Feeder Calculation

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Canton

Senior Member
Location
Virginia
Occupation
Electrician
I have a feeder calculation that I have to do. It will have (1) 10HP and (1) 5 HP motor, split unit A/C, Lighting, and general receptacles. The motors and lighting are continous, everything else is not.

Should the calculation be 125% of the continuous plus 100% of the non-continuos?

Or does 430.24 come into play for the feeder? Only the largest motor is 125%, the other is 100% (even though continuous), then the non motor continuous loads at 125%, and non motor non continuous loads at 100%?

When is a feeder calculation done with all continuous loads calculated at 125%, even when there is motor loads? 430.24 throws me off.
 
I would calculate the largest motor at 125% and the other motor at 100%
You need to look at art. 220 also for demand factor Lighting and receptacles
 
Dennis Alwon said:
I would calculate the largest motor at 125% and the other motor at 100%
You need to look at art. 220 also for demand factor Lighting and receptacles
Click to expand...

This is in an industrial environment in a room that will have a sub panel for the rooms equipment. Required receptacles and lighting demand factors won't be applicable here.
 
If you are having to competitive bid the job then I'd follow 430.24, 125% of largest + 125% continuous and 100% of the other motor and non-continuous.
I've not seen many industrial situations where they are interested in "minimum". 430.63 is going to dictate a fairly large over-current device due to the motor load and, if it's a normal industrial setting, it is likely in the future they will assume the allowable load based on the breaker so I would be tempted to install a feeder based on the OCP device not the calculated load more often than not the load will be increased over time.
 
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