peterphamee
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- Location
- Alexandria, VA
- Occupation
- General Engineer
Is it correct MCA and MOP the same if a circuit breaker feeds only 1 motor? It's understood that MOP = (largest Motor FLA x 2.25 ) + motor 2 FLA + motor 3 FLA
MCA and MOP
- Thread starter peterphamee
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Not sure where you are getting the 2.25 number,
Assuming your "MOP" term is referencing the maximum short-circuit-ground-fault protection, see 430.62.
The multiplier for the largest motor would depend on the type device used but your "formula" would be correct if the feeder protection was a circuit breaker and the actual number is 2.5 for most motors based on 430.52.
Assuming your "MOP" term is referencing the maximum short-circuit-ground-fault protection, see 430.62.
The multiplier for the largest motor would depend on the type device used but your "formula" would be correct if the feeder protection was a circuit breaker and the actual number is 2.5 for most motors based on 430.52.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Duplicate; More discussion on the subsequent thread.
Size MOP for a sngle motor
In a single 3ph motor connection, can I size the MOP by FLA X 2.25 ? It's understood MCA = FLA X 1.25
forums.mikeholt.com
MOP as defined by UL 1995 is applicable to HVAC load where there are more than 1 motor/s plus other loads (See UL 1995 Sec. 36.15). If your application is just a plain pump or fan, etc, the overcurrent protection recommended by NEC depends on the type of protection used and the type of motor/ duty it is intended for. For Induction motors being protected by Inverse time breakers, the factor is 2.5, not 2.25!
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