Which of the following is NOT a characteristic of lockable disconnecting means?

The characteristic indicating that a lockable disconnecting means "must remain locked when closed" is indeed not a requirement inherent to the definition of such devices as per the National Electrical Code. Lockable disconnecting means are designed to be used in a manner that allows them to be locked in an "open" position to ensure safety during maintenance or repair activities. This characteristic is crucial as it helps prevent accidental energization of the circuit while work is being performed.

The other characteristics align well with the NEC's guidelines. Devices designed for lockable disconnecting means should be capable of being locked open, ensuring that they can be safely secured during maintenance. Additionally, they should allow for permanent locking, which means the lock can be applied in such a way that the device remains open and safe for as long as necessary during work. Lastly, retaining the locking mechanism functionality is essential, as it guarantees that the user can effectively utilize the lock system to enhance safety.

Overall, while safety and operational integrity of these devices are of utmost importance, the stipulation that they "must remain locked when closed" does not reflect the functionality or requirements established for lockable disconnecting means in the NEC.