2 30A and 2 20A receptacles in it, such as the Midwest U131CP6010 or U041GB6, at the destination. This works because the 551.73 RV park load calculations only count the load from the largest receptacle at a given pad, so the 20A receptacles are "free".

Note that you'll need to use some chunky wirenuts to pigtail the 10AWG in your cable up to 6AWG to make it fit the lugs on the posts in question. You may also need to use a "redhead" bushing at the cable end, as pedestals of this style are designed to work with multiplex (URD/USE) type direct buried cables and thus lack knockouts at the bottom that you could attach a MC fitting to.

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