Types of Lighting

Generally, four types of lighting units are used for security-lighting systems: continuous, standby, movable (portable), and emergency.

• Continuous lighting is the most common security-lighting system. It consists of a series of fixed lights arranged to flood a given area continuously with overlapping cones of light during darkness. Usually, a 50 percent overlap is desirable so that if one lamp fails, the lamps on either side can fill in (although at a reduced level) for the failed unit. Two primary methods of using continuous lighting are glare projection and controlled lighting.
  
  
  • The glare projection security-lighting method is used when the glare of lights directed across the surrounding terrain will not be annoying (Remember, keep the neighbors on your side.) nor will it interfere with adjacent operations. It is a strong deterrent to a potential intruder because it makes it difficult to see inside the area.
    
    
  • Controlled lighting is best when it limits the width of the lighted strip outside the perimeter, such as along highways. In controlled lighting, the width of the lighted strip is controlled and adjusted to fit the particular need. This method of lighting may illuminate or silhouette employees.
    
    
• Standby lighting has a layout similar to continuous lighting. However, the lights are not lit continuously but are turned on (either automatically or manually) when suspicious activity is detected or suspected by the security force or alarm systems. Standby lighting also is referred to as “crash” lighting. It can have a devastating psychological effect on an attacker or intruder whose cover of darkness disappears suddenly.
  
  
• Movable lighting consists of manually operated, movable lights that may be lit during hours of darkness or only as needed. The system normally is used to supplement continuous or standby lighting. Movable lights often are mounted on telescoping poles on trailers that have their own power generation for maximum flexibility.
  
  
• Emergency lighting may duplicate any or all of the systems described above. Its use is limited to times of power failure or other emergencies when the normal system is inoperative. Emergency lighting depends on an alternative power source such as installed or portable generators or batteries. Most building codes require these types of lights inside commercial or public buildings. They must switch on automatically and must provide enough light to permit occupants to exit safely.