series rating or fully rating

[Toros]

Hi, do you think I can use "Series Rating" between house/sub panel and main switch gear/breaker where one of the loads in that panel is 25 HP elevator motor or "Fully Rating" based on 21000A avail. short cir. per utility comp.??????. Thank you

 

[Jraef]

Series ratings have nothing to do with what the load is, it has to do with testing and listing by the manufacturer. You can't do it on your own, your panels 9and the breakers in them) either have it or they don't.

 

[don_resqcapt19]

(C) Motor Contribution. Series ratings shall not be used where
(1) Motors are connected on the load side of the higher-rated overcurrent device and on the line side of the lower-rated overcurrent device, and
(2) The sum of the motor full-load currents exceeds 1 percent of the interrupting rating of the lower-rated circuit
breaker.

This limitation does not appear to apply to the OPs installation as the motor is connected on the load side of the lower rated breaker.

 

[jim dungar]

This limitation does not appear to apply to the OPs installation as the motor is connected on the load side of the lower rated breaker.

There could be an issue anytime a panelboard has a motor as a load on one of its branches, as the motor is also electrically on the line side of the other branches in the panel.

The typical lower end AIC for breakers is 10k @ 240V and 14k @ 480V. So if designers always limit the total motor loading in any one panel to 100A @ 240V and 140A @ 480V, they should never have problems with motor contribution. For most installations it would be difficult to have problems with series ratings if the panel feeder is only 200A maximum.