Important
Never touch the glass part of the bulbs with your fingers. Grease from your fingers is vaporised by the heat, coating the reflector and then causing damage.
Note
Outside lighting such as headlamps and rear lamps may temporarily have condensation on the inside of the lens. This is normal and all exterior lighting is designed to withstand this. Condensation is normally vented out of the lamp housing when the lamp has been switched on for a time.