What must be done to ensure a fan is operational after an alarm condition?

To ensure a fan is operational after an alarm condition, it typically requires manual intervention, such as restarting it from a separate button or key switch. This is largely because, in many fire alarm systems, once an alarm condition occurs, certain safety protocols are triggered to prevent accidental activation or malfunction of equipment like fans.

These fan systems need to be controlled carefully to prevent the spread of smoke or fire through the ventilation system once an alarm activates, necessitating a deliberate action to ensure safety and functionality. Restarting via a separate control element helps maintain this safety paradigm by allowing operators to assess the situation before re-engaging fans, thus ensuring that their operation does not inadvertently worsen the emergency conditions.

In contrast, some other options do not reflect the usual practices associated with fan operation in response to fire alarms. For instance, automatic resetting could lead to unintended consequences in a fire scenario, while relying solely on the alarm panel for activation may not provide the level of control needed during an emergency. Thus, the requirement for manual restarting emphasizes the importance of maintaining safety and control during an alarm condition.