How safe is a loco cab during a lightning storm?

NV290 wrote: The grounding wire you see connected when people are working on high voltage lines is connected to a reliable ground. The reason being if the power were inadvertantly turned on, it would instantly go through the ground wire as the path of least resistance (instead of anybody touching the wire) and then trip the circuit breaker again. If you have ever watched Amtrak or Metro North catenary workers, you will see then use grounding cable or poles that they attach right to the catenary and then the other end to the running rail.

There is another just as important reason. When adjoining conductors, say catenary on an adjacent track or transmission lines, remain energized, there will be inductive coupling that will induce a substantial voltage (and current if there is path to ground) in the conductor that is shut off to work on it. The safety ground wire shunts that induced voltage to ground avoiding the shock hazard to workers.

Ken W2KB wrote:

NV290 wrote: The grounding wire you see connected when people are working on high voltage lines is connected to a reliable ground. The reason being if the power were inadvertantly turned on, it would instantly go through the ground wire as the path of least resistance (instead of anybody touching the wire) and then trip the circuit breaker again. If you have ever watched Amtrak or Metro North catenary workers, you will see then use grounding cable or poles that they attach right to the catenary and then the other end to the running rail.

There is another just as important reason. When adjoining conductors, say catenary on an adjacent track or transmission lines, remain energized, there will be inductive coupling that will induce a substantial voltage (and current if there is path to ground) in the conductor that is shut off to work on it. The safety ground wire shunts that induced voltage to ground avoiding the shock hazard to workers.

Correct. And Insulators between sections on multi span catenary supports cannot be relied upon to provide protection. Surface contamination on insulators can allow enough voltage to flow across them to be lethal.