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Metal-Halide Lamp is an high-intensity discharge light source in which the light is produced by the radiation from mercury, together with the halides of metals such as sodium and candium.
Metal-halide lamps are a member of the high-intensity discharge (HID) family of lamps.
Since the lamp is small compared to a fluorescent or incandescent lamp of the same light level, relatively small reflective luminaires can be used to direct the light for different applications (flood lighting outdoors, or lighting for warehouses or industrial buildings).
Like most HID lamps, metal halide lamps operate under high pressure and temperature, and require special fixtures to operate safely.
Metal-halide lamps require a ballasts to regulate the arc current and deliver the proper voltage to the arc. Like high-pressure mercury vapour lamps, some metal-halide bulbs contain a third electrode to initiate the arc when the lamp is first lit, which generates a slight flicker when the lamp is first turned on.
Pulse-start metal-halide lamps don’t contain a starting electrode, but they require an ignitor to generate a high-voltage (1–5 kV on cold strike, over 30 kV on hot restrike) pulse to start the arc.
