Car bulbs and the law

Car bulbs and the law

You’re probably familiar with a lot of the laws that govern how we can use our cars. But what you might not know is that there are also laws covering the components inside them – including our bulbs.

United Nations (UN) legislation details how each car bulb should perform. This includes:

  • how bright the bulb should be (in lumens)
  • how much power the bulb should use
  • the shape/design of the bulb, including specification information on the location of the filament to ensure light output is correct

So, what does that mean for drivers on a practical level? Let’s take a look at some of the common areas that people have questions about.

Brighter car bulbs

Brighter bulbs are developed to help keep drivers safe by enabling them to see further down dark roads. A brighter bulb alone shouldn’t lead to additional glare, as the light output is clearly defined, and glare is normally an indicator of a different problem.

Brighter bulbs are completely road legal as long as they meet the regulations outlined above. Clever design, different thickness of filament, a precise filament location and blue banding are all used as methods to direct light where it’s needed without going over the legal limits.

While another way of achieving a brighter bulb is simply to turn the power up, going over the allowed wattage means it’s not a road legal bulb.

Whiter car bulbs

Whiter bulbs are also completely road legal as long as they meet the regulations outlined above. A coating is usually used to generate a whiter light and this blocks some of the light out. This means that some bulbs drop below the legal minimum of lumens required. While others may then increase their wattage to meet this minimum, this can lead them to be too highly powered to be road legal.

Knowing car bulb legislation is

HID bulbs

High intensity discharge (HID) bulbs have their own UN legislation, although it’s largely similar to the overarching rules. As long as an HID bulb meets the specifications in this legislation then it’s road legal.

One important rule with HID bulbs is that they should only be fitted in a vehicle that originally had HID bulbs. If your car originally had halogen bulbs, then it’s not road legal to install HID bulbs.

LED bulbs

There are two types of LED bulbs: Original Equipment (OE) and retrofit.

OE LED bulbs are completely road legal and fitted as standard by car manufacturers. However, OE LED bulbs are a non-replaceable part and so if the bulb fails then the entire headlight needs to be replaced.

Retrofitting is when you replace a standard bulb with an LED version. At the moment, it’s completely road legal for you to replace an internal bulb with an LED bulb. However, there’s no legislation to cover retrofitting external facing light sources and therefore LED exterior bulbs in this instance are not road legal.

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Or choose our Premium membership for a small monthly fee (or a one-off payment) to unlock exclusive member pricing on all motoring products and services online and across our stores, garages and Halfords Mobile Experts, as well as a variety of other benefits that will help you to keep moving for less.

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