Asked in
Home Electricity
New Electrical Work
Modification of Old Electrical Work
Windows 7

What size awg do you need to install a 240v rec on a 50a breaker?


User Avatar
Wiki User
May 13, 2009 11:50PM

#8. It is better to error on the next large size. # 8 THHN 90 degree wire is rated at 45 amps. If there is a possibility that the breaker is connected to a 50 amp load the wire will be undersized. A #6 wire is rated at 65 amps. For continuous use, a load factor of 80% has to be applied. 65 x .8 = 52 amps. The only time the conductor can be smaller than the breaker size is on a motor feeder. Then the breaker is sized at 250% of the nameplate full load amps (FLA) rating of the motor. This is to allow the motor's starting current, which is about 300% FLA, to not trip the breaker on start up.