A/C & Refrig Ampacity ?

[MikEE]

Hello,

Have a question regarding calculating branch circuit conductor ampacity for A/C Units.

NEC 440.32 Single Motor-Compressor
"... 125% of either the motor compressor rated load current or the branch circuit selection current ..."

However, NEC 440.6 does seem to say use nameplate values directly.

Do I use the nameplate values directly or bump them up to 125% when calculating branch circuit conductor ampacity?

Thanks,
Mike
Hibbing, MN

 

[infinity]

You are required to use the nameplate. The Minimum Circuit Ampacity is used to size the conductors. The Maximum Fuse or CB is used to size the OCPD. Also the limitations of 240.4(D) do not apply so for example a unit with an MCA of 19 amps could be fed with #14 THHN according to 310.16.

 

[finhead]

You are required to use the nameplate. The Minimum Circuit Ampacity is used to size the conductors. The Maximum Fuse or CB is used to size the OCPD. Also the limitations of 240.4(D) do not apply so for example a unit with an MCA of 19 amps could be fed with #14 THHN according to 310.16.

Trevor
I agree with you provided the AC unit is multimotor or combination load as detailed in 440.35. I can't imagine an AC unit without a compressor and a fan motor.
A similar question posted nearby related to a test question stating only one harmetic refrigerant motor compressor. In that case it was necessary to multiply the MCA by 125%