HID Lamps:
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High Pressure Sodium (HPS) lamps were invented by GE and are marketed under the brand name Lucalox ®.

They are available in size from 35 watts to 1000 watts. Most Lucalox ® lamps are rated at 24,000 hours plus making them a very reliable and long life light source.

At end of life the lamps begin to cycle, that is they will suddenly go out and then come back on, all by themselves (repeatedly). This is usually a sign that it is time to change the lamps.

All HPS ballasts include a high voltage ignitor to start the lamps. This is sometimes a part of the ballast, in which case it cannot be replaced independently, but often it is separate. If a lamp is out the ignitor may be firing continuously trying to start the lamp. In the past this might have caused the ignitor to fail rapidly; today's ignitors are sturdier and can last as long as six months with the ignitor firing continuously. Yet it is important to replace dead lamps as soon as possible.