HID Lamp technology articles for metal halide, mercury vapor and HPS lamps and bulbs
Can a lamp of the same wattage be used with any ballast rated for that wattage, such as, a 400 W Metal Halide lamp with a
400 W High Pressure Sodium ballast?
No. A lamp will only operate properly when used with the ballast designed for that particular lamp. The lamps to be used with a
particular ballast are listed on the ballast label and in the ballast literature. Lamp and ballast compatibility is assured by matching the
American National Standards Institute (ANSI) designations for both the lamp and the ballast. Using a lamp that is not specified will
affect ballast life, lamp life or both. HID lamps all have specified unique operating characteristics. The ballasts have been designed to
operate the lamps within those specified parameters.
How does Metal Halide technology operate?
Metal halide lamps have an efficacy of 60 to 110 lumens per watt and have a warm-up time of 2 to 5 minutes. They have a re-strike time
of 10 to 20 minutes. Lamp wattages range from 20 to 1000W with lamp life of 6,000 to 20,000 hours. Specialty lamps used for sports
lighting feature wattages from 1500 to 2000W and have lamp life ratings of only 3000 to 5000 hours.
The advantage of metal halide lighting is its bright, crisp, white light output suitable for commercial, retail, and industrial installations
where light quality is important. However, light maintenance over the life of the lamps is less than optimal relative to other HID sources.
The standard arc tube for metal halide lamps has been quartz until the last five to ten years when ceramic arc tube technology was
developed. Ceramic arc tubes are predominantly used in low wattage (20 to 150W) lamps, though new designs up to 400W have
emerged in recent years. Ceramic arc tubes provide improved constant color over lamp life. This technology is ideal for lamp
applications requiring truer color as in fruit, vegetables, clothing, and other accent lighting in retail displays.
How does High Pressure Sodium technology operate?
High pressure sodium (HPS) lamps have an efficacy of 80 to 140 lumens per watt, a long lamp life of 20,000 to 24,000 hours, and the
best lumen maintenance of all HID sources. Wattages range from 35 to 1000W and the warm-up time is from 2 to 4 minutes. Re-strike
time is approximately 1 minute.
The biggest drawback of high pressure sodium is the yellowish color light output, but it is acceptable for use in many industrial and
outdoor applications (e.g., roadway lighting). High pressure sodium and metal halide lamps comprise the majority of HID lighting
How does Pulse Start Metal Halide technology operate?
Lamp manufacturers sought to improve standard probe start metal halide lighting (175 to 1000W). They did so by changing the
chemistry and fill pressure in the lamp arc tube to increase lumen efficacy (lumens per watt). These lamp improvements required
introduction of an ignitor or starter to provide a high voltage starting pulse, eliminating the internal starting probe and its bi-metallic
switch. Removal of the starting probe and switch from the arc tube construction allowed an optimized arc tube design and
manufacturing process. This technology improved the overall performance of metal halide systems. Lumen output per watt consumed
can increase by 25%. Lumen maintenance is improved as much as 15%, lamp life is extended, warm-up time is reduced to two minutes,
and there is some improvement in color rendition.
Adding an ignitor reduced re-strike time to 4 to 5 minutes from the standard metal halide lamp time of 10 to 20 minutes.
How does Mercury Vapor technology operate?
Mercury vapor lamps are the least efficient HID source, with an efficacy of 25 to 55 lumens per watt. They were developed as a more
efficient alternative to incandescent light with lamp life 20 to 30 times longer. Mercury vapor light color is bluish and lumen
maintenance is only fair when compared to other HID sources.
Its benefits are low cost and long life (in the range of 16,000 to 24,000 hours or more) and a wide range of wattages from 50 to 1000W.
Mercury vapor lamps require 3-6 minutes to cool down before they can be restarted. This interval is known as the re-strike time.
Mercury vapor lamps are most commonly used for roadway lighting with a strong niche in landscape applications.