When testing AFCIs, it is recommended to use the _____ on the breaker.

Using the test button on an Arc Fault Circuit Interrupter (AFCI) breaker is essential for ensuring the device is functioning correctly. The test button simulates a fault condition, allowing you to check whether the breaker will trip appropriately. This is a critical safety feature, as AFCIs are designed to prevent electrical fires that can occur from arcing conditions in wiring.

By pressing the test button, the breaker will trip if it is working as intended. This functionality ensures that the protective device can detect anomalous arcing in the circuit, thus responding to potentially hazardous electrical conditions.

Other options, like the power switch or reset button, do not perform the same testing function as the test button does. The indicator light may only show the status of the breaker but does not confirm its operational efficacy in the same way as the dedicated test feature. Hence, utilizing the test button is the recommended practice for verifying the safety and operational readiness of AFCIs.