A.C load

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Toros

Senior Member
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Tujunga, CA
Hi
I have to provide power to (5) 7- ton @ 3ph, 240v air handling units

i think each AC input is 30A
so, I would provide 200A panel @ 110/240v 3ph delta thru 3/0 THHN,CU set

what do you think???
 
Will all be running at the same time?

Is 30 the FLC or the max OCPD?
 
I think that you first need to actually look at the nameplate to find the Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection ampacity.
Then using the MCA you look at how many units will be connected to each phase conductor and find the vector sum of those currents in that line wire. That will tell you what size breaker and feeder you need. If it is likely that all five units will try to start st the same time, the NEC does not care but from a design view you may want to upsize things.
 
GoldDigger said:
I think that you first need to actually look at the nameplate to find the Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection ampacity.
Then using the MCA you look at how many units will be connected to each phase conductor and find the vector sum of those currents in that line wire. That will tell you what size breaker and feeder you need. If it is likely that all five units will try to start st the same time, the NEC does not care but from a design view you may want to upsize things.
Click to expand...
Will this be the only load on the panel?
Is the 120/240 four wire the only service available, and are the units rated for connection to a high leg 208 volts above ground?
You may need to connect them all to the A-C phase otherwise.
 
GoldDigger said:
Will this be the only load on the panel?
Is the 120/240 four wire the only service available, and are the units rated for connection to a high leg 208 volts above ground?
You may need to connect them all to the A-C phase otherwise.
Click to expand...

OP said the units were 3? and the high leg would make no difference in that case.
 
Toros said:
Hi
I have to provide power to (5) 7- ton @ 3ph, 240v air handling units

i think each AC input is 30A
so, I would provide 200A panel @ 110/240v 3ph delta thru 3/0 THHN,CU set

what do you think???
Click to expand...


This is is a church, meeting place, civic

and all units run simultain.
@ 30 FLA per nameplates
 
Little Bill said:
OP said the units were 3? and the high leg would make no difference in that case.
Click to expand...
The high leg would possibly make no difference if the AHU's do not use a neutral (which the OP did not explicitly state) but just the same, the voltage to ground from the high leg will be greater than it would be on a 240Y/138 supply. If the AHU is rated for use on a 240V corner grounded delta, then there should be no problem with a high leg instead.
 
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