Fluorescent lamps are a type of gas discharge lamp which generate invisible ultra-violet radiation and then use a phosphor coating on the inside of the lamp glass to convert this into visible light using a process known as “fluorescence”. By using different coating materials, fluorescent lamps can be made to generate light in a range of different colour temperatures. Typically these include Warm White, White, Cool White and Daylight versions.
The tube diameter is often expressed in eighths of an inch (e.g. T5 = 5/8” = 16 mm).
Advantages of fluorescent tubes include:-
- High energy efficiency
- Long operating life (typically over 10,000 hrs)
- Even light distribution.
Some fluorescent lamps are manufactured without the fluorescent coating and use a bluish black glass in order to deliberately emit only light in the ultra-violet (UV) spectrum. These are used for specialist applications such as banknote forgery detectors and nightclub special effects lighting.
Fluorescent lamps are generally designed to work directly from the mains (110 or 240V AC power) but require a starter and ballast or electronic gear to operate. Electronic control gear (ECG) converts mains power to a very much higher frequency and gives several advantages over conventional ballasts and starters including:-
- Greater efficiency and hence lower power consumption.
- Reduced flickering
- Faster starting
Usually manufactured in a tube shape, fluorescent lamps can also be found in circular, “U”-shaped and a variety of other specialist shapes.