Optimum operating voltage for long service life and optimum efficiency

OSRAM halogen lamps are designed for optimum operating voltage. This means that at this point, the perfect light current relative to the input energy is reached. At a higher voltage or when the lamp is dimmer, the service life or the efficiency of the lamp worsen considerably. Even changes of just a few percent in the operating voltage are sufficient to reduce the lamp efficiency significantly.

Higher voltage: more light, shorter service life

When the specified operating voltage is exceeded, halogen lamps produce more light but their service life falls considerably. When the voltage actually used exceeds the optimum operating voltage by even just five percent, the service life falls by 40 %. Thus 230 Volt halogen lamps, commonly used in Germany, should not, for example, be used in Great Britain, where 240 V is used. Increased luminous efficiency is also possible at a higher voltage. Therefore halogen lamps should only be used in the specified voltage range, in order to achieve optimum results.

Dimming: less efficiency, increased service life

Halogen lamps are often dimmed to create atmospheric lighting. The lower operating voltage increases the lamp's service life. In such scenarios, the efficiency of the halogen lamps, achieved at the optimum operating voltage, is reduced considerably. The reasons are as follows: Continuous dimming to a lower light level does not lead to an expected energy saving. Therefore, if lamps are continually dimmed, they should be changed over to a lower wattage.


In order to achieve the best possible characteristic lamp values with regard to service life, luminous efficiency and efficiency, OSRAM halogen lamps should be operated at the optimum operating voltage. This is advantageous all-round, not just for economic reasons.