Instantaneous-trip circuit breakers can be installed ___.

Instantaneous-trip circuit breakers can be installed ___.

• A. as a branch-circuit OCPD for lighting
• B. as a part of listed combination with a motor controller
• C. either a or b
• D. neither a nor b

Answer: (B)

Instantaneous-trip protection is intended to respond immediately to a short-circuit, but for motor circuits the protection must come as a listed combination with the motor controller. That ensures proper coordination between the short-circuit protection and the motor’s starting and overload protection, and it is specifically tested and approved for that use. Using an instantaneous-trip breaker on a lighting branch circuit isn’t permitted because it isn’t part of a listed motor-controller assembly and wouldn’t meet listing/coordination requirements. So the only appropriate installation is as part of a listed combination with a motor controller.

Instantaneous-trip protection is intended to respond immediately to a short-circuit, but for motor circuits the protection must come as a listed combination with the motor controller. That ensures proper coordination between the short-circuit protection and the motor’s starting and overload protection, and it is specifically tested and approved for that use. Using an instantaneous-trip breaker on a lighting branch circuit isn’t permitted because it isn’t part of a listed motor-controller assembly and wouldn’t meet listing/coordination requirements. So the only appropriate installation is as part of a listed combination with a motor controller.