Since their introduction as a commercial product in 1939, many different types of fluorescent lamp have been introduced. Systematic nomenclature identifies mass-market lamps as to overall shape, power rating, length, color, and other electrical and illuminating characteristics.
Tube designations In the United States and Canada, lamps are typically identified by a code such as FxxTyy, where F is for fluorescent, and the first number (xx) indicates either the power in watts for bi-pin lamps, length in inches for single-pin and high-output lamps, and for circular bulbs, the diameter of the circular bulb. The T indicates that the shape of the bulb is tubular, and the last number (yy) is the diameter in eighths of an inch (sometimes in millimeters, rounded up to the nearest millimeter). Typical diameters are T12 or T38 () for larger, often less efficient lamps, T8 or T26 () for smaller and often energy-saving lamps, and T5 or T16 () for very small lamps, which may even operate from a battery-powered device.
+ Fluorescent tube diameter designation comparison Designation Tube diameter Extra (in) (mm) Socket Notes T2 approx. 7 WP4.5×8.5d Osram's Fluorescent Miniature (FM) tubes Sylvania Luxline Slim T2 Linear T4 12.7 G5 bi-pin Slim lamps. Power ratings and lengths not standardized (and not the same) between different manufacturers T5 T16 15.9 G5 bi-pin 2GX13 quad-pin G10q quad-pin Original 4–13 W miniature fluorescent range from 1950s or earlier.Funke and Oranje, "Gas Discharge Lamps"; N.V Philips' Gloeilampenfabrieken (1951) Two newer ranges, high-efficiency (HE) 14–35 W, and high-output (HO) 24–80 W, introduced in the 1990s. Panasonic's range of FHL fluorescent tubes in 18W, 27W, and 36W varieties for the Japanese market. Circular fluorescent tubes. Thorn/General Electric 2D fluorescent lamps and other similar lamps from various manufacturers.T619.05 Fa8 single-pin
G10q quad-pin Single-pin fluorescent lamps.
Thorn/General Electric 2D fluorescent lamps and other similar lamps from various manufacturers. T8 T26 1 25.4 G13 bi-pin Fa8 single-pin R17d recessed double contact One of the first diameters of fluorescent lamps, with the 15W T8 and 30W T8 having been introduced in 1938. The European energy-saving krypton T8 lamps were introduced by Thorn EMI during the 1970s. The North American energy-saving argon T8 lamps weren't introduced until the 1980s. The newer European tubes from the 1970s are T12 retrofits if used with preheat/switchstart and electronic ballasts only, but the North American tubes from the 1980s have never been retrofits. T9 T29 28.6 G10q quad-pin G13 bi-pin Circular fluorescent tubes Some linear tubes T10 31.75 G13 bi-pin G10q quad-pin High-lumen retrofit lamps for 40W T12 lamps in North America. Popular tube diameter in Japan and Brazil. Circular 32W and 40W T10 lamps (Older versions of the 32W and 40W T9 lamps) T12 T38 38.1 G13 bi-pin Fa8 single-pin R17d recessed double contact One of the first diameters of fluorescent lamps, with the 15W T12 and 20W T12 having been introduced in 1938. These are less energy-efficient than thinner fluorescent tube formats and LEDs. T17 54 G20 Mogul bi-pin Large size for 90W T17 (preheat) and 40W T17 (instant start) PG17 54 R17d Recessed double contact General Electric's Power Groove tubes For T2–T12 and T17, the number indicates the tube diameter in inches, e.g. T2 → in and T17 → in. Whereas for T16 and T26–T38, the number indicates the approximate tube diameter in millimeters.
Reflectors
Some lamps have an internal opaque reflector. Coverage of the reflector ranges from 120° to 310° of the lamp's circumference.
Reflector lamps are used when light is only desired to be emitted in a single direction, or when an application requires the maximum amount of light. For example, these lamps can be used in tanning beds or in backlighting electronic displays. An internal reflector is more efficient than standard external reflectors. Another example is color matched aperture lights (with about 30° of opening) used in the food industry for robotic quality control inspection of cooked goods.
Aperture lamps have a clear break in the phosphor coating, typically of 30°, to concentrate light in one direction and provide higher brightness in the beam than can be achieved by uniform phosphor coatings. Aperture lamps include reflectors over the non-aperture area. Aperture lamps were commonly used in photocopiers in the 1960s and 1970s where a bank of fixed tubes was arranged to light up the image to be copied, but are rarely found nowadays. Aperture lamps can produce a concentrated beam of light suitable for edge-lit signs.
