How Long is a Piece of String?

How Long is a Piece of String?

In electronics the term of service is always an important issue. But nowadays many devices become obsolete before the end of the life-span. Lighting is an exception. Light bulb isn't the kind of device we tend to change before it burns out.

Lighting market offers a lot of options so it can be quite difficult to make a choice. So let’s have a closer look on each of lighting technologies and their properties.

Incandescent light bulbs

The oldest and still one of the most popular lighting technologies. The rated lifespan of incandescent light bulb is about 1 200 hours. But only in perfect conditions. In fact, the voltage fluctuations and start up current damage the filament and cut down the life-span even more.

Fluorescent lamps

CFL or fluorescent light bulbs promise up to 10 000 hours of service. But it’s not so simple either. There are two elements of CFL construction that can substantially decrease its lifetime: capacitors and gas ballast. If the capacitor of fluorescent lamp is constantly overloaded because of old wiring or voltage fluctuations it goes off faster. The gas density also falls with time and, as a result, the light becomes dimmer.

LED lamps

Light-emitting diodes have a rated lifespan over 50 000 hours. But it is quite difficult to define it as LED lamps do not burn out. They just start to fade out. The life-span of LED's is measured by L70 standard or the point when a LED lamp starts emitting only 70% of initial light.


Comparison chart of different light technologies

  LED CFL Incandescent
Light bulb projected lifespan, hours

50 000

10 000   


Watts per bulb (equiv. 40 watts) 4 14   40

KWh of electricity used over 50,000 hours

200 700 2000
Bulbs needed for 50k hours of use 1 5 42


As you can see, LED lamps not only consume less electricity but also serve for much longer.

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