What is NOT considered part of a conductor's essential daily equipment?

The correct answer identifies the drum switch key as not being part of a conductor's essential daily equipment. In the context of railroad operations, essential daily equipment for conductors typically includes items that are critical for ensuring safety, effective communication, and the overall efficiency of train operations.

An emergency handbook is crucial as it provides vital information and procedures to follow in case of emergencies, ensuring that conductors are prepared for unexpected situations. Signal flags are commonly used to communicate with other crew members or to signal trains, making them a necessary tool for daily operations. Personal protective equipment is also essential for ensuring the safety of conductors while they are performing their duties, especially in environments where they may be exposed to hazards.

On the other hand, the drum switch key pertains more to specific equipment used in certain operational contexts rather than being a fundamental daily requirement for every conductor. It is not universally needed for the conduct of standard duties, which makes it less essential when compared to the other items listed.