Compact Fluorescent Lighting (CFL) has been so successful in replacing the traditional light bulbs (incandescent) and fit in existing light fixtures to produce more energy-efficient lighting. Edward Hammer developed the spiral shaped bulb to try to pack in enough tube yet allow enough space between the coils to decrease blockage of light. Today, Hammer’s spiral design endures, although rectangular tubular-type CFLs are a bit more efficient and are more popular in Europe.
There are two main components of a CFL:
- The ballast, which emits and moderates electric current (typically in the ‘bulb’ part of light)
- The gas-filled tube, also known as the bulb
The CFL tube is filled with an inert gas, typically argon but sometimes neon. This may also include a small amount of mercury vapor. As the larger fluorescent tubes, excited mercury atoms produce UV light. This strikes the phosphor coating on the inside of the glass tube or bulb to emit visible light.
In all fluorescent bulbs, the phosphor coating is a key part of the design and is constantly evolving. It is primarily the part of the bulb that produces light color, strength and quality. Today, most CFLs use a layering of two or three phosphors and in some occasions a five layer phosphor. Most CFLs have electronic ballasts, although some earlier models used a magnetic ballast that would cause a flicker in the light it produced and would sometimes hum.
Integrated vs Nonintegrated CFLs
CFLs can be manufactured as integrated or nonintegrated units. Integrated lamps combine the tube and ballast into a single product and have either an Edison screw-type or bayonet fitting. These are the CFLs that ar most familiar to consumers and they allow simple replacement of incadescent bulbs. This lowers the coast of use because people can actually reuse existing hardware.
Nonintegrated CLFs have a separate replaceable bulb and permanently installed ballast. Since the ballasts are placed in the light fixture, they are larger and last longer than the integrated ones. Nonintegrated housing tends to be more costly ranging anywhere from $85 to $180 for each recessed light fixture.
Direct Current (dc) CFLs
Most fluorescents will work on dc as long as there is enough voltage to sustain an arc. Unless the starting switch is arranged to reverse the polarity of the supply to the lamp each time it is used, the mercury in the tube will accumulate at one end of the tube. One alternate solution for this problem is to hook up an inverter before the fluorescent light, which will convert the power from dc to ac.
Advantages of CFL Lighting
Most residential CFLs opperate on 12 to 24 watts of energy which is far less than the typical 60 to 100 watts for incandescent bulbs. The great thing about this type of lighting is the CFL is still able to produce the same amount of light with a fraction of the energy. CFLs also have a longer life, sometimes 8 to 10 times that of an incandescent bulb. Even though the CFL bulbs cost more, with a longer life and a fraction of the energy use, you can expect to save anywhere from $25 to $35 over the life of the bulb according to the EPA.