Sources & Auxiliaries
Last Update: November 1, 2011
Adjust text size: Decrease text size.Restore text size.Increase text size.

HID Lamps

The proper application of HID lamps requires an understanding of the three major types - mercury, metal halide and high-pressure sodium - because the performance characteristics among types and even among lamps within those major types can vary widely, even uniquely.  All HID lamps require ballasts, which have a variety of characteristics as well.  The following discussion focuses on the metal halide and high pressure sodium lamps and systems since these types are the most efficient.  Among the metal halide designs, the “pulse start” systems are now the most efficient, but information about the older “probe start” design is also included because it is still widely used. Finally, this section describes the characteristics of low pressure sodium (LPS) lamps.  Technically, LPS lamps are not “HID” lamps since the arc inside the lamp does not operate at relatively high temperatures or pressures. However, LPS lamps are typically used for many high-efficacy lighting applications where HID lamps may alternatively be used.

HID Lamps and Systems
High intensity discharge (HID) lamps are characterized by small, bright arc tubes made from quartz or translucent/transparent ceramic materials. These arc tubes contain electric discharges of vaporized metals operating at relatively high temperatures and pressures. There are three main types of HID lamps: mercury vapor, metal halide and high pressure sodium.
More »

Science of HID Lamps
All HID lamps utilize a mixture of gases and metal vapors as the discharge elements in the arc tube. Arc tubes may be made out of quartz, which is strong, heat resistant and resists the chemical activity of mercury and the metal salts used in metal halide lamps.
More »

Metal Halide Lamps: Probe Start, Pulse Start and CMH 
Wattages of metal halide lamps range now from 15 to 2000 watts. A large number of envelope and base configurations are available.
More »

High-Pressure Sodium Lamps and Systems 
Since the arc tubes in high-pressure sodium lamps are stronger and smaller than those in metal halide lamps, the chances of arc-tube rupture is small. As a result, high-pressure sodium lamps do not require enclosures, except to prevent moisture from accumulating on the lamp.
More »

HID Ballasts
Ballasts for HID lamps must perform the usual functions of starting the lamp and regulating the power flow during lamp warm-up and operation, but the growing sophistication of metal halide and high-pressure sodium lamps has complicated those original tasks to the point that the traditional electromagnetic core and coil designs are now giving way to electronic/electromagnetic hybrids and even to completely electronic ballast systems to achieve optimum lamp performance over life.
More »

HID Application Guidelines
HID lamps are compact sources that lend themselves to projection and floodlighting situations as well as to general illumination. They are best suited to interior applications where lamp burning hours are long. Examples include manufacturing, corridor and display lighting as well as commercial area lighting.
More »

Low-Pressure Sodium Lamps
An older variant of lamps using sodium as the primary light-emitting material is the low-pressure sodium (LPS) lamp. These are not HID lamps since they are constructed more like fluorescent lamps and operate with relatively low internal pressures and temperatures.
More »

Sources & Auxiliaries

  =  Subscriber Content