There are two ways to create the light from the lamp. One is to use the heat discharge method, and the other is to use the gas discharge method. The incandescent lamp is using the heat discharge method which creates the light by heating up the tungsten filament, whereas, the fluorescent lamp is using the gas discharge method which creates the light by using ionized gas or metallic steam within the lamp.

Incandescent Lamp is made by placing the tungsten filament within the vacuumed or gas filled glass bulb. The light is created by heating up the tungsten filament. Generally, the incandescent lamp should be replaced when the performance of the lamp is reduced to 50% under the normal condition. The average life of the regular tungsten filament incandescent lamp is about 1,000hrs.

Tungsten halogen lamp is a more developed version of the incandescent lamp. The lamp is filled with halogen gas which prevents the evaporation of the tungsten filament, thus reducing the blackening of the lamp. The strength of this halogen lamp is highly efficient luminous flux of 25?/w. Furthermore, over 2,000hrs of life span, stable luminous flux, light source color of cool white, and minimized size are also the strength of the halogen lamp.

Depends on which kind of gas is injected in the lamp, we can either see the actual light emitted from the lamp or the light converted from ultraviolet light through the luminous paint spread inside the tube. The tungsten wire electrode in one side of the fluorescent lamp discharges electrons toward the other side, then ultraviolet light is created when these discharged electrons collide with mercury atoms in the tube. Ultraviolet light, then, collide with fluorescent powder painted inside the lamp tube to emit the fluorescent light.

The life span of fluorescent lamp represents the economic life span. In general, when the luminous flux of the lamp is reduced to 0.8 of initial luminous flux, the economic life span of the fluorescent lamp is regarded as zero. On average, economic life span of the regular fluorescent lamp is about 1,500hrs, and if used with the electronic ballast, the life span will be extended to about 50% or more.

The ballast plays two roles for the lamp. One is to stabilize the light discharge by controlling the electric currency within the lamp, and the other is to support the starting process of the lamp. The electric voltage for the fluorescent lamp has a tendency to decrease as the electric currency of the lamp increases.

If this load is connected directly to the power circuit, the electric currency within the lamp will increase unlimited, then ultimately the lamp will be destroyed. In other words, the ballast prevents the increase of electric currency, and, in the long run, helps to create the stable light discharge.

Most people think it is time to change fluorescent lamp when the lamp is no longer turned on. However, it is not the correct assumption. In general, it is best to change the lamp when the performance of the lamp is reduced to 70%. It is difficult to calculate the definite changing period for the lamps used in average home, but, on average, the fluorescent lamp lasts about 6,000hrs under the regular home usage.

Therefore, it is best to replace the lamp once in every 1~1.5 years. This period, however, can be reduced by the unstable voltage change or the frequent turn on & off.

When you turn on a new fluorescent lamp and you see the light is wiggling, then it is called the snake effect. The snake effect is not a defective problem. If you turn off the lamp and turn it on again later, most snake effect will disappear. If the effect won't disappear even after the restart, perhaps the voltage or the fixture is not suitable for the lamp. In either case, the snake effect will not destroy the lamp.

What is the Anode Spot?

It is an explicit blacking phenomenon occurred near the electrodes resulting from emitted electron emissive material depositing on the wall of the tube at the end. It is ordinarily a sign of age in service. The factors which cause the anode spot are

(1.) Frequent starting

(2.) Voltage is too low or high

(3.) The use of ballast which fail to provide adequate current

(4.) Poor contact between base pins and holders

What is the End band?

It is a banding shape blackening phenomenon which appears on both ends of the tube. it is caused by the small amount of impure gas generated during operation. But it does not effect the light output or life.

What is the Mercury depositing?

Small black spots appears on the wall of the glass tube when it lamp has not been used for a long time. These spots are mercury spots and it does not effect on lamp performance.

What causes the blackening of the lamp?

- The life of the lamp is over after the long period of usage.

- Frequent turn on & off- Bad connection between the ballast and the starter

- Breakage of the condenser

These marks represent the kind, the size, and the color of the lamp.