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Understanding the Compact Fluorescent (CFL) Lamp - Bulb, Light & Heat


Different types of CFL Lamps

CFL's comes with different shapes and sizes

CFL's comes with different shapes and sizes

What are the basic principles for making lamps?

Lamps (Light Source) are produced by using two principles, one by converting heat into light and second by discharging the mixture of material and gases. It could be described as under:

(1) Incandescent Lamp: Is the first produced light source invented by the great scientist, Mr. Thomas Alva Edison in the year 1879. These lamps work on the principle of heat. When the electricity is passed through inside the glass hallow, the tungsten filament gets heated and starts emitting light. But 80% of the energy is wasted in generating heat and only 20% is used for giving light. In the era of highly priced Electricity Power, these are now known as power hungry lamps. Due to their lower price, they are frequently used all over. These include GLS lamps (bulbs), halogen lamps etc.

(2) Discharge Lamp: The discharge lamp operates on discharge technology to give high luminous efficacy and long life. Here electrical discharges between the electrodes cause the filler materials and gases in the pre-coated tube to emit light. A suitable control gear is invariably used to limit the current and to ensure the light-up of the lamp. It comprises of low pressure and high-pressure type, based on various applications. These include Fluorescent Tube Lamps (Tube Light/FTL), Compact Fluorescent Lamp (CFL), Mercury Vapor Lamps, Sodium Vapor Lamp, Metal Halide Lamp etc.

(3) The light sources using the laser beam technology is said to be under development.



Why CFL is the best replacement for GLS lamp?

The construction of CFL being compact in size and comparable with GLS lamp hence is considered to be the best replacement for GLS lamp. Normal tube lights (FTLs) being longer (4 Ft.) in size and larger in dia (38 mm) are thus not worth comparing with CFL (12.3 mm dia).

It is therefore advised that CFL must be discussed at all times in reference to GLS lamp only. It will generate a good amount of confidence and interest with the prospects.

What is photometric?

Photometric is the testing measurement involving distance and direction of light by using sophisticated equipment by mounting lamp at an adjustable and measurable distance from the photometer head. It includes measurement of the intensity of light, luminance, color temperature, color rendering index etc. For measurement, accuracy a globe shape halo sphere is invariably used, which is pre-coated with barium sulfate suspension.

What is the thumb rule for replacing a GLS lamp?

The thumb rule is that a CFL replaces 5 times more wattage GLS lamp to the nearest of standard rating available in the market in terms of light output. It means that a similar amount of light output of 100W GLS lamp can be obtained by replacing it with a 20W EL lamp (20W i.e. 1/5th of 100W).

Important: The other thumb rule is neither try nor advise to replace FTL with CFL. CFL is the best replacement for GLS lamp as explained earlier.

Why there are the different base for different CFL lamps?

These are as per the international design primarily to ensure that lamp concerned is used with the matching fixture including ballast.

What is the CFL?

The CFL (Compact Fluorescent Lamp) is a vacuum discharge lamp and the latest in the line of revolution in the lighting arena. As the name suggests, the CFL is quite a bit like the normal fluorescent lamp, popularly known as tube lights; but necessarily compact in size. Apart from the size, the other major difference is the lesser amount of energy consumed by CFL. That’s why it’s truly called the Power Saver lamp, essential for all. In fact, the small size of CFLs makes it more versatile, usable and acceptable over the traditional lamps.

CFLs are the state-of-the-art energy saver lamps available in two versions: Core and Electronics. They save 80% energy, have a long life and come in a wide choice of colors and have high esthetics.

What is the construction of CFL?

The CFL consists of two parts, (1) a gas-filled coated tube(s) and (2) a magnetic or electronic ballast. The gas in the tube glows with ultraviolet light when electricity flows therein through the ballast. This in turns excites the triband phosphor coating walls inside of the tube, which emits visible light throughout the surface of the tube. CFLs are state-of-the-art energy saver lamps who come in two versions (1) Core/ PL/ Non-Retrofit / Non-Integrated Lamps, and (2) Self-Ballasted/ Electronic / Retrofit/ Integrated Lamps.

What is triband phosphor?

