HID Security Lighting
High Intensity Discharge (HID) bulbs produce more light with less power than a standard halogen bulb. This makes them a popular choice for the economical. An 18 watt HID light can produce about the same illumination as a 55 watt halogen bulb while consuming less than a third of the electricity.
HID lighting uses bulbs without filaments. Instead, the bulb is filled with a gas that reacts to current by lighting up. Ballasts supply the proper voltage and control the current to make this possible. These ballasts are specific to the lamp itself and are not interchangeable.
HID lights also produce a whiter light that looks more natural than the slightly yellowish light of a halogen system. This also means that an HID light producing the identical number of lumens to a halogen light will appear to be brighter. This results in additional savings of electricity.
An HID lamp will last 3 to 5 times as long as its halogen counterpart. In normal use, an HID bulb should be good for more than one thousand ignitions. You can tell the light is approaching the end of its useful life when it begins to grow dim or starts only intermittently.
HID lights also run much cooler than their halogen counterparts. This makes them less of a fire and safety hazard.
With all these advantages, HID lights do have some drawbacks, listed below:
Slow to come on - This is the most obvious drawback. HID lights can take between 5 and 30 seconds to reach their peak illumination. This isn't a problem for applications where the light is tied to a darkness sensor. But it does make HID lights not a good choice for wall switch or motion sensor applications.
Radiation - In addition to visible light, HID lamps can emit ultraviolet and infrared radiation. Skin and eye irritation can result from close exposure to these lamps for more than 15 minutes.
Cleaning - The quartz tube that houses the bulb must be kept clean. If it becomes contaminated, wipe it off (AFTER it's been turned off for a while) with a lint free towel or a denatured alcohol swab. The need for occasional cleaning may make an HID not the best bet for hard to reach locations.
Disposal - HID bulbs contain metals such as mercury that can be hazardous to the environment. You'll need to make sure that your spent bulbs are disposed of safely.