Residential ac consensor calls for max fuse/breaker?

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The condensor should also have a "minimum circuit ampacity" listed on the nameplate. If # 12 is large enough to satisfy the min. cir. amp., then yes.
 
As JLJ stated the conductors are sized to the MCA and the next size up rule does not apply. The MaxOCPD is not relevant to sizing the conductors.
 
Jerseydaze said:
I know this is the rule but what protects the wire from over current?
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The overload protection required by 440.52, often integral with the unit, protects the conductor from overload. The OCPD protects against short circuit and fault.
 
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infinity said:
As JLJ stated the conductors are sized to the MCA and the next size up rule does not apply. The MaxOCPD is not relevant to sizing the conductors.
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True, I might add that if the MOCP is 25 amp, it is possible that the MCA could be low enough that even #14 could be used, even at the 60 degree rating.
Note to the O.P., as others said, the key for conductor sizing in this application is the MCA value. It already has everything figured into it, including the 125%, so you can simply select the conductor size based on the ampacity table using the MCA. Of course you have to be compliant with any ampacity adjustments and terminal temperature.
For example, you could use #14 NM cable for a unit with an MCA of 14.9 and a breaker of 25 amp (if that is the MOCP stated on the data plate. For what it is worth, I've seen more than 1 inspector that does not understand this.
 
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