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Monday, August 20, 2012

120-Volt RV Shore Power at Home

I would like to install an electrical outlet at the house to plug our Class A motorhome into when it is here. I only want 30-amp service. Should I install a 30-amp, 3-wire, 120-volt outlet or a 240-volt, 30-amp outlet? Thanks! Robert, (no city/state)

Robert, many RVers still with a home base have opted to install a dedicated RV circuit so the coach can be plugged in at home. Obviously I am a fan of such modifications as long as they are installed per code and by a qualified and licensed electrician or electrical contractor.

The first step is to analyze if indeed you have the capacity to add a 30-amp circuit to your existing panelboard distribution box. Not just that you have the physical space in your panelboard to install another breaker, but rather that you have 30-amps of spare electrical capacity of service coming into the main panel at your house.

The next step would be to acquire the proper materials to add a 30-amp sub-panel and the associated wiring you will need. Unless the length of the run between the main panel and the new sub-panel location is extremely long, be sure to use 10-gauge conductors. You will be installing a 120-volt, 3-wire, 30-amp receptacle. It's also vital that the electrical service entrance at the house be equipped with a proper grounding rod.

The RV 30-amp receptacle (as pictured), is common only to the RV industry. This configuration is not used in any other application, so you may have to purchase one from a local RV service center rather than from a commercial electrical parts house. Do NOT wire two legs of 120-volts into a 240-volt configuration! Your three conductors will consist of one hot lead (black), one neutral lead (white) and one ground conductor (bare copper or green). Protect the circuit with a 30-amp circuit breaker.

I would further suggest installing a disconnect switch at the receptacle box as well; one that can be locked out when not needed. Be sure to use the appropriate tubing, conduit, 4x4 boxes, conductors, breaker and weatherproof enclosures that comply with the National Electrical Code (NEC) and any other local standards in your area.

Again, your best resource is a licensed and qualified electrician. Please notice I almost always use “licensed” and “qualified” in the same sentence when referring to electricians. It’s not a difficult task but I highly recommend having a dedicated RV receptacle at the house, especially if the electrical integrity of the other circuits in the home are unknown or dubious. As an example, some older homes may not have a neutral conductor in the existing wiring.

The optimum location for the RV receptacle is that location which does not require the use of an extension cord in order to connect the motorhome. If you must still use an extension cord, be sure that it too is rated for 30-amps of current flow or more. Use the shortest extension possible. You’ll want to avoid a coiled up 100-foot extension cord when a 20-footer would still reach. The less length, the less heat. The less heat, the less resistance. The less resistance, the less voltage drop. Obviously, less, in these instances, is better! But I do want to emphasize that this is definitely not a do-it-yourself project! Always retain the services of a professional, licensed electrician.


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