I am not sure where this trend is coming from.
Yes and then when the breaker trips we can use 440.22 and charge for a service call. :grin:It could very well be a CYA for the manufacturer.
Chris
I agree with Chris but I don't understand why the nameplate doesn't allow 175%. Since the nameplate states 35 as the maximum OCP then that is what it needs to be. I have noticed more a/c units that are rating the OCPD lower than 175%-- I am not sure where this trend is coming from.
if the overcurrent protection is 35 amps, couldnt you use a40 amp breaker as the next standard size?
i was under the impression that a forty is the next standard size available, is this true?
240.6 Standard Ampere Ratings.
(A) Fuses and Fixed-Trip Circuit Breakers. The standard ampere ratings for fuses and inverse time circuit breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, and 6000 amperes. Additional standard ampere ratings for fuses shall be 1, 3, 6, 10, and 601. The use of fuses and inverse time circuit breakers with nonstandard ampere ratings shall be permitted.
Help me out here ... art. 440.22 statesDennis, the MOCP is 175% in this case. The MCA is 24.4, so full load is 19.52 (assuming a single motor-compressor.) 175% of 19.52A is 34.16A, or a 35A MOCP.
440.22 Application and Selection.
(A) Rating or Setting for Individual Motor-Compressor. The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding 175 percent of the motor-compressor rated-load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased but shall not exceed 225 percent of the motor rated-load current or branch-circuit selection current, whichever is greater.
Is not the branch circuit selection current 24.4 amps? I take this to be that 175% of the 24.4
No, 24.4 is NOT the "branch circuit selection current." Post #3 says that 24.4 is the "minimum circuit ampacity," which would be determined by 440.32 (or 440.33 or 440.34, etc.)
The branch circuit selection current is only used in specific instances and must be marked on the nameplate per 440.4(C). The way I see it, if there is not a "branch circuit selection current" marked on the unit, then it does not apply.
Is not the 24.4 amps the current we use to determine our branch circuit selection? Maybe I am confused what the branch cir. selection current is.
Is not the 24.4 amps the current we use to determine our branch circuit selection? Maybe I am confused what the branch cir. selection current is.
I agree with you Dennis.
The branch circuit selection current and minimum circuit ampacity are the same thing.
Chris