T number
The tube diameter in eighths of an inch: T5 about 16 mm, T8 1 inch or about 25 mm, T12 about 38 mm.
Reference tool — not a selection
Lamp codes, before they go in an RFQ.
Lamp code
Diameter, base, colour.
Enter the code from the lamp or its box. Put an offered replacement’s code in the second field, and the reader checks the base, diameter, power, colour and length. The drawing and the RFQ line update with every change.
Examples:
Replacement check
On the codes alone: the lamp’s data sheet and the fitting decide.
All 130 engineering tools
A tube lamp or its box carries a code such as T8 36W/840 G13: diameter, watts, colour and base. LED replacement tubes carry the same marks. Enter the code, and the reader takes it apart, draws the tube in its colour and writes the RFQ line.
The code does not set the length, and the brand prefixes (TL-D, L, F and the rest) are each maker's own. Take the length from the data sheet or measure it.
How the code is built
T, G, watts and three digits.
G base
The number after G is the pin spacing in millimetres: G5 on T5 tubes, G13 on T8 and T12 tubes.
Colour code
Three digits: the first the colour rendering group, the last two the colour temperature in hundreds of kelvin. 840 is group 8, 4000 K; 865 group 8, 6500 K.
| T number | Inch | About, mm | Base |
|---|---|---|---|
| T5 | 5/8 | 16 | G5 |
| T8 | 8/8 | 25 | G13 |
| T12 | 12/8 | 38 | G13 |
The American code FxxTyy: xx is the watts of a bi-pin tube but the length in inches for slimline and some high-output tubes (F96T8 is 8 feet; on T5 HO it is the watts again, F54T5HO is 54 W); yy is the diameter.
Sources
T number, bases and colour code: Wikipedia ("Fluorescent-lamp formats"), lights.ie and paclights (T8 and G13), lamptech ("FL Colours"); the F code: Wikipedia, Philips F32T8 notes and a GE F96T8 listing. The colour rendering bands and the tube lengths differ between the sources and are left out.
Before you send the request
Questions about lamp codes in an RFQ
What does 840 mean on a tube?
The first digit is the colour rendering group, 8, and the last two the colour temperature in hundreds of kelvin, 4000 K. The exact Ra is on the lamp data sheet.
What do T8 and G13 mean?
T8 is the tube diameter in eighths of an inch, 1 inch or about 25 mm. G13 is the bi-pin base with the pins 13 mm apart, the usual base of T8 and T12 tubes; T5 tubes use G5.
Why does the reader not give the length?
Makers and markets state tube lengths differently, nominal or overall, so the code alone does not settle it. Take the length from the data sheet or measure the old tube with its caps.
What should the request include?
The diameter and base, the watts, the colour code, the length, whether a fluorescent tube or an LED replacement is wanted, and the quantity; for LED tubes, whether the fitting keeps its ballast.
Code clear?
Send the line with a photograph of the lamp.
Reading the code is a cross-check, not a selection. Attach photographs of the tube and the fitting, and Vessel Core checks them before an offer goes back.
Buyer tools
