correct wire size

[Al E.]

Does the code allow numer #10THHN as the branch circuit conductors for a central air conditioning unit requiring a minimum ampacity of 26 and both a minimum and maximum hacr rated overcurrent protection of 40amps? My understanding was that this would require a #8. Am I misinterpeting the code?

 

[jwelectric]

240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) or 240.4(G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied.

240.4(G) Overcurrent Protection for Specific Conductor Applications. Overcurrent protection for the specific conductors shall be permitted to be provided as referenced in Table 240.4(G).

 

[Cavie]

Does the code allow numer #10THHN as the branch circuit conductors for a central air conditioning unit requiring a minimum ampacity of 26 and both a minimum and maximum hacr rated overcurrent protection of 40amps? My understanding was that this would require a #8. Am I misinterpeting the code?

#10 ia allowed by Nameplate data and Art 440.

 

[infinity]

The MCA is used to size the conductors. #10 at 60 degrees C is good for 30 amps. If you were using NM cable even your #10 conductors on a 40 amp OCPD would be permitted.