over current for several motors

[stameyrh]

I have a pump, that has a 3ph 460v 15HP motor. The pump has an oil system on it. We have decided to add an oil cooler to the pump, and It comes with a 3ph 460v 3/4hp motor on it. They will both run at the same time.

I am trying to find where the code will allow me to combine the loads and use the original 15hp overloads, with adjusted settings. The code says I can use the same disconnect, circuit, starter. But I can not find if I can combine the loads on the same overloads.

 

[iwire]

Re: over current for several motors

Originally posted by stameyrh:
The code says I can use the same disconnect, circuit, starter. But I can not find if I can combine the loads on the same overloads.

You can't find it because you can not do it.

You need separate overloads for each motor.

If you combine them they will not provide overcurrent protection.

I believe the two sets of overloads could be wired in series to control one contactor so both motors shut down if either one trips it's set of OLs.

 

[kevinware]

Re: over current for several motors

I only see 430.32(A) (2005 NEC)

"Each motor used in a continuous duty application and rated more then 1hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4)"