A 3Ø safety switch that is rated at 250 volts can be used for a ___ motor.

The correct response indicates that a 3Ø safety switch rated at 250 volts can be utilized for a 240-volt, 1Ø motor. This is appropriate because the voltage rating of the safety switch is higher than the operating voltage of the motor, ensuring it can handle the electrical load without risk of overheating or failure.

In the context of electrical safety and equipment ratings, it is crucial that the components match or exceed the voltage levels of the equipment they are intended to protect or control. A 250-volt rating provides a safe margin for a 240-volt application, aligning with the accepted practice of using switches rated above the nominal voltage of the motor.

While 277-volt, 1Ø could be considered because it is technically rated below the safety switch's 250-volt capability, the 250-volt rating would not adequately cover 277 volts, risking potential safety and functionality issues. Furthermore, using a 3Ø safety switch for a 3Ø motor does not apply here, as that is beyond the specifications of the switch, which is rated for lower voltage applications. Hence, the focus on the 240-volt, 1Ø motor maintains the integrity and safety of the electrical installation.