Fluorescent lamps are a common sight in a wide range of commercial applications. Basically, it is a low pressure tube filled with an inert gas and mercury. When electricity is passed through the electrodes, electrons stimulate the mercury atom to release UV light. This UV light causes the phosphor coating to “fluoresce”, creating the white glow that we are familiar with.

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Fluorescent lighting quickly took over incandescent lighting as the dominant light source in the 1950s. Incandescent lights create illumination by “incandescence”; an electric current is run through a filament until it glows with heat. This is highly inefficient since most of the energy consumed is to create heat, not light. Furthermore, the high running temperatures drastically limit bulb life.

Since fluorescence does not rely on heat to create illumination, fluorescent lights can have up to 20 times the working life of incandescent light bulbs. However, they still rely on an electrode/filament system which is prone to mechanical failure throughout the lifetime of the lamp. Each time the lamp is lit, the electrode degrades slightly. Fluorescent lamps will dim gradually from the moment installed until it reaches the end of its lamp life, which is indicated by flickering and unacceptable light output. Since the degradation is gradual, it is often very difficult to compare brightness unless an old and new lamp is placed side by side.