ILCOS is the "International Lamp Coding System" according to IEC 1231, which is described in the international specification IEC TS 61231 from 1999 and published e.g. in DIN 49805 as a German standard.
The structure of ILCOS designations applies to:
Halogen incandescent lamps
High-pressure sodium lamps
Low-pressure sodium vapor lamps
High-pressure mercury vapor lamps
Metal halide lamps
Lamps/starters for special applications
to improve communication across the different lamp types
help with interchangeability and compatibility
improve clarity between international standards and manufacturer documentation
to enable correct lamp replacement
to be used as an additional marking on the luminaire
replace national and regional marking systems
The structure of ILCOS
The first letter stands for the lamp category:
V = automotive lamps
F = fluorescent lamps
I = conventional incandescent lamps
The next letters stand for the details:
Lamp shape, light color, design features (with one slash if applicable, other features with two slashes).
Numbers for indication of wattage
Numbers to indicate voltage
Numbers to indicate lamp socket
Numbers indicating the dimensions of the lamp
The different ILCOS versions
The ILCOS marking system makes it possible to compare and thus exchange lamps from different manufacturers - company-specific lamp designations are compared in a translation list.
ILCOS covers almost all lamp characteristics. In practice, this leads to a length of designations that is difficult to handle. Therefore there are three versions for the detail of the designations:
ILCOS L consists only of the letter part. A medium version ILCOS D consisting of the letter and number part is so detailed that the user can also exchange lamps from different manufacturers. The complete specification as ILCOS T contains the complete designation part and a standardization part, thus all specifications required for the application.
A rod-shaped T8 fluorescent lamp 58 W of light color 840 is designated according to ILCOS D as follows.
"FD-58/40/1B-E-G13-26/1500" - the meaning in detail:
FD double-ended lamp
40 Light color
1B for Ra from 80 to 89
E starting behavior: external starter, with preheating