Is it permissible for the circuit breaker to be locked if it is the disconnecting means?

In fire alarm systems, the disconnecting means, such as a circuit breaker, must be easily accessible and operable in case of an emergency. Locking a circuit breaker that functions as the disconnecting means can create significant safety hazards. In situations where immediate access to the power supply is crucial, particularly during emergencies, having a locked breaker can delay response times and potentially endanger lives.

The National Electrical Code (NEC) typically requires that the disconnecting means be readily accessible. This aligns with safety practices to ensure that authorized personnel can quickly operate the breaker. Therefore, locking the circuit breaker when it's intended to be the primary disconnecting means is not permissible. This regulation underscores the importance of safety and accessibility in fire alarm systems and their associated electrical components.