What size wire.

For runs of that length as someone pointed out #10 is recommended

I'd go with #8 just to play safe... And because I would rather go large than small.

REMEMBER 30 amp is 120 volt.. Just like the wall outlet.

After reading other posts from folks claiming that they do fine running their a/c on a 15 amp #14 circuit, I see no reason to spend one dollar more than what it costs for #10 wire. That is exactly what I installed and have never measured less than 117 volts (in the trailer) with a/c running.

Scott, sizing wire here is kinda like towing - Ya gotta have a dually diesel to hustle that pop up down the road. :W

joebedford wrote:
I know each leg of a 50A circuit is 120V but the voltage between them is 240V. So what do you put for voltage in this calculator? I'm guessing 120V. Makes a difference between 6ga and 4ga.

The only difference it makes is in the percent voltage drop; the absolute voltage drop is determined by ohm's law, and so depends only on the current and resistance (which, in turn, is determined by the wire size and length).

120V would seem to me to be most applicable to a 50A RV circuit, or indeed more generally to a 120/240V split phase circuit of any sort. 240V would, of course, be used for a "pure" 240V device like a welder or large air compressor.

In 30' there is NO advantage to going with anything bigger than the specified 10awg.
I have 100' of it and can run AC without ANY significant voltage drop.

pianotuna wrote:
Hi,

I would run the wire for 50 amp. I hate doing things twice.

Thanks, I already have a 50 amp on the other side of house. I just didn't want to run a 100 foot 30 amp extension around the yard. The 100 footer is just 10/2 with ground.
The new one will be on the carport side to use if I get the CP raised 18 inches.

Hi,

I would run the wire for 50 amp. I hate doing things twice.

Horizon170 wrote:
Is this what I need? It looks like it has one extra wire.
Marvin
http://www.homedepot.com/p/Southwire-50-ft-8-3-Black-Stranded-CU-SIMpull-NM-B-Wire-63949232/204765155

You would need 8-2 wire, which is actually 3 wires.

Jerry

Is this what I need? It looks like it has one extra wire.
Marvin
http://www.homedepot.com/p/Southwire-50-ft-8-3-Black-Stranded-CU-SIMpull-NM-B-Wire-63949232/204765155

I know each leg of a 50A circuit is 120V but the voltage between them is 240V. So what do you put for voltage in this calculator? I'm guessing 120V. Makes a difference between 6ga and 4ga.