Question on wire size for 30a

kellertx5er wrote:

NinerBikes wrote:
For runs under 50 feet, 10 gauge wire may be rated for a 30 amp load, but for continuous load, it is derated to 80% of it's value, or 24 amps. This is important to factor in if you ever decide to plug in an Electric car with an EVSE to recharge the car... your circuit is only rated 24 amps. You might want to think about future proofing your installation.

This does not apply to RV pedestals. NEC article 551.73(D) states "feeder-circuit conductors shall have an ampacity not less than the loads supplied and shall be rated not less than 30 amperes." Your RV was built with a #10 supply cord and meets the NEC, no reason a pedestal must have larger wire unless for voltage drop.

60 feet of #10 at 30 amps will drop 3.0-3.5% (3.5-4.0 volts).

You may say it doesn't apply, per NEC, but I can guarantee it, RV pedestals are being used by the electric vehicle crowd far from the inner cities in rural areas, constantly. Yes, even Tesla's plug in, when their superchargers are down, at the nearest RV park. As I said, future proof, plan ahead. Electric cars are coming, whether you like it or not, and they do need to have places to recharge.

Any electric vehicle will pull a constant long term full load for over 3 hours, through the EVSE when recharging. Which is why LADWP here in Los Angeles, who offers a rebate, is so anal about the wiring you install to a 14-50 NEMA outlet (RV outlet), and derating to 80%, so that houses and apartments don't burn down.

I didn't cut corners when I pulled 6 gauge for 50 amps, for a 14 foot run even though I get 244 volts and my e-motorwerks 40 Amp EVSE device will charge at about 10 kwh. Sure, I could have pulled 8 gauge, but I don't want to waste money buying electricity and turning it into heated wires inside my walls. All those watts used heating wire add up, if you recharge daily, and end up on your electric bill, you still pay for them, they do nothing productive for you.