NALMCO Certified Apprentice Lighting Technician (CALT) Practice Exam

Branch circuit conductors within how many inches of a ballast shall have an insulation temperature rating not lower than 90 degrees Celsius?

1. 3 inches

2. 6 inches

3. 2 inches

4. 1 inch

The correct answer is: 3 inches

The requirement that branch circuit conductors within a specific proximity to a ballast must have an insulation temperature rating of not lower than 90 degrees Celsius is based on the risk of heat buildup near the ballast. Ballasts, especially in fluorescent fixtures, can generate significant heat during operation. When conductors are located within 3 inches of the ballast, they are at a higher risk of being affected by this heat. Insulation rated for 90 degrees Celsius ensures that the conductors maintain their integrity and safety under higher temperature conditions. If a lower temperature rating was used, the insulation could degrade over time, potentially leading to short circuits, failed electrical connections, or even fire hazards. Choosing an insulation rating of at least 90 degrees Celsius for conductors in proximity to the heat source (the ballast) is crucial for ensuring the long-term reliability and safety of the electrical system.