What must a motor's disconnecting means accomplish?

The correct answer emphasizes that a motor's disconnecting means must be capable of disconnecting the motor from all ungrounded circuit conductors. This is crucial for safety and maintenance purposes, ensuring that when the motor is being serviced, there is no possibility of an electrical shock from any sources of power that may still be present. Disconnecting from all ungrounded conductors means that all phases of electrical supply to the motor are interrupted, which is essential to provide a safe working environment.

When a motor disconnects only from the main power supply, it does not guarantee that the motor is entirely de-energized, as there may still be ungrounded conductors that could pose a risk during maintenance. Reducing the load on the circuit does not ensure safety in terms of electrical disconnection. While allowing safe access for maintenance is important, the primary function of the disconnecting means is to ensure the motor is completely disconnected from electricity to prevent accidents or injuries. Thus, the effective disconnection from all ungrounded circuit conductors fulfills both safety and operational standards required in electrical systems.