Updated 30-X-2011
Incandescent
Introduction
Lamp Nomenclature
Fluorescent Colours
Early History
Technology
Operating Principle
Phosphor Types
Gas Fillings
Lamp Lifetime
Switching Frequency
Ambient Temperature
Operating Frequency
Dimming Operation
Lamp Designs
T12 Argon
T8 Krypton
T5 Krypton
T5 Miniature
(Very) High Output
Rapid Start
Instant Start
Non-Linear Tubes
Compact Fluorescent
Lamp Designs
Switch Start
Tandem Switch-Start
Semi-Resonant Start
Rapid Start
Instant Start
Resistor Ballast
High Frequency
DC Operation

Fluorescent Lamp Colours

Choice of Light Colour
Two key factors must be considered when specifying the colour of a fluorescent tube – the correlated colour temperature (CCT) and the colour rendering index (CRI). The colour temperature is largely a matter of personal taste. The general preference is to use cool colours for a business-like atmosphere (e.g. in offices, factories, shops) and warm colours for a social atmosphere (e.g. in hotels and the home).

However there is considerable variation between different countries in terms of the most popular fluorescent light colour. The clear favourite in both continental Europe and North America is 4000K Neutral White. In the UK however the preference is for 3500K tubes, which strikes a balance between creating a professional atmosphere whilst providing a feeling of warmth for a friendly working environment. In the colder climes of the Nordic countries the 3000K lamps are preferred, to provide a feeling of warmth when coming indoors. Conversely the hot conditions in Southern Europe lead their populations to prefer a cold colour light, which provides the perception of escaping out of the heat into a cool and comfortable interior space. In all of these countries however, the warmest 2700K tubes hold court in domestic and residential lighting where they come close to the favoured appearance of the dominant incandescent and halogen lighting. These local preferences are contrasted strongly by practically the whole of Asia, where practically all sales are for the cool daylight lamps of 5000-6500K, even for residential lighting. Some more detailed applications for the different colour temperatures are detailed in Figure F2.

Figure F2 - Typical Applications for different Colour Temperatures

When choosing the desired light colour it is crucial to stay within the boundaries of the empirically determined Kruithof diagram (Figure F3), so as to achieve a natural colour appearance. The use of high colour temperatures at low illumination levels results in a depressing visual environment where colours appear flat and dull. Conversely the use of warm colour temperatures at high illumination levels yields an unpleasant insipid yellow hue to the surroundings which disturb the feeling of well-being. The matching of the illumination level to the desired colour temperature is a key point that is often overlooked in modern lighting design.
Figure F3 - The Kruithof Diagram

Colour Coding Nomenclature
With the launch of the first fluorescent tubes, the choice of colours was restricted to a single shade of 'White' plus seven vibrant colours. The white was a neutral colour having a CCT of around 4000K. Soon this was joined by a lower colour temperature known as 'Mellow' or 'Warm White'. This was rapidly followed by a high colour temperature light intended to better match the 5600K of natural daylight, and these lamps were simply called 'Daylight'. During the 1950s and in particular following the invention of the halophosphate materials, dozens of additional shades of white made their debut, and these were later augmented by the so called Deluxe colours - which offered the same colour temperature as earlier tubes but with superior colour rendering properties. Around this time most manufacturers adopted a coding system in which a completely arbitrary two-digit number was introduced to define each colour.

This situation propagated until the early 1990s, by which time there was quite some confusion in the market. This was not only because of the great number of different colours and codes, but also because each manufacturer and global region had its own nomenclature. The situation was rationalised following the introduction of a highly logical three-digit colour coding system by GE-Thorn in 1990. Such was the simplicity of this system that during the rest of that decade it was adopted by most other manufacturers, and also extended to other discharge lamps. The general structure is illustrated below in Table F2, where the first digit defines the colour rendering group while the second and third denote the correlated colour temperature.

