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Compact Fluorescent

Compact fluorescent light bulbs (CFLs) take advantage of rare earth phosphors to make possible small tube diameter (T4 = 1/2", T5 = 5/8") fluorescent bulbs. CFLs use single or multiple tubes bent in various ways to optimize performance in a small form factor. Always single-ended, the bases can be two or four pin, Edison screw base and twist-lock GU24 base. All CFLs require a ballast. In pin-based CFLs, the ballast is located in the fixture. In screw base CFLs, the ballast is integrated into the bulb. Some CFLs such as reflector and globe bulbs use a plastic envelope shaped like familiar incandescent bulbs to contain the CFL tubes. Compared to incandescent light bulbs, equivalent light output CFLs improve efficiency (lumens/watt) by a factor of about 4 to 1. For example, a 13 watt CFL replaces a 60 watt incandescent.

Compact Fluorescent Frequently Asked Questions:

What are the Option for High Wattage CFLs?

High wattage compact fluorescent (HW-CFLs) are bulbs in the 55W - 200W range. They are intended primarily for retrofit in HID fixtures (after the HID ballast is disconnected) or for retrofit in high-wattage incandescent fixtures.

HW-CFLs provide light output equivalent to incandescent 200W-500W; metal halide 70W-175W and high pressure sodium 50W-150W.

Benefits of HW-CFLs

  1. High color rendering and more color temperature options than standard metal halide and HPS
  2. Instant restrike after a power outage
  3. Medium and mogul screw base
  4. Better energy efficiency and lamp life compared to incandescent and competitive with metal halide and HPS

Drawbacks of HW-CFLs

  1. More suitable for general illumination rather than for directional lighting
  2. Enclosed fixtures may overheat the ballast electronics of self-ballasted HW-CFLs
  3. Frequent switching may shorten lamp life (therefore not recommended for use with occupancy sensor controls).


How Does Heat Affect CFLs?

Screw base compact fluorescent bulbs (CFLs) are designed so they can easily replace incandescent or halogen bulbs while providing both energy savings and longer life. Quality CFLs on the market today can come very close to matching the quality of light, instant on and even dimming characteristics of incandescent and halogen.

One area of comparative weakness has been that CFLs often come with the warning not to use them in "enclosed fixtures." Flush mount ceiling and wall fixtures and recessed downlights present a problem because of potential heat build-up inside the fixture.

The concern is not about fire. It's about the fact that excess heat, particularly around the base of the CFL, can cause premature bulb failure. Screw based CFLs are built with integral voltage transformers so they can be screwed into a 120V socket. Heat causes the transformer to fail prematurely. Hence the warning about "enclosed fixtures."

The good news is that there are CFLs in the 5W to 15W range that have special transformers built for high heat conditions. If you have an application that may require this type of CFL, please give us a call at 800.867.2852.