Before diving straight into this topic let’s take a few moments to look at what we did in a pre-LED world and understand what we mean by ‘maintenance factor’ and how we apply it to sports lighting applications.
The illumination level referred to in most lighting standards is defined as a ‘maintained illuminance’ or ‘the lighting level below which the installation should not fall over its lifetime. If we use the example of local clubs playing in the same league/division, they will have equal and fair playing conditions from lighting systems having quality and longevity over time.

The light output of all lighting systems falls over time no matter the technology, due to depreciation/deterioration of equipment and components used to build lighting systems; light sources, optical systems, light emitting surfaces of luminaires, ballasts or drives, system supply voltage* and voltage drop* within an installation.

Some of the above losses are permanent while others are recoverable depending on luminaire construction and how light sources and optics are integrated. In the days of replaceable metal halide light sources, once the output of a lamp fell to a predicted level, we could simply replace it recover the light loss and continue this process over the entire life of the installation. Dirt build-up on the light-emitting surfaces can be removed by cleaning.

Typical metal halide systems could have a declared service life of 15,000 hours at which point lumen output may have fallen by 70% and at which point 50% of lamps may have failed due to electrical or mechanical issues.

*Voltage-related issues were of more concern when using magnetic control gear. Today this is less of an issue as electronic control gear is able to self-regulate.

October 2021
Authored by:   Michael Gorman

To contact the author please send messages to michael@michaelgormanlighting.com