NALMCO Certified Apprentice Lighting Technician (CALT) Practice Exam

Which of the following HID lamps has the best color rendering ability?

1. Standard HPS

2. MV

3. LPS

4. MH

The correct answer is: MH

Metal Halide (MH) lamps are recognized for having superior color rendering properties compared to the other options listed. The color rendering index (CRI) is a measure of how accurately light sources reproduce colors in comparison to natural light. MH lamps typically have a CRI value that can range from 65 to 95, depending on the specific type and manufacturing quality, making them effective for applications where color accuracy is important, such as in retail settings, art galleries, and sport arenas. In contrast, High-Pressure Sodium (HPS) lamps and Low-Pressure Sodium (LPS) lamps have significantly lower CRI values, which limits their ability to accurately render colors. LPS, in particular, is known for having a very low CRI, which is why it is often used in street lighting where color rendering is not critical. Mercury Vapor (MV) lamps also have lower CRI values than MH, making them less desirable for applications requiring high color fidelity. Thus, the reason Metal Halide lamps stand out in this context is due to their ability to produce light that is closer to natural daylight, effectively rendering colors more vibrantly and accurately compared to the other types of HID lamps listed.