ECE R38

Everything you need to know about ECE R38: regulations for rear fog lights

Why is ECE R38 important?

A rear fog light warns drivers behind you when visibility is severely reduced. It is precisely at such times that the light must be noticeable without causing glare: if it is too dim, it will be spotted too late; if it is too bright, it will distract the driver behind you. ECE R38 therefore sets out requirements for, amongst other things, the colour, light output and light distribution of the light, as well as the durability of the light. A light approved in accordance with this regulation bears an ‘E’ mark bearing the regulation number.

Regulatory specifications

ECE R38 sets out the requirements for the light itself: the red light colour, the light output within specified limits, the light distribution across the prescribed angles, and resistance to moisture, dust and vibrations. A complete overview of the technical requirements can be found in the official UNECE text of Regulation 38. Where the light may be positioned on the vehicle and how many rear fog lamps are permitted is not specified in R38 but in ECE R48, the regulation governing the installation of vehicle lighting.

Compliance with the ECE R38 standard

Vehicle and lighting manufacturers must demonstrate that their rear fog lights comply with ECE R38. In the Netherlands, a rear fog light may only be switched on when visibility is less than 50 metres due to fog, snow or rain; the requirements for its use are set out in the RVV 1990. For those who build or convert vehicles, this means two things: choose a light with the correct approval, and connect it in accordance with the installation regulations.

ECE R38 and ECE R148

ECE R38 is one of the nine regulations brought together under ECE R148, the regulation governing light-signalling devices. New approvals for rear fog lights may therefore fall under R148. Existing approvals under R38 remain valid; specific provisions apply to the transition under each regulation. In practice, therefore, you will still see both designations used side by side on lights and in datasheets.

Innovations in vehicle lighting

Rear fog lights have also largely switched to LED. This results in a longer service life, lower power consumption and a light that is immediately at full brightness. On trailers and semi-trailers, the rear fog light is often combined with other functions in a single unit. You can read more about the technology behind this under ‘LED chip’.

ECE R38 remains the benchmark against which a rear fog light must comply. Anyone purchasing or fitting lighting should therefore check for the E-mark on the lens or housing and the manufacturer’s type-approval document. This ensures you can be certain that the light does what it is supposed to do when visibility is lost.

Looking for a rear fog light with the correct certification? Take a look at our ECE R38-certified lighting or the full range of LED rear lights. If you’re unsure about the right choice for your vehicle, our technical advisers will be happy to advise you.