NALMCO Certified Apprentice Lighting Technician (CALT) Practice Exam

What do HPS, all pulse-start MH lamps, and low-wattage MH lamps need to start?

1. A key

2. Parallel circuit

3. Starter or ignitor

4. Two ballasts

The correct answer is: Starter or ignitor

HPS (High-Pressure Sodium), pulse-start metal halide (MH) lamps, and low-wattage metal halide lamps require a starter or ignitor to initiate the lighting process. These types of lamps typically operate on a principle that necessitates a high voltage pulse to ignite the gas within the lamp. The role of the starter or ignitor is critical; it generates the necessary high voltage that momentarily increases the voltage across the lamp to overcome the initial resistance of the gas. Once the gas ionizes, it allows current to flow, and the lamp can operate normally. This starting mechanism is essential for the operation of these lamp types, which is why having a starter or ignitor is integral to their design. The other options mentioned do not adequately address the specific requirements for starting these lamps. For example, while a parallel circuit could be used in some lighting systems, it is not a requirement for starting these particular lamps. Ballasts are also crucial for maintaining the lamp's operation but do not function as the starting mechanism alone. Therefore, the need for a starter or ignitor is the defining characteristic of HPS and metal halide lamps when it comes to their starting requirements.