Floodlights are a tremendously popular way of lighting outside areas, but shouldn’t be used this way when they are intended as security lighting. When it comes to security, lighting is much more effective if it illuminates the walls of a building, rather than the area around it.
Because floodlights provide good illumination over a wide area, they can allow to you to continue working for a while after natural light has failed. They can also let you set things up for the day if you have to leave before the sun comes up, without the need to carry a torch. For this kind of task the lights are naturally mounted so that their light is cast over as wide an area as possible, i.e. pointing away from the building they are mounted on.
People tend to think that linking this kind of lighting to PIRs (motion detectors) makes their property more secure, but in reality it just makes things easier for intruders. Thieves need light just as much as anyone else, and carrying a torch makes life more difficult for them, keeping one hand full and leaving them at greater risk of being seen.
If someone who shouldn’t be there is approaching your property at night, they will probably have watched the place to make sure that you’re away, or asleep. So the real risk for them isn’t that you will see them – it’s that they’ll be seen from nearby roadways or buildings.
To make intruders stand out like a sore thumb, don’t light the area around buildings. Instead, light the walls themselves using narrow-angle floods and a much lower wattage: 50W is plenty. This leaves intruders silhouetted against the property and highly visible from nearby, without giving them much useful illumination to work by. Doesn’t seem right? Check out this Campaign for Dark Skies page for more advice, and an interactive demonstration of how outward-facing floodlights render intruders near a building invisible.
Security lighting cannot in itself protect your property from intruders. For the best protection consider whether a dog or burglar alarm might be appropriate, take a good look at access points and general security measures, and make sure that your property has adequate insurance through a reputable firm such as Aviva.