Single-pin lamps Single-pin lamps (Also generically called "Slimline" in the United States) operate on an instant start ballast in the United States and Canada or on a series choke without a starter in 220-240V countries.
High-output/very high output lamps High-output lamps are brighter and are driven at a higher electric current. They have a recessed double contact (R17d) base on each end, rather than a standard bi-pin base, which prevents them from being installed into the wrong fixture. Since about the early to mid-1950s to today, General Electric has developed and improved the Power Groove lamp. These lamps are recognizable by their large diameter () and grooved tube shape.
Colors Colors using a calcium halophosphate formulation are usually indicated by WW for warm white, W for (neutral) white, CW for cool white, and D for the bluish daylight white.
Philips and Osram use numeric color codes for tri-phosphor and multi-phosphor colors. The first digit indicates the color rendering index (CRI) of the lamp. If the first digit on a lamp says 8, then the CRI of that lamp will be approximately 85. The last two digits indicate the color temperature of the lamp in kelvins (K). For example, if the last two digits on a lamp say 41, that lamp's color temperature will be 4100 K, which is a common tri-phosphor cool white fluorescent lamp.
BL is used for ultraviolet lamps commonly used in bug zappers. BLB is used for blacklight-blue lamps employing a Wood's glass envelope to filter out most visible light, commonly used in nightclubs. Other non-standard designations apply for plant lights or grow lights.
Calcium halophosphate tubesJapanese color code Numeric color codeAlphabetic color code Color Approximate CRI Color temperature (K)N/A 29WW Warm white ≈52 3000WW 35W White ≈56 3500W 33CW Cool White ≈62 4000-4300N/A 25N/A Neutral/Universal White ≈75 4000NN/AN/A Natural Daylight ≈70 5000D 54D Daylight ≈75 6500 Deluxe halophosphate tubesJapanese color code Numeric color codeAlphabetic color code Color Approximate CRI Color temperature (K)L-EDL 27N/A Deluxe Extra Warm White ≈95 2700N/A 32WWX Deluxe Warm White ≈77 3000N/AN/AWXSylvania White Deluxe≈853500N/A 79N Natural ≈90 3600N/A 34N/A Deluxe White ≈85 3850W-SDL 38CWX Deluxe Cool White/ ≈90 4000N/AN/AC41GE Cool White Utility (Enhanced CWX)≈874100N-SDL, N-EDLN/AC50/DSGN50GE Chroma 50/Philips Colortone 50/Sylvania Design 50≈90-995000D-SDL, D-EDL 55DX Deluxe Daylight/Northlight/Colour Matching ≈88-98 6500N/AN/AC75GE Chroma 75/Philips Colortone 75≈927500700-series tubes (Calcium halophosphate and rare-earths tri-phosphor blend)Numeric color codeAlphanumeric color codeColorApproximate CRIColor temperature (K)730SP30/D30/TL730Warm White≈753000735SP35/D35/TL735Neutral White≈753500741SP41/D41/TL741Cool White≈754100750SP50/TL750Natural Daylight≈755000765SP65/TL765Cool Daylight≈756500 800-series rare-earth tri-phosphor tubesJapanese Color CodeNumeric color codeColorApproximate CRIColor temperature (K)ELX825Extra Warm White≈852500ELR, ELC827, 828Warm White≈852700, 2800EX-L, EL, ELK830Warm White≈853000ELW832Warm White≈853200EX-WW, EWW835Neutral White≈853500EW38838Neutral White≈853800EX-W, EW840, 841, 842Cool White≈854000, 4100, 4200EX-N, EN850Natural Daylight≈855000ENW, ENM, ENC852, 853Natural Daylight≈855200, 5300ENK855Natural Daylight≈855500ENX858Natural Daylight≈855800EDW862Cool Daylight≈856200EX-D, ED865, 867Cool Daylight≈856500, 6700ECW, EDK, EDC872, 874Cool Daylight≈857200, 7400EDF, EDX880Skywhite≈858000 900-series deluxe rare-earth phosphors tubes Numeric color code Color Approximate CRI Color temperature (K) 930 Warm white ≈95 3000 941 Cool white ≈95 4100 950 Natural Daylight ≈98 5000 965 Cool daylight ≈95 6500 Special purpose tubes Numeric codeAlphabetic Code Fluorescent lamp type Notes 05N/A Germicidal lamps No phosphors used in these lamps at all, and the enveplope is made of fused quartz instead of glass. In the American lamp code, the F as in FxxTyy is replaced by a G as in GxxTyy, indicating that it's a germicidal lamp. 08BLB Black-Light Blue lampsThese lamps are similar to the regular black light lamps, except they use wood's glass as a filter to reduce the amount of visible light emitted. These lamps are used for fluorescence effects where less visible light is ideal. 09N/A Sun-tanning lampsThese lamps produce wide or narrow band UV-B radiation10BLBlack-Light lampsBlack light lamps give off long-wave UV-A radiation of around 350-400 nm. They are often used to attract insects to traps. Unlike black light blue lamps, these lamps do not use wood's glass. They use regular soda-lime glass and emit more visible light than BLB lamps.
