430.32 Continuous-Duty Motors
|Motors with a marked service factor||125%|
|1.15 or greater Motors with a marked temperature rise 40°C or less||125%|
|All other motors||115%|
Modification of this value shall be permitted as provided in 430.32(C). For a multispeed motor, each winding connection shall be considered separately.
Where a separate motor overload device is connected so that it does not carry the total current designated on the motor nameplate, such as for wye-delta starting, the proper percentage of nameplate current applying to the selection or setting of the overload device shall be clearly designated on the equipment, or the manufacturer's selection table shall take this into account.
|Motor full-load current 9 amperes or less||170%|
|Motor full-load current from 9.1 to, and including, 20 amperes||156%|
|Motor full-load current greater than 20 amperes||140%|
If the motor current-interrupting device is separate from the motor and its control circuit is operated by a protective device integral with the motor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor.
Informational Note: Many ac motors of less than 1/20 hp, such as clock motors, series motors, and so forth, and also some larger motors such as torque motors, come within this classification. It does not include split-phase motors having automatic switches that disconnect the starting windings.
|Motors with marked service factor 1.15 or greater||140%|
|Motors with a marked temperature rise 40°C or less||140%|
|All other motors||130%|
Informational Note: A Class 20 overload relay will provide a longer motor acceleration time than a Class 10 or Class 10A overload relay. A Class 30 overload relay will provide a longer motor acceleration lime than a Class 20 overload relay. Use of a higher class overload relay may preclude the need for selection of a higher trip current.
(a) Within Sight from Controller. Overload protection shall be permitted to be furnished by the branch-circuit short-circuit and ground-fault protective device; such device, however, shall not be larger than that specified in Part IV of Article 430.
Exception: Any such motor shall be permitted on a nominal 120-volt branch circuit protected at not over 20 amperes.