10 awg wire on 50A breaker

[jar546]

Is it possible that this is actually allowed and is compliant? If so, under what circumstances can we have a 10 awg wire on a 50A breaker?

 

[steveray]

A/C condenser...

 

[jar546]

A/C condenser...

yes, that is absolutely one possibility. Good answer. It is possible that the data plate on the condenser said: Min Circuit Ampacity 28.7A and Maximum Overcurrent Protection 50A. (fused or CB)

 

[BLangley]

I know enough to troubleshoot basic stuff and to also know I'll probably kill myself if I ever poke around a 3-phase system.

Assuming the condenser example- if 10 awg wire can carry 40 amps (at 90 degrees C per Wikipedia chart on AWG), wouldn't the wire be a fire risk if it actually pulled 50 amps? Or would the disconnect at the condenser be fused lower and all is right and compliant?

 

[jar546]

I know enough to troubleshoot basic stuff and to also know I'll probably kill myself if I ever poke around a 3-phase system.

Assuming the condenser example- if 10 awg wire can carry 40 amps (at 90 degrees C per Wikipedia chart on AWG), wouldn't the wire be a fire risk if it actually pulled 50 amps? Or would the disconnect at the condenser be fused lower and all is right and compliant?

Great question. Actually, #10 copper is only good for 30A. You can only use the 90deg column in certain circumstances. For motors, in most cases, the circuit breaker is only used for short circuits and ground faults and would trip. The real issue with wire size vs breaker is the ability of the wire to handle normal loads.

You may want to see the thread I posted about circuits for motors. You can click here: https://www.thebuildingcodeforum.co...ductors-and-overload-short-circuit-gfp.26518/