We have installed a new 400 amp single phase service to a small water pumping station. From the service we have 2-200 amp fused disconnects protected by 175amp breakers. From the load side of the disconnects we are feeding 2 variable speed drives, the problem is I cannot fit the 2/0 wire into the drive input terminals to my satisfaction. I want to run 2 conductors in parallel to each input. Question is #1 or #2 awg.
parallel single phase
- Thread starter sgroats
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Re: parallel single phase
You can't parallel conductors smaller than 1/0 per 310.4.
If the breaker is 175 amps, and only feeds a motor, you could probably reduce the wire to a single #1 or #2 depending on the size of the motor.
For a motor, the wire doesn't have to have the same ampactiy as the breaker.
Steve
[ July 20, 2005, 09:17 AM: Message edited by: steve66 ]
You can't parallel conductors smaller than 1/0 per 310.4.
If the breaker is 175 amps, and only feeds a motor, you could probably reduce the wire to a single #1 or #2 depending on the size of the motor.
For a motor, the wire doesn't have to have the same ampactiy as the breaker.
Steve
[ July 20, 2005, 09:17 AM: Message edited by: steve66 ]
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
Re: parallel single phase
I concur with Steve.
Check 430 and the nameplate to see what size conductor you truly need. It may be that you only need #1 or #2. That may help.
I concur with Steve.
Check 430 and the nameplate to see what size conductor you truly need. It may be that you only need #1 or #2. That may help.
- Location
- Massachusetts
Re: parallel single phase
There are a couple of problems I see.
1)As has been stated you can not parallel conductors smaller than 1/0.
2)VFDs, these throw a major wrench in your plans. The feeder to a VFD must be sized based on the input current marked on the VFD regardless of the motor size. 430.2
Use a 25 HP VFD for a 5 HP motor and you still feed the VFD like it was running a 25 HP motor.
There are a couple of problems I see.
1)As has been stated you can not parallel conductors smaller than 1/0.
2)VFDs, these throw a major wrench in your plans. The feeder to a VFD must be sized based on the input current marked on the VFD regardless of the motor size. 430.2
Use a 25 HP VFD for a 5 HP motor and you still feed the VFD like it was running a 25 HP motor.
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