Automotive Bulb Regulations

The World Forum for Harmonization of Vehicle Regulations operates as a working party within the Sustainable Transport Division of the United Nations Economic Commission for Europe (UNECE). In this capacity, the forum plays a central role in developing, coordinating, and maintaining a uniform system of vehicle regulations — collectively known as UN Regulations. Through this ongoing collaboration, it brings together governments, manufacturers, and industry experts to establish common standards for vehicle design and performance. As a result, these regulations help simplify international trade, reduce technical barriers, and ensure greater consistency in safety, environmental protection, and product quality across global markets.

What is “E” Marking?

The “E” mark certifies that a bulb meets ECE Regulation Standards.

The mark, shown opposite, confirms that the bulb fully complies with all safety and performance requirements.

Notably, the number following the “E” identifies the country that granted approval — such as E11 for the UK, E4 for the Netherlands, or E1 for Germany. Importantly, this number indicates the testing authority rather than the bulb’s design origin, manufacturing location, or performance level.

At ELTA, we proudly source and supply bulbs that carry E-marks from respected authorities in the UK, Netherlands, and Germany. By working with these trusted certification bodies, we ensure every bulb meets the industry’s highest standards for quality and safety. Together, these approvals reflect our ongoing commitment to reliability, compliance, and customer confidence.

Meeting Regulation 37

Regulation 37 defines the standards for filament bulbs used in approved vehicle lamps, ensuring safety and performance on the road. However, it excludes interior applications such as dashboard, courtesy, and instrument lights, which fall under separate specifications.

The regulation focuses on two critical areas that determine both performance and safety:

Photometry – which ensures correct light output and an accurate beam pattern.
Geometry – which defines precise bulb dimensions and fit within the lamp assembly.

Geometry: Dimensional Tolerances

Bulb sizes and dimensions must remain within strict tolerances to ensure proper operation and produce an accurate, effective beam pattern. Even the smallest deviation in filament position, lens curvature, or base alignment can distort the beam, reduce visibility, and create glare for oncoming drivers.

To prevent this, engineers design and measure every bulb type to meet precise ECE specifications. These standards guarantee consistent optical performance across all approved manufacturers. With this dimensional accuracy, each ELTA bulb fits securely, focuses precisely, and delivers safe, reliable performance in its intended headlamp assembly.

Maximum Wattage & Luminous Flux

Bulbs must operate within a specified maximum wattage to protect vehicle wiring and electrical systems.

For example, a 12-volt H1 bulb cannot draw more than 68 watts, and its luminous flux must reach 1,550 lm ± 15% to meet regulatory requirements.

At ELTA’s in-house test facility, our team verifies luminous flux using precision light spheres. With both small and large integrating spheres available, we accurately analyse each bulb’s luminous flux and colour temperature, ensuring consistent performance and compliance across the entire range.

Understanding Kelvin Temperature and Light Colour

The colour temperature of bulbs must fall within specified tolerances.

For example H1 finished filament lamp emitting white light must be as follows:

limit towards blue: x ≥ 0.310
limit towards yellow: x ≤ 0.500
limit towards green: y ≤ 0.150 + 0.640 x
limit towards green: y ≤ 0.440
limit towards purple: y ≥ 0.050 + 0.750 x
limit towards red: y ≥ 0.382;

Amber and red bulbs must also fall within set boundaries as shown here:

Ensuring Accurate Beam Pattern and Light Distribution

Manufacturers must precisely produce halogen headlight bulbs to consistently deliver the correct beam pattern from vehicle headlamps. By maintaining this accuracy, the bulbs direct light exactly where it’s needed for maximum visibility and safety.

A compliant beam pattern, in turn, prevents glare for oncoming drivers while clearly illuminating pedestrians and the roadside. As a result, every journey feels safer and more comfortable for all road users.

To verify compliance, ECE regulations define exact light output levels and measure performance at specific points when the beam projects onto a wall 25 metres away.

Beam Pattern projected in Light Test Facility

Life Cycle Testing

Although R37 doesn’t specify a minimum bulb life, it refers to IEC 60810, which defines how lifespan is measured. Ultimately, true quality shows in longevity — how long a bulb continues to perform. At ELTA, we conduct rigorous life testing to verify long service life and ensure consistent reliability.

Bulb life is typically measured using two key values that indicate reliability over time:

B3 – the point at which the third bulb out of 100 fails, representing the early failure rate.
Tc – the point at which the 63rd bulb fails, showing the typical service life of the product.

Together, these values provide a clear indication of a bulb’s expected lifespan and overall durability.

For example, a B3/Tc rating of 350/550 means that three bulbs have failed after 350 hours, while 63 bulbs have failed after 550 hours of operation. In practice, life-cycle test conditions vary depending on the bulb type, ensuring that each product is evaluated under conditions that reflect its intended use.

IEC 60061: Dimensional requirements of base and caps

ELTA bulbs not only meet ECE requirements — they also comply with IEC 60061, the international standard governing lamp caps, holders, and gauges.

This standard defines precise dimensions and control gauges for every cap and holder type, ensuring complete interchangeability and safety worldwide.

By going beyond ECE regulations with IEC 60061 compliance, ELTA ensures every bulb fits securely, operates safely, and can be replaced with confidence anywhere in the world.