430.24 + 621.14 - elevator motor feeder sizing

Location
TX, USA
I hope this is a simple question on the approach to elevator motor feeder sizing.

Does one combine the effects of 430.24 (motor feeder circuit = 125% of the largest motor current + sum of other motor currents) with 621.14 (demand factor for elevators).

E.g., so if I have 5 elevators that have currents 20, 10, 5, 5, 3... I'd end up with : 82% * (20 * 125% + 10 + 5 + 5 + 3).

Thx
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
That is my understanding on how it is done. 125% of the largest plus the sum of the other motors. Then, of course, there is a demand factor for 5 elevators of 82%.

Looks like you have it right.
 
Location
TX, USA
The example D10 in the Annex does NOT apply a 125% to the 133A elevator motor.. it only applies 125% for the continuous controller loads. Perhaps it is simply that Elevators aren't considered as part of the 'largest motor' provision of 430.24? Can anyone clarify?
 
Location
TX, USA
upon re-review of the code... 620.14 seems to be an optional (permitted) way to determine feeder demand vs. what is stated in 620.13.
620.13 basically referrs to 430.24... 125% largest motor + sum of rest. So, It seems to me one does one or the other, but not some means of combining the two. Though, I guess if the AHJ says otherwise, you do that!
 
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