When should a technician install a detector in relation to a beam that is less than 12 inches deep and less than 8 feet on center?

Installing a detector on the bottom of the beam is the correct choice because it maximizes the effectiveness of the detector in identifying smoke or heat rising from below. In spaces with low ceilings or where beams create potential obstacles for smoke movement, placing the detector at the bottom ensures it can sense smoke accumulation more directly as it rises.

In building codes and standards, specifically for scenarios where beams are less than 12 inches deep and spaced less than 8 feet apart, the bottom location is optimal for smoke detection, allowing for quicker response times in case of a fire. This method helps ensure that the detector is not obstructed and can function properly in its primary role of detecting potential hazards.

The other options might not provide the same level of efficiency; for instance, placing the detector at the top of the beam could hinder its ability to detect smoke that is still low to the ground. Similarly, installing it next to the beam or above it may create similar issues with detecting lower smoke levels effectively. These placements can lead to delays in sensing smoke, which could prove dangerous in an emergency situation.