How Long is Safe for an RV Power Extension Cord

BB_TX wrote:
Depends a lot also on what voltage you have to start with. Lot of difference if the park has 125 vac or 110 vac at the pedestal. Or somewhere in between.

This is most important. At a full 30 amps, you'll get 5% drop over 100 feet of #10. If the pedestal is at 115V, you end up with about 109V at your panel. Then you'll drop another 0.5-0.7% on the branch circuit to your A/C.