Common tube ratings
This section lists the more common tube ratings for general lighting. Many more tube ratings exist, often country-specific. The Nominal Length may not exactly match any measured dimension of the tube. For some tube sizes, the nominal length (in feet) is the required spacing between centers of the lighting fixtures to create a continuous run, so the tubes are a little shorter than the nominal length.
Tube diameter in Nominal length Nominal power (W)Lamp Code T5 Miniature 4F4T5 T5 Miniature 6F6T5 T5 Miniature 8F8T5 T5 Miniature 13F13T5T5/HE14F14T5T5/HE21F21T5T5/HE28F28T5T5/HE35F35T5T5/HO24F24T5/HOT5/HO39F39T5/HOT5/HO54F54T5/HOT5/HO80F80T5/HO T8 14F14T8T815F15T8 T8 17F17T8T82 ft (610 mm)18N/A T8 25F25T8T83 ft (914 mm)30F30T8 T8 32F32T8T84 ft (1,219 mm)36N/A T8 40F40T8T85 ft (1,524 mm)58N/A T8 70N/AT8 single-pin38F72T8T8 single-pin8 ft (2,438 mm)51F96T8T8 single-pin59F96T8T8/HO44F48T8/HOT8/HO55F60T8/HOT8/HO65F72T8/HOT8/HO86F96T8/HO T12 14F14T12 T12 15F15T12 T12 20F20T12T1230F30T12 T12 40F40T12 T12 65N/AT125 ft (1,524 mm)80N/A T12 75N/AT126 ft (1,829 mm)85N/A T12 125N/AT12 single-pin39F48T12T12 single-pin55F72T12T12 single-pin75F96T12T12/HO60F48T12/HOT12/HO75F60T12/HOT12/HO85F72T12/HOT12/HO110F96T12/HOT12/VHO115F48T12/VHOT12/VHO160F72T12/VHOT12/VHO215F96T12/VHO
European energy-saving tubes In the 1970s, Thorn Lighting introduced an energy-saving 8 ft retrofit tube in Europe. Designed to run on the existing 125 W (240 V) series ballast but with a different gas fill and operating voltage, the tube operated at only 100 W. Increased efficiency meant that the tube produced only 9% lumen reduction for a 20% power reduction.Thorn Lighting Technical Handbook This first energy-saving tube design remains a T12 tube even today. However, follow-on retrofit replacements for all the other original T12 tubes were T8, which helped with creating the required electrical characteristics and saving on the then new (and more expensive) polyphosphor/triphosphor coatings, and these were even more efficient. Note that because these tubes were all designed as retrofit tubes to be fitted in T12 fittings running on series ballasts on 220–240 V supplies, they could not be used in 120 V mains countries with inherently different control gear designs.
Type Diameter (in, mm) Nominal length (ft, m) Nominal power (W) Notes T8 1.0, 25 2, 0.6 18 Retrofit replacement for 2 ft T12 20 W T8 1.0, 25 4, 1.2 36 Retrofit replacement for 4 ft T12 40 W T8 1.0, 25 5, 1.5 58 Retrofit replacement for 5 ft T12 65 W T8 1.0, 25 6, 1.8 70 Retrofit replacement for 6 ft T12 75 W T12 1.5, 38 8, 2.4 100 Retrofit replacement for 8 ft T12 125 W