When are you allowed to switch on rear fog lamps?

In Germany, driving with rear fog lamps is regulated to ensure safety during low-visibility conditions. You are permitted to use rear fog lamps when visibility is significantly reduced, specifically when it is less than 50 meters due to fog. This regulation helps drivers behind you see your vehicle more clearly in poor conditions.

The reasoning behind choosing only the first option—fog reducing visibility to less than 50 meters—is that the rear fog lamp's primary purpose is to alert other drivers to your presence when visibility is severely impaired. Option two, which pertains to 100 meters, does not meet the established threshold for when fog lamps should be activated. Option three regarding heavy rain is not correct as rear fog lamps are typically not used during rain since reduced visibility can be caused by water on the road rather than the fog itself.

Therefore, understanding the specific conditions under which fog lamps should be activated is crucial for maintaining road safety and complying with German traffic laws.