When must the warning system on mobile plant operate?

The correct answer emphasizes a critical safety measure in mining operations involving mobile plant equipment. The warning system must operate when the mobile plant is starting and presents a hazard because this is the moment when there is an increased risk of accidents or injuries. The operation of the warning system serves to alert personnel in the vicinity of the potential danger posed by the starting machinery, thus providing them the necessary time to move to a safer location.

When mobile plant equipment engages, particularly during start-up, it can lead to unexpected movements or actions, making it vital for safety notifications to be active. This precaution helps to minimize the risk of collisions, injuries, or fatalities, aligning with safety regulations and protocols designed to protect workers on-site.

The other options do not appropriately reflect the safety requirements in this context. For instance, having the warning system off when no one is near the plant overlooks the potential for unforeseen circumstances where someone may approach unexpectedly. Relying solely on direction from management may not ensure consistent safety practice, as immediate hazards can present themselves regardless of managerial instructions. Lastly, operating the warning system whenever the plant is in operation could lead to alarm fatigue, where workers might become desensitized to warnings if they are always active, thereby reducing their effectiveness in truly hazardous situations