time.

440.35 Multimotor and Combination-Load Equipment.

The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment in accordance with 440.4(B).

V. Controllers for Motor-Compressors

440.41 Rating.

(A) Motor-Compressor Controller. A motor-compressor controller shall have both a continuous-duty full-load current rating and a locked-rotor current rating not less than the nameplate rated-load current or branch-circuit selection current, whichever is greater, and locked-rotor current, respectively, of the compressor. In case the motor controller is rated in horsepower but is without one or both of the foregoing current ratings, equivalent currents shall be determined from the ratings as

follows. Table 430.248, Table 430.249, and Table
430.250 shall be used to determine the equivalent full- load current rating. Table 430.251(A) and Table 430.251 (B) shall be used to determine the equivalent locked- rotor current ratings.

(B) Controller Serving More Than One Load. A control- ler serving more than one motor-compressor or a motor-compressor and other loads shall have a continuous-duty full-load current rating and a locked- rotor current rating not less than the combined load as determined in accordance with 440.12(B).

VI. Motor-Compressor and Branch-Circuit Overload

Protection

440.51 General. The provisions of Part VI specify devices intended to protect the motor-compressor, the motor- control apparatus, and the branch-circuit conductors against excessive heating due to motor overload and failure to start.

FPN: See 240.4(G) for application of Parts HI and VI of
Article 440.

440.52 Application and Selection.

(A) Protection of Motor-Compressor. Each motor- compressor shall be protected against overload and failure to start by one of the following means:

(1) A separate overload relay that is responsive to motor-compressor current. This device shall be selected to trip at not more than 140 percent of the motor- compressor rated-load current.

(2) A thermal protector integral with the motor-com- pressor, approved for use with the motor-compressor that it protects on the basis that it will prevent danger- ous overheating of the motor-compressor due to over- load and failure to start. If the current-interrupting de- vice is separate from the motor-compressor and its control circuit is operated by a protective device inte- gral with the motor-compressor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor.

(3) A fuse or inverse time circuit breaker responsive to motor current, which shall also be permitted to serve as the branch-circuit short-circuit and ground-fault protec- tive device. This device shall be rated at not more than

125 percent of the motor-compressor rated-load cur- rent. It shall have sufficient time delay to permit the motor-compressor to start and accelerate its load. The equipment or the motor-compressor shall be marked with this maximum branch-circuit fuse or inverse time circuit breaker rating.

(4) A protective system, furnished or specified and ap- proved for use with the motor-compressor that it pro- tects on the basis that it will prevent dangerous over- heating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and