Group Motor Installations

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dvcraven052256

Member
Location
St. Louis, missouri
Occupation
Electrical Engineer
I have (3) Big Ass fan motors rated 3/4HP at 480/3 on a single 20a-3p branch circuit. I would like to feed these motors via PVC undergound conduits. My thinking is the these fan are several feet away from each other I plan to provide a wireway or junction box at the panel. See the attached sketch.

The disconnects shown will be provided at the motor.

Thanks
Dan Craven
 

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dvcraven052256 said:
I have (3) Big Ass fan motors rated 3/4HP at 480/3 on a single 20a-3p branch circuit. I would like to feed these motors via PVC undergound conduits. My thinking is the these fan are several feet away from each other I plan to provide a wireway or junction box at the panel. See the attached sketch.

The disconnects shown will be provided at the motor.

Thanks
Dan Craven
Click to expand...
Over current protection for each fan?
Do these have VFDs?
 
I see (2) potential problems.
1st, as ptonsparkey notes, how are we addressing overload protection ?
2nd, a 20 amp breaker exceeds the allowable rating for GFSC protection (430.52) for the individual motors.
 
At glace at the BA instruction manual indicates that would not meet their specs:

Dedicated Branch Circuit Protection. Each fan requires dedicated branch circuit protection
and
CAUTION: VFDs may not be daisy chained on a branch circuit without providing either one fused
disconnect or circuit breaker per controller.
The VFD does not contain individual branch circuit over-current protection. Local code and/or NEC requirements
may not permit installation of multiple VFDs on a shared feeder. Confirm prior to installation.

 
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