What position should the Phase I switch be left in after use?

The Phase I switch should be left in the "Off position" after use to ensure safety and proper functionality of the equipment. When the switch is turned off, it prevents unnecessary power consumption and minimizes the risk of accidental operation, which is crucial in emergency response scenarios.

Leaving the switch in the off position confirms that the system is not engaged, preventing any potential hazards that could arise from an inadvertently activated system. This practice not only enhances the safety of personnel but also maintains the integrity of the equipment, ensuring it's ready for the next use without the risk of malfunction or unintended activation. Therefore, it is standard operating procedure to turn off switches after completing tasks.