National Electrical Code Top Ten Tips: Article 440, Air Conditioning and Refrigeration Equipment

Please note, we do quote from copyrighted material. While the NFPA does allow such quotes, it does so only for the purposes of education regarding the National Electrical Code. This article is not a substitute for the NEC.

These are the 10 NEC Article 440 items we deem most important, based on the pervasiveness of confusion and the potential costs of same.

1. Article 430 also applies. You cannot apply Article 440 without also applying Article 430 [440.3].
    
2. This Article applies to air conditioning and refrigeration equipment that has a hermetic motor. For all other air conditioning and refrigeration equipment, refer to Article 442 or 424 as appropriate [440.3].
    
3. Determine the ampacity and rating of equipment per 440.6(A) and 440.6(B).
    
4. When performing calculations for multi-motor installations (meaning you will comply with 430.24, 420.53, and 430.62), you have to consider one motor to be the on with the highest rated load current. That motor is going to be whichever motor is the largest. If your two largest motors are the same size, pick either one. [440.7]
    
5. Air conditioning and refrigeration system motors are considered a single machine, even if the motors are remotely located from each other. [440.8]
    
6. When sizing the disconnects for air conditioning or refrigeration system equipment, different methods apply, depending on the type of load. The load type may be a single hermetic motor only, combination loads, or a small motor load. [440.12(A), 440.12(B), and 440.12(C).]
    
7. The rules for disconnects in 440.11 apply to every disconnecting means that is in the motor-compressor circuit between the point of attachment of the feeder and the point of connection at the motor. [440.12(D)]
    
8. Size your short-circuit and ground-fault protective devices such that they are capable of carrying the motor starting current [440.22(A) and 440.22(B)], but don't use a protective device that exceeds the manufacturer's values [440.22(C)].
    
9. When sizing the branch circuit conductors for air conditioning or refrigeration system equipment, different methods apply, depending on the type of load. The load type may be a single hermetic motor only [440.32] or combination loads [440.34 and 440.35].
    
10. You must provide separate overload protection for the motor [440.52(A)] and overcurrent protection for the conductors [440.52(B)].