Triband phosphor is the mixture of various fluorescent elements called activators, essential for the development of luminescence. It helps convert short-wave length ultra-violet radiation into light.

Triband phosphor is the most superior quality phosphor, capable of emitting red, green and blue wavelengths as against the ‘halophosphor’ with red and blue properties, which is used for ordinary fluorescent lamps (FTLs). Given the small dia tubes of CFL (12.28 mm) in comparison to FTL (38 mm), the use of triband phosphor ensures better and uniform light output throughout the life of the CFL. Triband phosphor is 10 times costlier than the halophosphor. The sub-standard spurious CFLs available in the market are largely made of using halophosphor and thus are cheaper in price.

What are the characteristics of 4 Pin CFL?

4 Pin CFL is specially designed for electronic operation to offer the possibility of controllable light output (dimming ), HF (High Frequency) and DC (Direct Current) supply; and a wide range of supply voltages when operated in conjunction with electronic gear. Electronic gear enables better control of lamp starting characteristics, allowing for an instant start which results in longer lamp life. In view of its favorable color rendering properties, the 4 Pin lamp is very suitable for use wherever light contributes to the creation of a flicker-free and pleasant atmosphere such as in hotels, restaurants, at homes, offices and so on.

What precautions are suggested for the best results from CFL?

Do not use in enclosed fittings.
Do not use in dimming circuits electronic switches.
Run on stable voltage.
Fragile-Handle with care.
Do not expose to water.
Do not hold from the glass.


Low electricity bills: CFL produces 90% less heat and hence gives more light per watt. It cuts electricity bills by almost 80% in comparison to the traditional incandescent lamp ( Popularly known as bulb or GLS lamp), which is considered to be power hungry light source. Whereas CFL is the most energy efficient light source.

Higher luminous efficacy: Gives more light output per watt of electricity consumed in comparison to the GLS lamp. An 11W CFL produces around 540-580 lumens compared to 710 lumens by a 60W GLS lamp. So it is 49 for CFL against 12 of GLS.

Long life: CFLs are available in a wide life range of 3000 hours to 12000 hours as compared to GLS lamp’s standard life range of 960 hours to 1200 hours only.

Available in different color temperatures: To suit various ambiance needs, these are ready, available in Warm White (2700°K) close to GLS lamp, Cool White (4300°K) and Cool Day White (6500°K) similar to tube light.

Enhances color rendering: The objects are seen in their true and natural colors under CFL lights. Color Rendering Index (CRI) is exceeding 80.

Lower installation cost: As most of the CFLs are worthy to fit or making it easily fit in the existing installation itself.

Lower replacement cost: Longer life reduces the frequency of replacement and thus keeps the replacement cost low especially, for installation put up at abnormal heights in the hotels, auditoriums and in developed countries where labor overhead expenses are innumerous.

Less heat dissipation: Unlike the GLS lamps, the CFLs by turning more energy into light than heat helps save on room cooling cost, such as air conditioner, refrigerators etc.

Universal burning position: More versatile lamp than many others having this constraint like metal halide lamp.

Enhances esthetics of the installation: Being trendy and compact.

Slim and compact design: makes it suitable for creative luminaires.

Wide range to suit all requirements: Available in 3, 5, 7, 9, 10, 11, 13, 15, 18, 20, 23, & 26W as compared to restricted usable range of 15, 25, 40, 60, 75, & 100W in GLS lamps.

Demand-side reduction for power: The use of CFLs reduces energy consumption by 80% and thus helps in better demand-side management for power. The calculation shows that the mere replacement of 100W GLS lamp by 20W CFL generates saving of approximate 800 KW Hrs over CFL lamp’s average life.

Most advantageous for DG set operations: As CFL consumes the lowest wattage per lamp.

Economical storage and distribution cost: Due to their compact size.

Environment-friendly: Power saved is power generated and helps in preventing a great deal of carbon dioxide and sulfur dioxide coming from the power generating thermal plants otherwise. Ultimately, enhances the quality of human life and nature around us.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2010 Binoy


Ray from USA on August 05, 2012:

Fantastic explanation. Voted Up and Shared! Thanks for Sharing!