A 120-volt motor would require a starter with a minimum of how many power pole(s) to open the motor circuit?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (A)

For a 120-volt motor, a starter with a minimum of one power pole is necessary to open the motor circuit. Power poles in a starter are designed to control the electric supply to the motor. In this scenario, a single power pole can adequately disconnect one line of the 120-volt supply, which is essential for providing an off switch to ensure safety when servicing or stopping the motor.

In North America, typical single-phase motors operate on a two-wire system that carries 120 volts. A single pole is sufficient to interrupt this circuit, making it unnecessary to have multiple poles for a basic motor application. Multiple poles would be required in setups where higher voltages or three-phase systems are involved, where more complex switching is needed to ensure balanced load management and safety, but for a straightforward 120-volt motor, one pole is suitable.