If the pantograph or third rail shoe cannot be retracted, the Main Circuit Breaker on the train must be opened and tagged.

• A. Open and tag the Main Circuit Breaker.
• B. Leave the MCB closed.
• C. Disconnect the pantograph.
• D. Notify control only.

Answer: (A)

When a pantograph or third-rail shoe cannot be retracted, cutting power to the traction system is the first safety step to prevent hazardous contact. Opening the Main Circuit Breaker disconnects the traction circuit, stopping current flow to the pantograph path, and tagging the breaker communicates that maintenance is underway and that the circuit must not be re-energized. This combination provides both electrical isolation and a visible warning, aligning with lockout/tagout practices to protect personnel. Leaving the breaker closed keeps the system energized and dangerous. Simply disconnecting the pantograph or just notifying control does not eliminate the live electrical hazard or ensure proper safety documentation.