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PFC - Power Factor Correction - A capacitor usually included in the ballast.
Note: Newer systems may have 1 ballast including starters for all 3 tubes.

The system has 3 major components:

Tube - a mixture of gases, but the active ingredient is mercury. When operated as an arc, mercury vapour emits a vast amount of short-wave ultraviolet light. This is invisible, but phosphors on the inside of the tube itself fluoresce when struck by UV, and are designed to emit visible light.
See more on types of tubes.

ballast - The ballast limits the current to a safe value.

Old fluorescent tubes gave off an unnatural and unpleasant bluish-green color and the ballasts were magnetic which caused the lights to flicker at 60 Hz (cycles per second) (120 Hz if you count both off and on), the power line frequency.
Although humans cannot see fluorescent lights flicker, the sensory system in some individuals can somehow detect the flicker. Ever since fluorescent lighting was introduced in workplaces, there have been complaints about headaches, eye strain and general eye discomfort.
Today's fluorescent tubes and bulbs are vastly improved. State-of-the-art rare earth phosphors show true colors and natural skin tones. And flicker is totally eliminated with new electronic ballasts that operate as high as 20,000 Hz.

ballasts cost from $20-$30. See Replacement Ballasts - The Home Depot
Get one that matches your bulb type (T12, T8, T5).
  Some ballasts support both T12 and T8 bulbs which both use the G13 base
  Most ballasts are designed for one or the other.
  A T12 balast will shorten the life of a T8 lamp.

There are other things to consider.
Size and shape.
Number of bulbs 1-2-4
Instant start, programmed start, rapid start, pre-heat start and trigger start.
Dimmable - You may need a special dimming switch
  See Ballasts and Dimmers - What do I need to know? |
See How to Choose the Right F17T8 to F32T8 Ballast |
How to Replace the Ballast in a Fluorescent Lighting Fixture -
Google it

Starter - Starts the arc within the tube.
This is a small neon lamp, with a bimetallic strip contact mechanism built in. When power is first applied, the neon conducts a small current - enough to heat the bimetallic strip, and this causes the switch to close. Once closed, current flows through the filaments at each end of the tube via the ballast, bringing them to working temperature.

The standard 18 and 36W tubes (2' and 4') are now under serious threat. The new T5 tube is designed to use an electronic ballast, but unlike CFLs, the ballast is not thrown away with the tube - it's reused until it fails.The neon starter that's needed for iron-core ballasted tubes is no longer needed, and because the power requirement is reduced compared to a T8 tube, we can get the same (or more) light with less power.

Starters are about $2 each.

Types of Tubes
Type  Diameter   Efficiency      Cost (4' lamp)  Lumens per watt (LPW)
T12    1 1/2"	old inefficient                   78  
T8     1"       more efficient     $3-5           90
T5      5/8"    highest efficiency $5.50-12       99
 T refers to diameter T12 = 12/8" = 1/12" T8 = 8/8" = 1 in
 All lamps have a general life expectancy of around 36,000 hrs. at 12 hrs. per day burn time.
CRI - Color Rendering Index is a measure of how well colors can be perceived using light from a source, relative to light from a reference source such as daylight. By definition, an incandescent lamp has a CRI of 100. Fluorescent lamps with low CRI have phosphors that emit too little red light. Skin appears less pink, and hence "unhealthy" compared with incandescent lighting.
CRI's typically range from 62-85.

See Color Rendering Index (CRI) | Topbulb and High CRI Bulbs | Topbulb
and Color Rendering Index (CRI) Explained

Color spectra refers to the color, warm white, cool white, daylight, ...
See Lighting for more.

Tube Codes:

Bulb Types:

G13 holder works with T8 and T12 bulbs.

Trouble shooting:
Fluorescent Lighting Troubleshooting
If the lamps have turned black at one or both ends, they are bad.
Note they usually appear gray at the ends where the electronics are. Fluorescent lamps generally burn out gradually over time, not suddenly. If all of the tubes in a fixture stop working abruptly at the same time, it's likely that the problem is not the tubes. If the light fixture has one or more "starters" (found only in older fixtures), replace the starters. They are cheap.
T12 vs T8 vs T5: "T-12".
Does a T5 lamp give as much light as a T8 lamp? | What are T5 Lamps? | NLPIP - (National Lighting Product Information Program,) Rensselaer Polytechnic
Changing Fluorescent Light Ballast
Tube Lamps
Fluorescent Lighting Troubleshooting
Fluorescent lamp - Wikipedia
Finding the right compact fluorescent light bulb color
Philips Fluorescent tubes

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last updated 25 Mar 2015