Why is it crucial for motor disconnecting means to operate in all ungrounded conductors?

Ensuring that motor disconnecting means operate in all ungrounded conductors is vital primarily to prevent equipment damage during a fault. In an electrical system, when a fault occurs, such as a short circuit or an overload, it can lead to excessive currents that may damage motors, controls, and other connected equipment. If the disconnecting means only operates on some conductors and not all, it may leave certain parts of the system live and subject to damage during fault conditions.

By disconnecting all ungrounded conductors, every potential path for electricity is interrupted, thus protecting the equipment from the harmful effects of fault currents. This thorough disconnection reduces the risk of continued equipment operation under unsafe conditions, which can result in catastrophic failures or safety hazards.

The other options, while important considerations in electrical systems, do not specifically address the primary purpose of operating disconnect means in all ungrounded conductors in relation to fault protection.