As a rule, the analysis of light bulbs is part of an investigation following a traffic accident. It serves to establish whether the lights were switched on and whether brake lights or indicators had been fully operational.
Under no circumstances should any lights be switched on or off to check whether they are still in working order after an incident, as this would destroy the basis for any investigation. For analysis, the entire headlight unit should be supplied with the light bulb still inside, especially when the glass around the filament is shattered. If a light bulb is supplied undamaged and without the headlight, the front-facing side must be identified either by marker pen or sticker.
When preparing a headlight or light bulb for transport, care must be taken to ensure that no packing material or adhesive foil can come into contact with the light bulb filament.
The preferred mode of transport is by courier. This is because the filament is easily damaged, altered or broken by incorrect or careless handling, for example, on a conveyor belt, or if the package is dropped or thrown