How does a fluorescent tube work?
A fluorescent tube is a tube made out of glass (with a fluorescent layer on it) that is filled with gas. On both sides of the tube we find steel pins to connect the tube in the fixture.
If we put electricity on the tube, the electrons inside the tube will start moving. That will cause the tube to produce infrared light. As human beings we cannot see infrared light, but because the tube has a fluorescent layer on the glass, that layer will light up and we have light.
What kind of gas is inside a fluorescent tube?
TL Tubes and their ballasts and starters
Every tube needs a ballast to work. The ballast makes sure the voltage is regulated for the fluorescent tube. There are 2 main types of ballasts:
- Conventional ballast: Has to be used incombination with a starter, works analog. An alternative term for conventional ballast is electromagnetic ballast.
- Electronic ballast: Does not need a starter and works digital
A starter only needs to be used in combination with a conventional ballast:
A movie of Philips with ballasts explained
Which different fluorescent tubes do we have and with which starters do they work?
Basicly we can determine 3 different kinds of fluorescent tubes:
- T12 (diameter of the tube: 40mm): Only works with conventional ballasts
- T8/TL-D (diameter of the tube: 26mm): Works with a conventional OR an electronic ballast
- T5/TL5 (diameter of the tube: 16mm): Only works with electronic ballasts
As you can see above, thinner tubes have been introduced during the years. That's because the thinner tubes are more energy efficient than the thicker versions. So thinner tubes needs less energy to produce the same amount of light.
Wattages and lengths of fluorescent tubes
Depending on the type of tube (T12, T8 and T5) the length of the tube is connected with the wattage of the tube.
The most common tubes are the T8/TL-D tubes in the following wattage/length:
- 60cm: 18W
- 120cm: 36W
- 150cm: 58W
Colour codes on fluorescent tubes
Most tubes are available in different colour temperatures. A colour temperature is the type of white light the tube has. Here you'll find an overview of the most common colour codes that are printed on the tube:
- 827: Very warm white, home use
- 830: Warm white, office use
- 835: White, office use, mainly used in The UK
- 840: Cool white, office, warehouse and factory use
- 865: Daylight, warehouse and factory use
The colour used by customers depends on the climate too. The warmer the climate, the cooler the light colour. So: In Spain 865 in common. In Finland 830 is common. The reason is: People feel cooler when the light colour is very bright white. So remember: Outside warm climate=Cool colour, Outside cold climate=Warm colour.
Explanation of the colour code:
|Colour code||Colour Rendering Index (CRI)||Colour temperature (Kelvin)|
On the left: 827, in the middle: 840 and on the right: 865
As you can see above, the colour code is splitted into 2 parts, the colour temperature (colour of the light) and the CRI. The CRI is the quality of the light. It's measured on a scale of 0 to 100. 100 is perfect quality of the light, all objects lighted up will look perfectly natural, just like sunlight. A low colour rendering means that the light quality is very bad and it's hard te determine one object colour from another.
Examples of a low CRI: The orange lights that light up the highway, you can't see the difference between one and another colour, look at the grass on the left with low CRI, on the right you'll see the high CRI lighting:
Different types of fluorescent tubes
Many different kind of fluorescent tubes, check the file for a complete overview.