LED fixtures rarely break down; they slowly degrade. That is why a lifespan rating includes a code: the L indicates how much light remains at that point, and the B indicates how many fixtures are allowed to fall below that level.
If it says “100,000 hours” without a code, there’s no way to tell whether that refers to the 90% light output or the 70%, or whether it applies to all fixtures or just half of them. Below is an explanation of what the two letters mean, why the LB value determines your maintenance factor, and what we’ve concluded.
Our DarkLicht series is available at 103,500 hours, L90B05. At 4,000 operating hours per year, it will take well over 25 years before the luminous flux falls below 90%.
The code is never separate from a statement of operating hours: L90B05 at 50,000 hours is a different promise than L90B05 at 100,000 hours. But at the same number of hours, the code makes all the difference.
An LB value is not an off-the-cuff promise. It comes from a measurement on the LED modules over thousands of operating hours, after which the series is extrapolated to the specified lifespan according to a fixed method. The measurement standard is called LM-80, and the calculation method is TM-21.
This also says something about the limits of such figures: it is a well-founded extrapolation of the LED’s lumen depreciation, not a guarantee that the fixture will still be working after 103,500 hours. The driver, the seal, and the housing are the determining factors for the latter.
In practice, the LED is rarely the component that fails first. That is usually the driver, or the ingress of moisture.
How moisture gets into a luminaire that is sealed on paper is discussed in the article about IP and IK classification.
Standards require a light level as a maintained value: the level must also be achieved at the end of the maintenance period. Therefore, a lighting calculation uses a maintenance factor, and that factor comes directly from the LLMF value and the depreciation.
An example with simplified assumptions: the same 24,000 m² at 50 lux, the same maintenance factor, only a different luminous flux maintenance over the maintenance period. The factor that you actually apply is agreed upon in advance and results from the environment, the cleaning regime, and the chosen period.
Anyone who asks for 50 lux without specifying whether it is an initial value or a maintained value will get the cheapest offer: initial value, with fewer luminaires, which falls below the standard in year four. That is not fraud; it is a specification that did not ask the question.
Therefore, write down three things: the light level, that it is a maintained value, and the maintenance factor with the period to which it applies. Then you compare offers on the same basis.
And request the maintenance factor (MF) value of what you are purchasing. Without that code, a maintenance factor is an assumption rather than a calculation.
Everything we supply is rated at L90B05: the strictest of the common standards. The difference in hours between the series comes from the thermal design and the operating range of the luminaire, not from a different measurement method.
The 360,000 hours of the floodlights and work lamps do not apply to the area lights, and vice versa: never use one value for the other product. The datasheet lists the specification per version, including the code, which you can download without a form.
A lifespan specification is a technical expectation, a warranty is an agreement. They have nothing to do with each other, and that is precisely where confusion arises in proposals.
Backed by a measurement on the LED modules and a fixed calculation method, but it remains an extrapolation. It does not state that the luminaire will still work after those hours; it states how much light it will still emit if it works.
That says what happens if something breaks, within what timeframe, and under what conditions. A long lifespan specification without a warranty is therefore just a nice number without a story, and a long warranty with conditions that nobody reads is too.
Just the fixture, or the driver as well? Replacement, or just the delivery of a part? And who climbs the pole? At a height of sixteen meters, the cherry picker is more expensive than the fixture, and that is often not covered by the warranty.
Extensions to ten, fifteen, or twenty years almost always come with strings attached: a maintenance contract, a registration, or a maximum number of operating hours. Ask for that condition, because that is where the promise holds true or not.
Five years on the complete luminaire. As long as a maintenance contract is in effect with us or with a party designated by us, we extend the warranty on the housing to ten years. For the fully 316L version, twenty years apply to the housing and five years to the remaining parts.
We never write just “ten-year warranty.” That is a promise that won't be honored in the event of a claim, and then it would have been useless to you.
Chip efficiency versus system efficiency, and the impact on the payback period.
What the codes guarantee, and the five things they do not cover.
Why more lumens does not mean more light on the ground.
All subjects together are on subsidy and knowledge base.
If you are comparing two offers and one of them does not have an LB code, please request it. We can calculate what the difference in luminaires and maintenance factor means upon request.
The L stands for the luminous flux remaining after the specified number of hours: L90 means at least 90% of the original luminous flux. The B stands for the percentage of luminaires that may fall below that level: B05 means a maximum of 5%. Thus, for L90B05, 95% of the luminaires will still provide at least 90% of light after those hours.
For the same number of hours, L70B50 is a much weaker guarantee: 70% luminous flux, with half of the fixtures allowed to fall below that level. Historically, L70B50 was the standard way to define service life; L90B05 is the most stringent of the common codes and the standard we adhere to.
Because omitting the code makes the number seem larger. Without the LB code, it’s impossible to tell whether those 100,000 hours correspond to the 90% luminous flux or the 70%, and whether that applies to all fixtures or just half of them. Request the code, or do not use the number in a comparison.
The rated life is 103,500 hours for L90B05. At 4,000 operating hours per year—which is typical for a site with twilight switching—that’s well over 25 years before the luminous flux falls below the 90% threshold. For a sports field with 500 operating hours per year, this takes even longer, and in that case, other components determine the practical service life.
Based on a measurement of the luminous flux depreciation of the LED modules over thousands of operating hours, according to the LM-80 measurement standard, which is extrapolated to the specified lifespan using the TM-21 calculation method. It is therefore a substantiated extrapolation and not a guarantee that the luminaire will still function after those hours.
No. That value applies to floodlights and work lights. For the DarkLicht floodlights, which are installed on grounds and sports fields, the rating is 103,500 hours at L90B05. Never use one value for another product; this is a mistake that frequently appears in datasheets and on websites.
Standards require a light level as a maintained value: the level must also be achieved at the end of the maintenance period. The maintenance factor is the product of the luminous flux maintenance and the depreciation. A lower LB value means a lower factor, so more lumens are needed upon delivery, and therefore more fixtures. This is how the code impacts the price.
Seldom the LED. Usually the driver, or moisture gets inside. Our AC drivers have a rating of more than 130,000 hours; how moisture gets into a luminaire that is sealed on paper is explained in the article on IP and IK classification.
No. A lifetime rating is a technical expectation, a warranty is an agreement on what happens if something breaks. We provide five years on the complete luminaire, and as long as there is a maintenance contract in place with us or a party designated by us, we extend the warranty on the housing to ten years. For the fully 316L version, that is twenty years on the housing and five years on the other components.
Because the extension to ten years is subject to a condition: a current maintenance contract with us or with a party designated by us, and it applies to the housing. Simply writing “10-year warranty” is a promise that will not be honored in the event of a claim, and then it will have done you no good.
Every lighting calculation you receive from us specifies the maintenance factor and the period used. Free of charge, and a response from an engineer within one business day.