In built-up areas you can find lamp posts that are marked with red and white reflective signs. Those signs are an official traffic sign in Germany (no. 394). They are used on lamp posts to indicate that streetlight does not stay on all night which can be a measure used by cities and municipalities in order to save energy.
The sign can be applied in the shape of a rigid sign (size 70 mm x 150 mm) or as a reflective band around the lamp post (width 70 mm) which is the more commonly seen version. The red area has a width of 50 mm and the white stripes on top and bottom measure 10 mm each. The lamp post ring has to be applied at a height between 1.50 m and 1.80 m.
When parking your vehicle, it is therefore important to pay attention whether the lamp post is marked with the reflective sign and, if necessary, to switch on the parking lights during the dark hours. Non-compliance may result in a fine.
The times when street light is switched off may be indicated in the red area of the sign.