How to use fog lights properly

Driving in fog can be scary and dangerous, but Motoring Research claims almost two thirds of drivers use their fog lights incorrectly. If you use your fog lights in the wrong way, you could land yourself a £50 fine.

Although there are no specific laws against not using fog lights, police can issue a fixed penalty notice for driving without due care and attention if visibility is significantly reduced. To keep both yourself and others safe, it’s important to know how and when you should use your vehicle’s lights.

What does The Highway Code say about fog?

Driving in foggy conditions is covered by The Highway Code’s Rules 234 to 236:

Rule 234

Before entering fog check your mirrors then slow down.

If ‘Fog’ is shown on a sign but the road is clear, be prepared for a bank of fog or drifting patchy fog ahead. Even if it seems to be clearing, you can suddenly find yourself in thick fog.

Rule 235

When driving in fog you should

• use your lights as required
• keep a safe distance behind the vehicle in front. Rear lights can give a false sense of security
• be able to pull up well within the distance you can see clearly. This is particularly important on motorways and dual carriageways, as vehicles are travelling faster
• use your windscreen wipers and demisters
• beware of other drivers not using headlights
• not accelerate to get away from a vehicle which is too close behind you
• check your mirrors before you slow down. Then use your brakes so that your brake lights warn drivers behind you that you are slowing down
• stop in the correct position at a junction with limited visibility and listen for traffic. When you are sure it is safe to emerge, do so positively and do not hesitate in a position that puts you directly in the path of approaching vehicles.

Rule 236

You MUST NOT use front or rear fog lights unless visibility is seriously reduced as they dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves.

When should you use fog lights?

You should only use fog lights when visibility is severely reduced. This tends to be below 100 metres - roughly the length of a football pitch. Fog lights are designed to cut through fog, mist and dust so other drivers can see your vehicle sooner. You shouldn’t use your fog lights when it’s raining but visibility is clear.

Bear in mind that Section 27 of the Road Vehicles Lighting Regulations 1989 states fog lamps cannot be used to dazzle or discomfort anyone else using the road. If you find yourself in an accident when conditions determine you should have had your fog lights switched on, you could end up invalidating your insurance.

When should you turn off fog lights?

Once the visibility has improved beyond 100 metres, you must switch off your fog lights immediately. This will help you avoid dazzling other drivers, obscuring your brake lights and potentially landing yourself a fine. This applies to both front and rear fog lights.

How do I turn on fog lights?

You’ll find your fog light controls either on your dashboard, steering wheel, headlight controls or even the infotainment system in more modern vehicles. The location will depend on the make and model of your car so please refer to your vehicle manual.

All vehicles must have at least one rear fog light fitted (either to the centre or offside rear of the vehicle) by law, while front fog lights are optional. Rear fog lights are much brighter than regular headlights.

Front fog lights

The front fog light symbol points to the left with lines pointing down diagonally. This is normally green, if fitted.

Rear fog lights

The rear fog light symbol points in the opposite direction with lines pointing horizontally. This is usually amber or yellow, if fitted.

Driving safely in fog

As referenced earlier, The Highway Code has guidelines for driving safely in foggy conditions, but here’s a recap:

• Reduce your speed - Slow and steady can help you stay safe if you can’t see what coming up ahead.
• Keep your distance - You should increase the stopping distance between you and the car in front when driving in adverse conditions.
• Don’t touch that full beam dial - This will only reflect off the fog and make visibility worse for both you and other road users.
• Use your demister - Demisting your windscreen can help you see clearer, especially if you have fog lights on.
• Stop in the correct position - If you’re coming up to a junction or traffic light, leave plenty of space between you and the car in front.

If visibility is extremely poor, even with your fog lights, National Highways recommends winding down your windows at junctions and crossroads to listen out for approaching traffic.

You could also stop in a safe place. Maybe a nearby services station where you can grab a coffee and a bite to eat while you wait for things to clear up?

Why is it dangerous to leave rear fog lights on?

The intense glare of rear fog lights can dazzle drivers behind you. The fog lights can also potentially be confused with brake lights, leading to other drivers thinking you're slowing down. To help avoid the chance of an accident, turn your rear fog lights off as soon as visibility returns.

How are fog lights different from regular headlights?

Fog lights work as they have a very focused beam that minimises the amount of light scatter that passes through fog particles, while regular headlights reflect off droplets of fog and shine back into the driver’s view.

Fog lights are mounted low to the ground and have a wider, flat beam that shines under the fog to offer better visibility than regular lights..

When it comes to MOT tests, your car will fail if the fog lights are not working. Make sure you regularly check and maintain them over the year to avoid a nasty surprise during your test.

Do all cars have fog lights?

Daytime running lights have replaced fog lights on some newer vehicles. These are permanently turned on and designed to make your car more visible but cannot solely be relied on in foggy or misty conditions.

You should always be prepared to drive in different weather conditions. Adapt your driving to suit the conditions and keep you and others on the road safe. Make sure you’re familiar with your fog lights and how they work. Always keep in mind the 100-metre rule while driving in the fog or mist.

If you are not confident and want someone else to take over the wheel, you could consider temporary car insurance. This lets someone else drive with fully comprehensive cover - not affecting your no claims discount in the process.

Sources

https://www.legislation.gov.uk/uksi/1989/1796/regulation/27

https://www.gov.uk/guidance/the-highway-code/driving-in-adverse-weather-conditions-226-to-237

https://www.traffic.gov.scot/driving-in-fog

https://www.highwaycodeuk.co.uk/fog.html

https://www.rac.co.uk/drive/advice/winter-driving/safe-driving-in-fog/

https://blog.halfords.com/driving-in-fog-when-to-use-fog-lights/

https://nationalhighways.co.uk/road-safety/travelling-in-severe-weather/travelling-in-fog/