A few facts on lights

I enjoyed reading the recent column (Jon K. Rust, "New lights brighten up Broadway streetscape) regarding the downtown street lighting and wanted to provide some basic lighting information.

The Illuminating Engineering Society or IES is considered the professional source for lighting information. The IES establishes the recommended footcandle standards for interior and exterior situations that include street lighting. For street lighting such as the downtown area the generally accepted footcandle recommended level is 1 fc. Most municipalities and state highway departments include footcandle requirements within their lighting design specifications.

A good lighting layout will evaluate several items to meet the footcandle requirements. When determining the most effective lighting layout the lighting professional will evaluate the fixture type including mounting heights, and spacing. The lamp type evaluation will consider the color spectrum and efficacy. The uniqueness of LED lamps is their specific direction makes it ideal for task lighting.

After the recent re-lamping project everyone is noticing the brightness. This is often the case when installing new lamps regardless of the lamp type. In this situation, the selected new lamp is LED which should result in energy savings. However, all lamps regardless of the type will experience a phenomenon called lamp lumen depreciation that results in over time a lighting performance decrease. All lamps including LED's have a rated lifespan.

Finally, I wanted to point out a critical lighting practice. It is recommended that fixtures be cleaned at least once a year. The annual cleaning will remove any obstructions that could impact the overall lighting. It will not prevent lamp lumen depreciation but will maintain the fixture refractive capability.

Glenn (Skip) Smallwood, Jr. is a Cape Girardeau resident.