Security lights are needed to protect buildings and facilities from break- ins and vandalism at night as well as to let pedestrians see where they are going and to help to keep them safe from attackers. Security lighting is an important aspect of any security installation as it makes it possible to spot intruders or suspicious activity and makes it harder for people to hide in the shadows.
You would expect that when it comes to security lighting, the more light, the better, but this is not the case. Sometimes over lighting a location can actually increase its chances of being targeted by criminals and if the area is too harshly lit, then you get glare, which can be as bad as under lighting for being able to identify details or movement. Another aspect is that when there is too much light, you get even darker shaded areas that criminals can hide in. What is needed is just the right amount of lighting, and in the right places.
Lighting installations cost a lot to buy, maintain and the electricity demands can be high not to mention the environmental light pollution, so this is something that needs careful thought and planning. Light overspill to neighbouring areas can be a problem so horizontal lighting has its limits but overhead lighting does too as it is only effective when spread over large areas meaning high wattage units are needed, if the lighting is too bright, you have the problem of glare.
In many locations the most effective security lighting is a combination of halogen and sodium lights in a carefully chosen locations and orientations. You get the best lighting when the light from two or more lighting units overlap, then you get the least amount of shadow. The ones that are not needed for walkways and to illuminate entrances can often be connected to movement sensors which save power and are very effective at deterring intruders, who will often be unaware of them being there until they are activated.
As security lighting installations are often vandalized either for no good reason or part of a determined break in attempt, they need to be protected by anti- vandal measures, mounted very high up, surrounded by razor wire or made from toughened materials. They are often mounted in recessed areas with toughened glass in front of them and they are at their most effective when used in enclosed areas in fairly high numbers.
Newer low power longer lasting LED lighting units are becoming available, which offer features like being dimmable and power up faster than traditional sodium and halogen bulbs, they give the best lighting for colour rendering as well, which will produce higher definition video images for security cameras and allow people to see where they are going better.