Multiple Motor Feeder

[Hugh W]

If you have one feeder supplying two motors one 10HP and 15HP @ 480V, so when determining the feeders you would multiply the largest motor by 1.25 and then add the other FLA for a total of 40.25A, since there is one conduit feed would you derate by .80 for more than three current carrying conductors in the raceway and figure the conductors for 50A?

 

[iwire]

I am confused, one feeder would only be three current carrying conductors.

 

[Julius Right]

I think OP means: two circuits, each supplying a single motor, in a same conduit. Then, according Table 310.15(B)(3)(a) for 4-6 conductors 0.8 it is the adjusting factor indeed.:roll:

 

[Smart $]

I think OP means: two circuits, each supplying a single motor, in a same conduit. Then, according Table 310.15(B)(3)(a) for 4-6 conductors 0.8 it is the adjusting factor indeed.:roll:

Yet if that be the case, the rest of the post makes no sense. There is no 125% largest motor factoring plus FLA of others on a single motor circuit.