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Old 06-27-2012, 09:18 PM   #1
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1970 31' Sovereign
Burnsville , North Carolina
Join Date: Dec 2011
Posts: 57
How do I wire AS for an RV hook-up that is 75' away?

Hello out there!
I am about to move my 1970 Sovereign to its more or less permanent parking spot. It's a 30amp system and we will not be using the air conditioner. The RV plug-in box is 75 feet away. I want to replace the old power cord which is only about 20 feet long. Any advise on what gauge wire i need to use to go 75 feet? Also, I have installed a new electric-only H20 heater and am planning on hooking it up to a switch inside the AS and then running a 75' cord to the RV plug-in. Same question here as far as wire gauge. Have any of you replaced the old breaker box in the AS to accommodate a separate circuit for your H20 heater?
Thanks in advance for any help you can give. I have done most of the rehab on this unit myself but don't know much about electricity.

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Old 06-27-2012, 09:31 PM   #2
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Old 06-27-2012, 09:57 PM   #3
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You can check with any electrical supply house on the size of the wire. If your heater is close to 20 amps would assume at least a #10 wire.

Keep in mind that the wire size will have to go all the way back to your panel in the house.
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Old 06-28-2012, 03:25 PM   #4
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South of the river , Minnesota
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10 gauge will work especially if you are not using the air conditioner. There will be some voltage drop when heavy loads are present.

I have a 6 gauge 60' cord that I sometimes use. Works great but it is heavy and awkward. I salvaged it from a silo unloader at a farm. To purchase a cable like that new would be prohibitively expensive with today's copper prices.

If you are parking permanently you're better off moving the power to a closer location and burying the wire. Then it only has to be done once. The flexible cable will only last a few years in the sun while buried type UF cable will last 50 years or more.
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Old 06-28-2012, 03:33 PM   #5
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1976 Argosy 28
Milton , Ontario
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Hi Bill,

Jammer is right on, by mentioning trenching in a new line.

You would not be happy of feel safe by running large gauge extention cord(s) along the ground. After all someone might mistakenly cut into the cable and electrocute themselves.

I'm all for burying it the 75'.

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Old 06-28-2012, 04:34 PM   #6
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If you are sure you not going to move the trailer, I would suggest that you bury the proper size cable and hard wire it into the box on the trailer. If you don't want to do that you can buy a box like they use in campgrounds (Home Depot has them) and set it up close to the trailer. The cover will protect the plug from the elements.
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Old 06-29-2012, 08:51 AM   #7
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1970 31' Sovereign
Burnsville , North Carolina
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As usual, the forum is very helpful. Thanks for that input. The problem I have with trenching is that I live in the mountains and am likely to run into solid rock. When our underground power was put in, they had to blast through several feet. So, that's why i am thinking of going above ground. The actual distance is closer to 75' and I am think of suspending the cable off the ground with some small poles and marking it well so no one will trip. Do you guys think 10 gauge is okay? Thanks. -Bill
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Old 06-29-2012, 09:41 AM   #8
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Can you run the cable through plastic pipe to protect it? Jim
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Old 07-01-2012, 10:43 AM   #9
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Palo Alto , California
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I second the above recommendations- run the supply line to a location close to your trailer either through direct burial cable, or if that is impossible run through PVC conduit either below or above ground. Home depot has all the materials you need to do this and it's an easy project.

The key thing is you want to protect your supply cable from getting damaged - either from animal chewing, sun/weather, or any other accidental damage. You don't want to wake up to fried raccoon or dog one morning from them chewing through your cable.

Last - to your original question - three conductors of 10-gauge wire is absolutely adequate for a 30 amp circuit running 75 feet - you need hot, neutral and ground conductors, and for simplicity of discussion you should get 10 gauge for each of them. Assuming you run your cable in conduit, I would use 2 inch schedule 40 PVC conduit - underground is better, but above ground is ok.

You will experience an approximately 5 volt drop in voltage over 75 feet using 10 gauge conductors - which means it's probably ok to run your AC if you have adequate voltage where you are starting your run.
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Old 07-02-2012, 03:42 PM   #10
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1970 31' Sovereign
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So, what about using 8gauge wire instead?
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Old 07-02-2012, 03:52 PM   #11
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8 gauge will work.

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