Some of these data are from the International Dark Sky Association. This is an excellent organization and is strongly supported by Tamke-Allan Observatory at Roane State Community College.

The unshielded fixture shown at the left, especially with a Mercury Vapor Lamp should NEVER be used. It wastes light that should be kept on the ground. It causes glare that makes it more difficult to see nearby objects and can actually reduce security because of the glare that it produces. It causes light pollution over a wide area. Shields can be added (make your own or buy one like those shown below) to direct the light downward and save light.

Rockwood Electric Utility currently supplies 175 watt mercury vapor fixtures for home security lighting and 400 watt fixtures for street lighting. We are asking them to choose to install well-designed light-saving fixtures (that direct light downward) and to choose Sodium vapor lighting instead of Mercury vapor. Many homes would welcome a smaller fixture -- for example, 70 watt.

In reviewing dark sky-friendly fixtures that may be useful for homes in east Tennessee, two fixtures stand out, the GE SKYGARD 201AS and the American Electric Lighting because they are avaliable with 70W HPS (high-pressure sodium) lamps. Even 70W HPS can be excessive for residential use.

Related Links (also see shields below):  Shields & Mods and Motion Sensor