I have an air compressor with dual 7 1/2 hp single phase 240v motors. I will have 4 conductors for the compressor (separate circuits) and a 120v lighting circuit in 1 conduit. I will need to de-rate by 80% due to 4-6 conductors in the conduit, #8 @ 90degree is 55amps by 80% is 44amps. The motor table list a 7 1/2 hp @ 40 amps is there another multiplier I have to add to the 40amps or is the #8thhn sufficient. The air compressor has a device that during each run it switches motors but in a rare case they both could run at the same time.