Buried Wiring for a Permanent RV Hookup


Old 10-31-09, 09:34 PM
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Buried Wiring for a Permanent RV Hookup

I have some ranch property with an 100 amp panel for my well. Sitting about 125 ft from the well is my travel trailer, which has a 110v 30 amp RV plug. I want to trench and run buried conduit with THWN wire (by my calculations, two #6 wires [1 black and 1 white] and a #10 green wire for ground). I think 3/4" conduit will work, but plan to run 1" to be safe. I will use sweeps at each end and at the trailer end, will run it from a 30 amp breaker in the box to a weatherproof 30 amp RV receptacle box at the trailer end.
Several questions:
1. for 30 amp service, are my wire sizes for 125' run correct?
2. Is the conduit size OK?
3. What kind of conduit? EMT? DB conduit? plain ole PVC? Schedule 40? 80?
4. I've read that nowadays, THHN is made to substitute for THWN (dual purpose) - true?
5. From what I've read, I assume separate THWN wires are better than running indoor Romex inside the PVC - true?
6. I plan to run two more PVC pipes in the same trench - one for water supply and one for telephone/intercom - OK?
7. What have I not considered?
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Old 11-01-09, 04:02 AM
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Welcome to the forums! As with any project of this type, especially in California, check with the local code people to get their blessings first.
First, you probably don't have a neutral at your well pump location, if that is where you planned on running the wires from. So you may be snookered from the beginning.
1) Using the #6 THWN will be adequate to prevent excessive voltage drop. #8 would be cheaper.
2) 1" conduit would be fine, larger better.
3) Use the gray pvc conduit with glued connections.
4) THWN, the "W" indicates water proof coating.
5) Romex is a bear to run in conduit and is usually not a good practice. You will thank us later.
6) Separate the conduits with dirt, put the electric at the bottom, dirt, phone, dirt, water. Again, check with local authorities, as some don't like same trench with water.
7) No neutral = no 120 volt service.
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