Neither Phase one nor Phase two modes can override which function?

Neither Phase one nor Phase two modes can override which function?

• A. Elevator shutdown (shunt trip)
• B. Elevator recall
• C. Emergency stop
• D. Door interlock

Answer: (A)

In fire-service operation, Phase 1 and Phase 2 modes are designed to override normal elevator behavior to prioritize firefighter safety and access. They disable ordinary car and hall calls and control how the car responds during emergencies. But some safety features remain as hard protections that cannot be bypassed by these modes. The elevator shutdown (shunt trip) is one of those protections. It physically disconnects power to the elevator drive and related controls, causing an immediate stop regardless of the fire-service mode. This ensures the elevator cannot move in dangerous conditions, even when firefighters are operating the system. The other functions can be engaged or overridden in a controlled way during Phase 1 or Phase 2 to support firefighting operations—for example, recall can bring the car to a safe floor for firefighters, and emergency stop or door interlock actions can be used as part of safety procedures. But the shunt trip remains a non-overridable safety disconnect, making it the correct choice.

In fire-service operation, Phase 1 and Phase 2 modes are designed to override normal elevator behavior to prioritize firefighter safety and access. They disable ordinary car and hall calls and control how the car responds during emergencies. But some safety features remain as hard protections that cannot be bypassed by these modes. The elevator shutdown (shunt trip) is one of those protections. It physically disconnects power to the elevator drive and related controls, causing an immediate stop regardless of the fire-service mode. This ensures the elevator cannot move in dangerous conditions, even when firefighters are operating the system.

The other functions can be engaged or overridden in a controlled way during Phase 1 or Phase 2 to support firefighting operations—for example, recall can bring the car to a safe floor for firefighters, and emergency stop or door interlock actions can be used as part of safety procedures. But the shunt trip remains a non-overridable safety disconnect, making it the correct choice.