What is a potential issue with a tripped Closed and locked loop MCB?

The correct choice highlights that when a Closed and locked loop MCB (Miniature Circuit Breaker) has tripped, one significant issue is that no blue door lights will be active. This indicates a loss of power to the door indicator lights, which normally provide visual feedback on the operational status of the system.

In a closed and locked loop scenario, the door lights are essential for confirming whether the door can be safely accessed or if it remains locked due to operational conditions. If these lights are not active, it could lead to safety concerns, as personnel might not be aware of the actual status of the doors.

Understanding this limitation underscores the importance of monitoring indicator lights as part of operational safety procedures, especially in environments where equipment is regulated and must be interacted with carefully. The other options present different situations that can occur, but none directly address the immediate concern of having no indicator lights, which could play a critical role in determining safety and operation status.