How a fluorescent bulb works

A regular light bulb uses a glowing filiment to produce light while a fluorescent tube uses mercury vapor that when ionized produces ultraviolet light that causes the lining of a fluorescent tube to glow which produces light. A fluorescent starter is timed switch that allows this process to start.

A fluorescent bulb circuit with bulb, starter, and ballast

The most common fluorescent starter is called a "glow tube starter" (or just starter) and contains a small gas (neon, etc.) filled tube and an optional radio frequency interference (RFI) suppression capacitor in a cylindrical aluminum can with a 2 pin base. While all starters are physically interchangeable, the wattage rating of the starter should be matched to the wattage rating of the fluorescent tubes for reliable operation and long life.

The glow tube incorporates a switch which is normally open. When power is applied, a glow discharge takes place which heats a bimetal contact. A second or so later, the contacts close and provide current to the fluorescent filaments. Since the glow is extinguished, there is no longer any heating of the bimetal and the contacts open. The inductive kick generated at the instant of opening triggers the main discharge in the fluorescent tube. If the contacts open at a bad time, there isn't enough inductive kick and the process repeats.

The problem with incandescent light bulbs is that the heat wastes a lot of electricity. Heat is not light, and the purpose of the light bulb is light, so all of the energy spent creating heat is a waste. Incandescent bulbs are therefore very inefficient. They produce perhaps 15 lumens per watt of input power.

A fluorescent bulb produces less heat, so it is much more efficient. A fluorescent bulb can produce between 50 and 100 lumens per watt. This makes fluorescent bulbs four to six times more efficient than incandescent bulbs. That's why you can buy a 15-watt fluorescent bulb that produces the same amount of light as a 60-watt incandescent bulb.

When a fluorescent aquarium fixture goes out, there may be several possible causes. Here are some troubleshooting tips:

A bad bulb will often be blackened at the ends and will start, but slowly. If the fixture is an older model with no starter (the switch must be held in to start the bulb), the lamp often turns itself off after a few minutes or hours. If the fixture has a starter (little silver can, most common size if FS-2), the lamp will often turn off, restart, and turn off repeatedly.

A bad starter will likely result in one of two extremes: either the lamp will not start at all (although oftentimes the ends of the bulb will glow) or it will start promptly, but begin flashing as the starter continues to attempt to start the bulb, even though it's already on.

In older models with no starter, failure of the four-wire switch also results in starting failure. If the starting circuit (usually red or blue wires) fails, the bulb may show a faint glimmer throughout. If the main circuit (black wires) fails, the bulb ends will glow, but upon releasing the switch, the bulb goes dark.

A bad ballast (transformer-looking device sometimes found on the cord on older models, but found under the reflector in many newer fixtures) is probably the worst case scenario. Since the ballast's job is to reduce the amount of current that goes to the bulb, a damaged ballast often results in immediate damage to the bulb. There is usually a flash of light, and occassionally even an implosion of the bulb itself.

If the fixture simply does nothing, it may be any of the above, or a number of other things, including a disconnected or broken wire, bad plug, bad switch - and hey, don't forget to check if it's plugged in! Sometimes it's best to take the whole light fixture, bulb and all, into the shop and let the dealer swap a few parts until he finds the problem.

www.fluorescentstarters.com is wholly owned and operated by David Tyson Lighting, Inc. located in Jacksonville, Florida. They have been in business since 1992 supplying business around the United States and Globally with long lasting lighting products at the lowest possible prices.

5515 St. Augustine Road
Jacksonville, FL. 32207
PH: 800-413-9847
FAX: 800-385-3149

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