20 & 30hp 460V wire sizing
20 & 30hp 460V wire sizing
(OP)
I need a little help with my wire and conduit sizing. I have a 30 & 20 hp 460V motors close to each other and wish to run the wires in the same conduit. Both motors are less than 30ft from the starter (20hp) and VFD (30hp). Would a #8 and #10 wire be the correct size for the 30hp and 20hp, and they can be ran together in a 1 1/2" conduit?





RE: 20 & 30hp 460V wire sizing
If you are in the US: Check NEC Article 310 for the required derating, and size each conductor for 125% of the motor full load amps in NEC Article 430, after applying the de-rating factor.
Then size your conduit for maximum fill of 40%.
Don't forget the ground wires.
RE: 20 & 30hp 460V wire sizing
RE: 20 & 30hp 460V wire sizing
RE: 20 & 30hp 460V wire sizing
RE: 20 & 30hp 460V wire sizing
RE: 20 & 30hp 460V wire sizing
RE: 20 & 30hp 460V wire sizing
If you want to post how you came up with your numbers, we can give you some additional help.
Cheers,
Dave
RE: 20 & 30hp 460V wire sizing
20hp at 27FLA so 125% gives 34Amps
AWG #3 THHN is 110 Amps
AWG #8 THHN is 40 Amps (but according to the astric it can only be 30 Amps)
AWG #6 THHN is 55 Amps
So looking back over everything you are right the 10 would be to small, so it looks like #3 and #8. And if I pull (4) #3 and (4) #8 @ 40% fill then I will need 1 1/4" Conduit.
RE: 20 & 30hp 460V wire sizing