Code 1st digit = Colour Rendering 2nd + 3rd = Colour Temperature
530       5 = Ra 50-59 (now 47-56)       30 = 3000 K
640       6 = Ra 60-69 (now 57-66)       40 = 4000 K
726       7 = Ra 70-69 (now 67-76)       26 = 2600 K
850       8 = Ra 80-89 (now 77-86)       50 = 5000 K
965       9 = Ra 90-99 (now 87-100)       65 = 6500 K
Table F2 - Examples of Three-Digit Colour Codes

Some manufacturers continue to dual-brand fluorescent tubes with their original two-digit serial codes in addition to the modern 3-digit system. There is no logic to these older codes and they cannot be deciphered to reveal the colour properties without reference to the manufacturer’s literature. A fairly comprehensive cross-reference table of both historic as well as modern fluorescent colour codes from the key manufacturers is provided below in Table F3.

Halophosphate Whites (Nominal data for F40T12 lamps)
Description Code Philips Osram Sylvania GE-Thorn American CCT CRI CCx CCy lm/W
Extra Warm White 726 - - - Home-lite - 2600 73 0.454 0.400 61
Warm White 530 Warm 29 HNI 30 WW 129 Warm 29 Warm White 3000 52 0.440 0.403 74
White 535 UK White 35 23 W 135 White 35 White 3500 55 0.409 0.394 76
Cool White 640 White 33 HNH 20 CW 133 Cool 33 Cool White 4200 65 0.370 0.380 75
Universal White 740 Natural 25 HNW 25 UW 125 Universal 25 - 4000 75 0.380 0.380 65
Daylight 765 Daylight 54 10 / HNT 15 D 154 Tropical Day. Daylight 6500 75 0.313 0.340 63

Deluxe Whites (Obsolete) (Nominal data for F40T12 lamps)
Description Code Philips Osram Sylvania GE-Thorn American CCT CRI CCx CCy lm/W
DX Extra Warm 927 WWDX 27 Interna 39 Incand. Fluo. - - 2650 94 0.461 0.418 44
DX Warm White 830 Softone 32 HNI-Z 32 WWX DX Warm 32 DX WW 3000 85 0.439 0.402 50
Plus White 736 - HNI-DX 31 - Plus White 36 - 3600 74 0.399 0.382 73
DX White 839 34 HNW-Z 22 CWX - DX White 3850 85 0.382 0.370 50
DX Cool White A 940 Trucolor 38 HNG 35 - °KolorRite 38 DX Cool 4000 92 0.381 0.377 40
DX Cool White B 941 Trucolor 37 HNW-DX 21 - - - 4100 97 0.374 0.370 45
DX Daylight 5000K 950 Graphica 47 19 - - Chroma 50 5000 98 - - 46
DX Daylight 6200K 962 Col. Match 55 - DDX 155 Northlight 55 D65 6200 94 0.313 0.323 48
DX Daylight +UV 965 - - - Artificial Day - 6500 95 0.313 0.329 37
DX Daylight 7500K 975 Daylight 57 - - Abbot-Gibson Chroma 75 7500 94 - - 47

Triphosphor Deluxe 80 Series (Nominal data for F36T8 lamps)
Description Code Philips Osram Sylvania GE-Thorn American CCT CRI CCx CCy lm/W
Tri DX Extra Warm 827 Incand DX 82 Lumilux 41 Home DX 182 Polylux 827 - 2700 85 0.463 0.417 95
Tri DX Warm 830 WarmDX 83 Lumilux 31 WarmDX 183 Polylux 830 - 3000 85 0.440 0.405 95
Tri DX White 835 UK White 835 Lumilux 26 White DX 835 Polylux 835 SPX35 3500 85 0.415 0.400 95
Tri DX Cool White 840 White DX 84 Lumilux 21 Buro 184 Polylux 840 SPX40 4000 85 0.380 0.380 95
Tri DX Daylight 5K 850 Day DX 85 - DDX 185 - - 5000 85 0.346 0.359 92
Tri DX Daylight 6K 860 - - DDX 186 Polylux 860 - 6000 85 0.346 0.359 90
Tri DX Daylight 6K 865 Cool Day 86 Lumilux 11 - - - 6500 85 - - 90

