Calling an electrician

Remember, you need wire sized to match your MHs power cord. Is it 30 or 50A? Not only the refer, but converter, and everything else could get powered.

You are going to be looking at something close to #8 or #6 wire for that kind of a run unless you turn everything off and insure you don't power much more than the fridge and maybe the battery charger. If you want something close to 30AMP power at the coach I would guess at least #6 to run 150 feet.

Start with an AWG Wire Chart

Where 12 AWG is 0.00521 Ohms per Meter

That would be 0.0016 Ohms per Foot.

400 watts / 115 VAC would be about 3.5 Amps

E = I x R = 3.5 x 0.0016 = 0.0056 Volts per Foot.

On Edit: This would be for wire one way, the return drop (2 wires) would be 2 x 0.0056 = 0.011 Volts per 2 Feet.

THIS will help with your calculations....Dennis

Like the others, were I going to the labor to do this, I would run sufficient gauge to be able to run everything in the RV.

On a hot summer day when you want to spend time/work on the RV, you will be very happy with your decision to include the A/C in your amp equation.

Not an electrician....but my recommendation:

#6 copper wire will limit the voltage drop to 3.52% or less when supplying 30 amps 150 ft. on a 120 volt system.

#4 copper wire for 50 amps.

These are my rough calculations.

Executive wrote:
THIS will help with your calculations....Dennis

Dennis, this helps immensely. Thanks so much. Thank you to all the rest that have replied. We really only want to power the refer and other parasitic loads that may come on when we plug in the MH. It wil not be used to power anything else. Even the trickle chargers will not be connected when we plug in the refer preparing for a trip

The situation is similiarly to when we plug into less than 50 amp when traveling. We just limit our power usage.

Looks to me like 10 ga will allow a large safety margin.

A household 50A circuit (for a range), if new work, is identical to an RV 50A circuit: a 4 wire, 120/240V with ground, using the exact same NEMA connector and wiring.

Old 50A range installations often did eliminate the safety ground (or, perhaps more precisely, combined the neutral and safety ground into a single conductor) and this is still found and legal in existing homes, but is not used for new installations.

There's no way to plug a 50A RV cord into a 3 wire range outlet, it just won't fit. There's no harm in plugging a 50A RV cord into a 4 wire range outlet, as it's exactly the same thing electrically.

The more common problem is with 30A RV receptacles, which are superficially similar looking to older 30A 240V three wire dryer receptacles, but are not 240V connections; interchanging the two (either physically or through carelessness or cluelessness in wiring) will indeed cause problems for the RV when it gets 240V.

To the OP: The minimum circuit size that you can generally install per electric code would be a 15A circuit, with wire sized for a 15A load (minimum of 14 gauge, probably larger given the long run). Even though you may not ever use it for more than a few amps, the circuit needs to be sized for the outlet etc. Often the cost of the wire is relatively a small part of the cost of the installation (labor and conduit or whatever is not inexpensive), so the difference in cost between a proper 50A RV circuit and a 15A one may not be too great, and obviously the utility of the larger circuit is larger.

We all like to baby our toys, but come'on ???
#4 wire for running fridge and battery charger?
Those things are design to take voltage drops and I bet you will find lot of campgrounds with much lower voltage than in your case #12 wire will have.
Since you are going to put lot of labor to dig trench, run a conduit, I would put #10 wire so if in the future you want to ran 2 AC you will not have to do the job again, but come'on.

donn0128 wrote:
Remember, you need wire sized to match your MHs power cord. Is it 30 or 50A? Not only the refer, but converter, and everything else could get powered.

Not necessarily, just put in a breaker in the panel to match the wire size and load. 12 gauge 15 or 20 amp and 20 or 30 amp for 10 gauge. For 15 amp use a 15 amp receptacle, for 12 gauge 20 amp a 20 amp receptacle for 10guage a 30 amp RV receptacle.