Unlike conventional light sources that can (and often do) fail suddenly and unexpectedly, the light intensity of LED light bulbs reduces gradually over a period of time. This is known as Lumen Maintenance. Read on to find out exactly what it is.
Therefore, with the advent of LED lighting, it became necessary for the lighting industry to devise a wholly new standard by which to measure their gradual depreciation.
Slightly confusingly, the testing methods for other types of light source all have quite similar nomenclature and coding which is as follows:
Incandescent light bulbs having an LM-49 designation;
CFLs or “Compact Fluorescent Lamps” are LM-65;
LED light sources have the LM-80 test.
The “LM” part of the label stands for Lumen Maintenance.
While more traditional light sources have their mean time to failure tested, LED bulbs are tested by something called their lumen maintenance life.
Lumen Maintenance Is…
As stated earlier, LEDs gradually lose their lumen intensity over a prolonged period of time. This process is known as “Lumen Depreciation” and it occurs due to the small amount of heat that’s generated at the +/- interface of the bulb. Combating this depreciation and prolonging the LED’s life is one of the problems developers solved by incorporating an effective heat sink in their bases. Thus, the latest LEDs like the GE LED Deco Globe 3.5W E14 that’s pictured can last up to 20 x longer than more traditional incandescent models.
Lumen Maintenance effectively measures the level of light generated by a bulb when it’s new in comparison with its output at a pre-designated moment in the future.
It’s expressed as the following equation:
“The Lp of χ hours, where the value of ‘L’ relates to the original light output and the ‘p’ denotes the % of light maintained over χ number of hours.” Now, is that clear???
If not, an example, if a light source is given an L70 rating of 10,000 hours, after 10,000 hours of constant use, its light intensity will have depreciated by 70%.
Why Is L70 Significant To LEDs?
Ascertaining the useful lifespan of an LED light bulb by the amount of illumination it emits raises a question about what constitutes an acceptable level? There will be many different answers to this, because it’s really a subjective thing – a preference that can depend upon many factors such as the user’s individual requirements. However, the L70 rating seeks to impose a standard by which the entire lighting industry measures its products.
The L70 label was introduced following research by the Alliance for Solid State Illumination Systems and Technologies. It discovered that humans noticed a depreciation in the lumens produced by a light source only when they fell by 30%. This obviously leaves 70% – hence L70.
Nowadays, high quality LED bulbs and spotlights will boast a far higher L70 rating than those that are less well-made, so ensure that you compare the L70 rating when you’re buying them!
Give Us A Call About Lumen Maintenance!
If you’d like any more information about Lumen Maintenance or LED lighting in general, please don’t hesitate to contact a member of our customer service team on 0116 262 5933 or send an email enquiry to firstname.lastname@example.org