A motor switch listed as manual motor controller per UL 508 can be used as the motor branch-circuit disconnect.

A motor switch listed as manual motor controller per UL 508 can be used as the motor branch-circuit disconnect.

• A. Yes
• B. No
• C. Only for certain voltages
• D. Only if it includes a built-in overload

Answer: (B)

A manual motor controller is a control device, not a motor disconnecting means. Its job is to start and stop a motor by energizing a contactor coil (and it may include overload protection for the control or even the motor circuit, but it does not reliably isolate all current-carrying conductors of the motor branch). The motor branch-circuit disconnect is required to interrupt all conductors feeding the motor and be readily accessible, typically located at or near the motor. Because a standard manual motor controller listed under UL 508 isn’t intended to provide that complete isolation, it cannot be used as the motor branch-circuit disconnect. If a device is specifically listed and labeled as a motor disconnecting means, that would be appropriate, but a typical MMC by UL 508 is not.

A manual motor controller is a control device, not a motor disconnecting means. Its job is to start and stop a motor by energizing a contactor coil (and it may include overload protection for the control or even the motor circuit, but it does not reliably isolate all current-carrying conductors of the motor branch). The motor branch-circuit disconnect is required to interrupt all conductors feeding the motor and be readily accessible, typically located at or near the motor. Because a standard manual motor controller listed under UL 508 isn’t intended to provide that complete isolation, it cannot be used as the motor branch-circuit disconnect. If a device is specifically listed and labeled as a motor disconnecting means, that would be appropriate, but a typical MMC by UL 508 is not.