Oklahoma Electrical Practice Exam

When mounting surface fixtures containing ballasts on a low-density cellulose fiber board ceiling, what is the minimum required distance from the surface?

1. 1 inch

2. 1.5 inches

3. 2 inches

4. 2.5 inches

The correct answer is: 1.5 inches

The minimum required distance of 1.5 inches from the surface when mounting surface fixtures containing ballasts on a low-density cellulose fiber board ceiling is established to ensure safety and prevent potential fire hazards. This distance allows for adequate ventilation around the fixtures, which is crucial because ballasts can generate heat during operation. Insufficient clearance could lead to overheating, which may compromise the integrity of the cellulose fiber material, increasing the risk of ignition. Furthermore, adhering to this distance requirement aligns with the National Electrical Code (NEC) and requires consideration of material properties and fixture design. The specification helps in maintaining safe operating conditions for both the fixtures and the surrounding materials, ensuring long-term reliability and safety in electrical installations.