The motor overload unit for a single-phase motor fed from an ungrounded 2-wire, single-phase AC source will be placed in which conductor?

For a single-phase motor fed from an ungrounded two-wire system, the motor overload unit is placed in the phase conductor. This is essential because the phase conductor carries the current that powers the motor. Overload units are designed to detect excessive current flowing through the phase conductor, protecting the motor from overheating and potential damage.

Placing the overload unit in the phase allows it to sense any abnormal conditions that could lead to motor failure, such as excessive load or faults in the motor itself. The neutral conductor, in this case, does not carry the load current for the motor; rather, it serves as a return path for the current. Therefore, it would not be effective to monitor overload conditions if the overload unit were placed in the neutral conductor.

Using either conductor would be inappropriate since the overload protection relies on monitoring the current that actually powers the motor; thus, placing the unit in neither would omit the necessary protection altogether. Understanding the role of these conductors in a single-phase system underlines the importance of proper placement of protection devices to ensure safe and efficient operation of electrical equipment.