When should the firefighter attaching hose to the hydrant charge the supply line?

The correct answer emphasizes the importance of coordination and safety in firefighting operations. Charging the supply line should wait until the driver/operator signals for it to be done. This ensures that the proper sequence of events is maintained and prevents the potential for abrupt water flow that could lead to accidents or damage.

By waiting for the driver's signal, all personnel are aware of the timing, reducing the risk of confusion or miscommunication that could occur if a firefighter were to charge the line prematurely. This practice also allows the driver/operator to manage the water flow effectively, ensuring that the hydrant is opened correctly and safely before introducing high-pressure water into the supply line.

Charging the hose as soon as possible, before receiving the signal, could lead to unnecessary hazards and complications. Similarly, waiting until the hydrant is fully opened before charging could create a mismatch in timing and pressure, complicating the operation. Lastly, there is no need to impose a fixed time, like ten minutes, as this could be variable and depend on the circumstances present at the scene. Thus, the best practice is to charge the supply line only upon the signal from the driver/operator.