Triphosphor Super Deluxe 90 Series (Nominal data for F36T8 lamps)
Description Code Philips Osram Sylvania GE-Thorn American CCT CRI CCx CCy lm/W
Tri SDX Ex. Warm 927 Incand DX 92 - - - - 2700 95 - - 63
Tri SDX Warm 930 93 Lumilux 32 WarmDX 193 Polylux 930 - 3000 95 0.435 0.401 65
Tri SDX Cool 940 94 Lumilux 22 Buro 194 Polylux 940 - 4000 95 0.387 0.371 65
Tri SDX Day 5K 950 95 ColorProof 12 - Polylux 950 - 5000 98 0.344 0.354 65
Tri SDX Day 6K 960 96 - - Polylux 960 - 6000 98 0.309 0.324 65
Tri SDX Day +UV 965 BioLight 96 Biolux 72 Activa 172 - - 6500 98 0.313 0.335 65

Coloured Light
Description Philips Osram Sylvania GE-Thorn CCT CRI CCx CCy lm/W
Blue 18 67 / HNE64 Blue Blue - - 0.187 0.143 18
Green 17 66 / HNE63 Green Green 7000 22 0.239 0.622 70
Gold (Halophosphate +Cadmium Filter) - 62 / HNE62 Gold Gold 5000 98 0.508 0.488 36
Yellow (Modern Cadmium-free type) 16 - Yellow - 2200 34 0.534 0.464 -
Orange - - Orange - - - 0.632 0.361 -
Peach - - - Peach - - - - 44
Pink - 61 / HNE61 Pink Pink - - 0.548 0.310 19
Red (Halophosphate + Cadmium Filter) - - Red Red - - 0.700 0.299 4
Red (Modern Cadmium-free type) 15 60 New Red - - - 0.713 0.285 -

Special Applications
Description Philips Osram Sylvania GE-Thorn CCT CRI CCx CCy lm/W
Radar Blue - - - Radar Blue - - 0.255 0.317 -
Radar Red - - - Radar Red - - 0.565 0.277 -
Shop Lighting - Extra Warm 36 Natura 36 Natural 136 Natural 4000 90 0.378 0.365 50
Food Display (Bread, Patisserie etc.) Shoplight 76 Natura 76 FoodStar 176 DX Natural 3600 92 0.390 0.356 50
Meat Display (Basic CRI) 79 - - - 3800 74 0.369 0.317 45
Meat Display (High CRI) - - - Rosetta 3200 86 0.380 0.310 45
Meat Display with reduced myoglobin - - Gourmet 175 - 3800 85 0.380 0.340 -
Plant Growth Spectrum 89 Fluora 77 GroLux Super-Gro 6200 37 0.325 0.261 30
Plant Growth Wide Spectrum - - GroLux WS - - - - - 41
Aquarium Fresh Water Aquarelle - AquaStar 174 - 10000 71 0.304 0.239 68
Aquarium Daylight UV Stop coating - - DaylightStar - 5000 85 0.346 0.359 95
Aquarium Coral growth - - CoralStar - - - 0.176 0.045 -
Reptile UVB Vitamin D3 Synthesis - - ReptiStar - 6700 95 0.308 0.338 -
SAD Treatment - Sky White - - 8000 85 - - -

UV / Actinic Radiation
Description Philips Osram Sylvania GE-Thorn Peak l l10% l90%
Blacklight Blue (Fluorescence Effects) 08 73 BLB BLB 365 350 390
Blacklight 350nm (Photochemistry) Actinic 09 - BL 350 BL 350 320 395
Blacklight Pure UVA (Insect Traps) 10 - BL Quantum - 370 350 390
Actinic 365nm (Diazo Copying) Actinic 05 78 - - 365 320 420
Super Actinic 420nm (Diazo Copying) Actinic 03 HNPs 70 - - 420 400 440
Actinic Green (Photocopiers) Actinic 14 72 - - - - -
Reprography Blue 66 - - - - - -
Reprography Green 50 - - - 542 - -
Germicidal - Destruction of DNA TUV - Germicidal Germicidal 254 - -
Medical - Psoriasis Medical 01 - - - 312 - -
Medical - Hyperbilirubinaemia Medical 52 71 Blue Bilirubin Blue 450 - -
Tanning Basic - Closed Glass Cleo 09 - PBC - 352 320 390
Tanning Professional - Open Glass Cleo Prof 109 - PBO - 352 300 370
Tanning Pink Effect Cleo Pink 209 - - - 352 320 390
Tanning UVB / Psoriasis 12 - - - 307 280 315
Table F3 - Cross-Reference Table of Fluorescent Colour Codes