What are rear fog lights?
We often overlook our rear fog lights, but they play a critical role in driving safely when visibility isn’t great. Rear fog lights are designed to provide a powerful and concentrated beam of red light that can penetrate fog and heavy rain, which will make your car visible to drivers behind you. Some cars are designed with one or 
two rear fog lights. However, only the light on the driver’s side is turned on to avoid confusion with brake lights.
If road visibility is extremely poor and your car doesn’t have rear fog lights, a driver behind you may not be able to see your car until it’s too late. You’ll also struggle to see cars in front of you if they also don’t have them. Without these rear fog lights, your chance of being involved in an accident will increase significantly during times of poor visibility.
Safety Tip #1 – Know when to turn your rear fog light on and off
These lights emit a very powerful beam, designed to pierce through poor visibility conditions. However, if the road is clear and you are using your fog lights, you 
could cause a safety hazard by potentially dazzling other drivers.
Remember: a rear fog light is not a styling bulb and must never be turned on simply to show it off. They’re a safety device that should be used ONLY during periods of low visibility such as heavy rain or fog. If you’re struggling to see a few feet ahead of you, other drivers won’t be able to see you either, and rear fog lights should be used to stay safe.
Also, it’s worth keeping in mind that during night time driving, your normal headlights and tail lights are enough to help you see and be seen. Only use your rear fog light if the weather is especially harsh.
Safety Tip #2 – Only keep the driver’s side light connected
Some cars come with two rear fog lights, but only one of them will be factory wired. So, if only one is wired up, why is there two on the car? Well, there could be a few potential reasons. Two could preserve the symmetry of the car, or it could simplify the manufacturing process by using the same chassis in any country. For example:
- In the USA, the left-side rear fog light will be wired
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If that same chassis is used for a car in the UK, the right-side fog light will be wired instead
You may be tempted to wire both rear fog lights, but we would not recommend this. If both are illuminated at the same time, other drivers may confuse them for brake lights as they both are red in colour. This could lead to the following safety problems:
- A car with a single rear fog light is assumed to be driving at a constant speed, but if it has two and both are illuminated, drivers may think the car is braking and will also start to brake
- Even if drivers behind you are able to determine you are using both rear fog lights, their powerful beam may obscure the actual brake lights, making it difficult to see when you start to brake
In other words, using a single rear fog light on the driver’s side avoids confusion for others and helps the fog light to achieve its function.
Things to remember...
Proper use of rear fog lights is an important part of driving responsibly. Remember, their goal is to help you be seen by other drivers when visibility is poor. The powerful beam of light they emit is unsuitable for use when driving in normal to mild weather conditions and can dazzle other drivers if not used correctly.
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