We explain what xenon headlights are and how they work to keep you safe at night

Xenon headlights, in a similar fashion to halogens, get their name from the gas used inside the bulb. The function of the gas however, is completely different – the gas is vital in the production of light, rather than just prolonging the lifespan of the filament as in a halogen bulb.

How do xenon lights work?

As mentioned above, xenon lights are a very different from halogens and can be recognised on the road thanks to the blue hue they give off. They use an electric arc between two electrodes rather than a filament to produce light, and are often referred to as high-intensity discharge (HID) lights. Xenon gas is used as it helps establish an arc between the electrodes (and hence create light) at lower temperatures, but becomes less important when the bulb is up to temperature.

UK laws surrounding HID xenon bulbs

According to the letter of UK law, HID xenon lights are not permitted. However, European type approval regulations do allow them, and therefore they must be allowed on EU cars registered in the UK.