When spacing smoke detectors on peaked ceilings, the distance to the peak is measured along which axis?

When spacing smoke detectors on peaked ceilings, the distance to the peak is measured along which axis?

• A. Horizontal axis
• B. Vertical axis
• C. Diagonal axis
• D. Radial axis

Answer: (A)

On peaked ceilings, the distance to the peak is measured along the horizontal axis. This means using the plan view projection and measuring straight across in the horizontal plane toward the apex. Doing so keeps detector spacing consistent with how the ceiling is laid out, regardless of the slope. If you measured up the slope (diagonal), the distance would change with the ceiling angle and could create uneven coverage. Vertical measurements relate to height above the floor, not distance to the peak, and radial measurements aren’t used because spacing follows a plan-view layout toward the apex.

On peaked ceilings, the distance to the peak is measured along the horizontal axis. This means using the plan view projection and measuring straight across in the horizontal plane toward the apex. Doing so keeps detector spacing consistent with how the ceiling is laid out, regardless of the slope. If you measured up the slope (diagonal), the distance would change with the ceiling angle and could create uneven coverage. Vertical measurements relate to height above the floor, not distance to the peak, and radial measurements aren’t used because spacing follows a plan-view layout toward the apex.