Load calc question for bus duct.

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oldno7

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In a machine shop, the customer has ordered a new machine (245 FLA). There is a 480V bus duct with a 600 amp feed. Do I use 220.4(A) to find the max loads already on the bus duct. There are a couple machines on it, one 200 amp whitney, 400 amp feed for a lasor machine, and welding outlets already feed from this duct. My concern is that there might be to many loads already on the bus to even add anything more.

Thanks to anyone who answers!
 
wirenut1980

wirenut1980

Senior Member
Location
Plainfield, IN
oldno7 said:
In a machine shop, the customer has ordered a new machine (245 FLA). There is a 480V bus duct with a 600 amp feed. Do I use 220.4(A) to find the max loads already on the bus duct. There are a couple machines on it, one 200 amp whitney, 400 amp feed for a lasor machine, and welding outlets already feed from this duct. My concern is that there might be to many loads already on the bus to even add anything more.

Thanks to anyone who answers!
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Are these feeds you mention for the laser and the whitney the actual full load currents, or are they protective device ratings? If there are motors involved, see 430.22, or 430.24. Otherwise I would take the full load currents of these machines, find out which ones would be operating at the same time, including any welders powered from receptacles and see what the required conductor sizes would be and what protective device would be required and match that against what you have.
 
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