Demand Loads for Motors

[NEC User]

I'm working on a new commercial facility (not a dwelling unit) that will have 2 large roof top units and several other large air handling units and then a lot of small motor loads. I'm trying to figure out where in the NEC it says how I can calculate demand loads for these motors.

They all won't be on at the same time. Are my supposed to calculate my demand load as 125% of the largest motor and 100% of all other motor loads? Is there a diversity factor I should use?

I tried looking at NEC 220.50 and 430.24, 430.25, and 430.26.

 

[charlie b]

What you are looking for can be found in 220.60. But I would look closely into any claim that not all motors will be running at the same time. How is that controlled? What prevents them all from running together? Is there a control device that locks out one motor if another motor is running? Absent such a control scheme, I think you will be stuck with the 125% largest plus 100% of all others.