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Old 05-14-2013, 02:48 PM   #1
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underground wire

I have a travel trailer about 400ft behind my house want to run power to it anyone have any idea on what I need to do.tks Jim


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Old 05-14-2013, 03:42 PM   #2
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underground wire

If you will use up to 20 amps at 120 volts in the trailer you will need to run #4 gauge copper (or 2 gauge aluminum) wiring down to the trailer. The wiring must be waterproof e.g. UF style cable or THWN style single conductors, the latter must be enclosed in a conduit. At each end a foot or two of 12 gauge wire can be spliced on to fit the terminals of receptacles, 20 amp breaker, etc.

Any chance you can keep the trailer closer to the house?

Allowing 3-1/2 percent voltage drop (4 volts lost) at 120 volts and 20 amperes the round trip can have at most 1/5 ohm of resistance. Most travel trailers and recreational vehicles can be plugged in to an ordinary (20 ampere) circuit at a house or campsite; some really want a 30 amp circuit and come with a cord adapter for a 20 amp circuit.

In any portion of a circuit including the wiring, the number of volts (not the percentage) dissipated or consumed or lost is at all times equal to the number of amperes flowing through times the resistance of that portion.

We chose 3-1/2 percent as the allowable voltage drop here because from time to time there may be additional voltage drop upstream of the panel depending on total current draw and we really want the grand total to be less than 6 percent.


Do you get coverage you can count on? From the bag of fertilizer? From your lawn sprinklers?

Last edited by AllanJ; 05-14-2013 at 04:02 PM.
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Old 05-14-2013, 03:48 PM   #3
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underground wire

120v at 30 amp 400 ft will require #1 copper at 2.9% VD
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Old 05-14-2013, 07:23 PM   #4
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underground wire

The utility company allows wider ranges of voltage fluctuation than you guys provide...
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