Can a KT_7-25S/25H/45H controller be used a branch circuit protection on non-motor or resistive loads like a heater?

Answer:

The KT_7-25S/25H/45H frame devices are UL 508 listed as a manual motor controller, a Type E manual combination motor controller (with KT7-25-TE1 or KT7-45-TE spacing adapter) or as an at motor disconnect (with lockable twist knob KT7-K*). They do not have the UL 489 listing needed to provide branch circuit protection to a resistive load.

The KT_7-25S/25H/45H frame devices are for motor and transformer loads only for UL and CSA applications.

They can be used on resistive loads for Non UL or CSA applications. They can be used on resistive loads for IEC applications because they are considered a circuit breaker in that part of the world.

If you are looking to isolate or give branch circuit protection to a resistive load, you could use a contactor plus fuses or a UL 489 listed circuit breaker to achieve the branch circuit protection.