Service life of illuminants
The service life of illuminants is usually expressed in hours. There are two different methods to determine this value: the average service life and the useful life.
In the case of conventional incandescent lamps, halogen lamps, low-voltage halogen lamps as well as energy-saving lamps with an electronic ballast, the average service life is indicated. It describes the time period, in which 50 per cent of the illuminants in a lighting installation fail.
The case is different with the useful life. It is used to rate the service life of LEDs,fluorescent lamps and compact fluorescent lamps with a plug-in base as well as high-pressure discharge lamps. This figure indicates after which time period the luminous flux of an illuminant has dropped to a specified value. It is indicated by means of the L value: a service life of L70 thereby describes the time period after which the illuminant only produces 70% of its brightness. The L70 value is the most common method of describing the useful life of an illuminant. However, sometimes other values are specified, for instance, L50.
Whether the average service life or the useful life are used as a basis – all data specified must be considered as mean values, i.e. this is an average specification and it does in no case present a guarantee that an illuminant will at least achieve this service life. There are lamps that cease to function before the end of the average service life, others supply a significantly lower luminous flux before the end of the useful life. However, the opposite scenario is also possible: some lights might be used for a significantly longer period of time than you would have expected based on the service life specified.
The service life of illuminants is of particular importance where the lamp replacement is rather complex, e.g. in the case of splash-proof bathroom lights or exterior lights. Exchanging the illuminant of ceiling lights in rooms with high ceilings might also be quite complicated. Whenever an electrician is needed to replace the lamp, the service life also plays an important role. With regard to the respective areas of application, it is recommended to make sure that the illuminant has a possibly long service life.
Benefits for the environment & your budget
With regard to the economic viability of home lighting it is also best to consider the service life of illuminants prior to the purchase. While conventional incandescent lamps cease to function after only about 1,000 hours of operation, modern LED lamps have a service life of 50,000 hours or more. If you not only consider the long service life but also the low energy consumption of efficient LEDs or energy-saving lamps, you will see that the higher purchase costs will be amortised after a short period of time. A further advantage is: less waste and consequently a reduced impact on the environment.
The following table provides a comparison of the service life of various illuminants.
Service life (operating period 3h/day)
20,000 – 50,000 h
20 - 50 years
12 V eco halogen lamps
2,000 – 4,000 h
2 - 4 years
230V eco halogen lamps
2 000 – 4 000 h
2 - 4 years
In order to be able to also compare all other important characteristics, we prepared an overview table of all common illuminants, which is available here