Replace high-intensity discharge (HID) lights with the longer-lasting, energy-efficient LEDs. Brightness is measured in lumens; the higher the lumens, the brighter the bulb. LED lights are perceived as brighter at night than high-intensity discharge light technologies, so they require fewer lumens to provide the same brightness. Match your old light’s wattage to find the right LED bulb. A bulb’s estimated yearly cost is based on 3 hours of usage per day at $0.11 per kWh.

Plug socket-ready bulbs into an existing fixture with a compatible ballast.

Ballast bypass bulbs eliminate the need for a ballast, so the socket must be wired directly to the power source.

Switch from the yellow light of high-pressure sodium to the white light of metal halide without changing ballasts. Brightness is measured in lumens; the higher the lumens, the brighter the bulb. Color rendering index (CRI) is a measurement on a scale of 0-100 of how accurately the light from a bulb represents an object's true colors; the higher the number, the more natural the colors appear. Any CRI value over 80 will show colors true to life. A bulb’s estimated yearly cost is based on 3 hours of usage per day at $0.11 per kWh. Bulbs cannot be sold to Canada because they exceed local regulatory limits on mercury content.

Bulbs with an EX39 base number will not burst when they fail.

Probe-start ballasts are often found in older installations.

Pulse-start ballasts turn on faster than probe start. Some include a starter, which increases bulb life.

Pair these starters with pulse-start ballasts for metal halide bulbs.