IEC 61231 International Lamp Coding System (ILCOS)

💡 Core Insight: IEC 61231 establishes the International Lamp Coding System (ILCOS), providing a unified, structured identification scheme for all electric light source products. ILCOS covers incandescent, fluorescent, LED, high-intensity discharge (HID), and other lamp types, enabling the lighting industry to accurately identify electrical parameters, dimensions, and cap types through standardized codes.

1. ILCOS Code Structure and Formatting Rules

The ILCOS code uses an alphanumeric, structured format composed of multiple fields, each encoding a specific lamp parameter. The standard format is:

ILCOS Code = Lamp Type Identifier + Rated Power + Voltage/Current Parameter + Dimensional Code + Special Characteristics

The fields are defined as follows:

Lamp Type Identifier (2–4 letters): Encodes the basic light generation principle and construction. Examples: IN = Incandescent, FL = Fluorescent Linear, LED = Light Emitting Diode, HPS = High-Pressure Sodium, MH = Metal Halide.
Rated Power (numeric): Power in watts, e.g., 60 for 60 W.
Voltage Parameter (letter + numeric): Includes voltage type (A = AC, D = DC, U = universal) and rated voltage value.
Dimensional Code: Encodes physical dimensions (length, diameter, cap type) using standardized abbreviations.
Special Characteristics (optional): Indicates special features such as dimmability (DIM), high CRI, or specific color temperature (e.g., 830 for 3000 K, CRI 80).

⚠ Coding Note: Common misinterpretations to avoid: FL denotes linear fluorescent tubes only; compact fluorescent lamps use FS (Fluorescent Self-ballasted) or FQ (Fluorescent Quad-tube). For LED lamps, the ILCOS format is LED- followed by a specific construction identifier (e.g., LED-R for LED reflector lamps, LED-A for LED A-type lamps).

2. ILCOS Code Examples by Lamp Type

Lamp Type	ILCOS Code Example	Meaning
Incandescent (A-type)	IN-A60-230E27	Incandescent, A-shape, 60 W, 230 V, E27 cap
Linear Fluorescent	FL-T8-36W-830-G13	Linear fluorescent, T8 (26 mm dia.), 36 W, 3000 K CRI 80, G13 cap
Compact Fluorescent	FSQ-20-230E27	Self-ballasted CFL, 20 W, 230 V, E27 cap
LED Bulb	LED-A60-10-230E27	LED A-type, 60 W equivalent (10 W actual), 230 V, E27 cap
High-Pressure Sodium	HPS-T-70-E40	HPS, tubular, 70 W, E40 cap
Metal Halide	MH-T-150-E40	Metal halide, tubular, 150 W, E40 cap
Halogen Reflector	HSG-GU10-50-230	Halogen reflector (GU10 cap), 50 W, 230 V
LED Tube	LED-T8-18-230G13	LED tube, T8 replacement, 18 W, 230 V, G13 cap

✅ Best Practice: In lighting engineering design or product procurement, it is recommended to include both the ILCOS code and the traditional product model in technical specifications. ILCOS facilitates cross-brand comparison and alternative selection, avoiding mismatches due to different manufacturer naming conventions. This is especially valuable in LED retrofit projects where precise matching of light source dimensions and light center length (LCL) is critical.

3. Application Value of ILCOS in Lighting Engineering

The ILCOS design and application provide several important benefits to the lighting industry:

Standardized Procurement: Purchasers can precisely specify lamp requirements using ILCOS codes, avoiding errors caused by diverse manufacturer model numbers.
Inventory Management: Warehouse systems using ILCOS as the unified identifier enable standardized multi-supplier inventory control.
Retrofit and Compatibility: ILCOS provides a brand-independent product specification language, helping engineers quickly assess replacement suitability during lighting system upgrades.
International Trade: ILCOS transcends language and brand barriers, providing a common language for international lighting product trade and logistics.

IEC 61231 also specifies a code registration and management mechanism. New lamp product codes are assigned and managed by an IEC-designated registration authority to ensure global uniqueness and consistency. The rapid evolution of LED lighting technology drives continuous extension of the ILCOS system — coding definitions for novel LED constructions such as filament lamps, COB modules, and smart luminaires are under ongoing development.

🔴 Critical Warning: ILCOS provides standardized lamp identification but does not replace safety certifications (CE, UL, CCC) or performance standards (luminous flux, CRI, lifetime). ILCOS conveys basic specifications only — complete certification and performance data must still be referenced when selecting products. Additionally, products from different manufacturers sharing the same ILCOS code may differ in light quality and longevity.

4. Frequently Asked Questions

Q1: What is the difference between ILCOS and the American National Lamp (ANL) coding system?

A: ILCOS is an international standard (IEC) for global use, while ANL is the US national standard (ANSI) lamp coding system. ILCOS covers a wider range of lamp types with a more flexible structured format. In practice there is some overlap, and many international lighting products carry both ILCOS and ANL codes.

Q2: Does the power field in an LED lamp ILCOS code represent equivalent or actual power?

A: The standard requires actual input power in watts, not incandescent equivalent power. For example, a 10 W actual power LED bulb with 60 W equivalent brightness should show “10” in the power field, not “60.” Equivalent information can be supplemented in the model designation.

Q3: Does the ILCOS code include color temperature and CRI information?

A: Yes, through the special characteristics field. For example, 830 in FL-T8-36W-830-G13 indicates 3000 K color temperature and CRI 80. However, not all lamp types include this information in the code — always consult the product datasheet alongside the code.

Q4: Will ILCOS be updated as LED technology evolves?

A: Yes, IEC 61231 is periodically revised to incorporate new light source technologies. Recent editions have added coding rules for LED modules, OLED luminaires, and smart tunable-white lamps. It is advisable to follow the latest IEC standard revisions for current coding support.