sizing of a motor cable to iec/nema/bs standards


Thread Starter


I have a motor which will be driven from an inverter. the motor is rated for 460V, 3ph, 60Hz and the supply voltage is 480V, 3ph, 60Hz. I would like to know how to size the cable going from the motor to the inverter.

the full load current is 12.5A
the full load power factor is 0.82
it will be routed in conduit
the inverter will be roughly 30m from the motor

Bob Peterson

There are no "NEMA" standards involved. If it is a US installation, one would follow the National Electrical Code (NEC).

Without knowing more about the install my best guess would be that #14 conductors would be adequate. However, depending on the exact circumstances of the install, there is some chance they might have to be larger.

Bob Peterson

I realized I made a mistake here. Most likely for a 480V motor this would be 10HP. The charts would give you about 12 FLA. 125% of 12 A is 16 A therefore the NEC would require #12 conductors. Might be higher depending on the exact situation.