Although you wouldn’t think so at first glance, headlight bulbs are high-precision products. While a normal household bulb distributes its light over a radius of just a few metres, a headlight bulb combined with the reflector has to transfer the light accurately onto the road at a distance much greater than 50 metres.
You are about to find out why quality during production plays such an important role, and why poor-quality bulbs have a significant influence on traffic safety — even if they carry E-mark approval.
Requirements from ECE R37
Halogen headlight bulbs are manufactured and approved in accordance with the legal requirements (ECE R37). The specifications include the permitted luminous flux in lumen, the electrical power consumption and, of course, all the dimensions from the glass bulb itself to the base. This specification aims to ensure, for example, that every approved H7 bulb fits in every headlight intended to be used with a H7 bulb and that the combination provides the correct light beam.