Security lighting works by removing the cover that someone approaching a property relies on, and by signalling that the property is attended. It fails when it is aimed badly, set too sensitively or so bright that it dazzles rather than reveals. Getting it right is mostly a matter of position, aim and sensor configuration, not wattage.
Where security lighting actually helps
The useful positions are approach routes and concealed areas: side gates, rear access paths, the space between a garage and a boundary, and any dark corner where someone could work unobserved. Lighting the front of a house that is already lit by a street lamp adds very little.
Walk the property after dark before deciding. The dark spots are rarely where people assume they are.
Sensor positioning and detection pattern
Passive infrared sensors detect movement across their field of view far better than movement directly towards them. Mounting a sensor to look along a path rather than down it dramatically improves reliable detection and reduces the sensitivity needed.
Typical mounting height is 2 to 2.5 metres. Higher reduces range and sensitivity; lower increases false triggers from animals and is easier to tamper with.
Stopping false triggers
Most nuisance triggering comes from a handful of causes, all of which are fixable without reducing genuine coverage.
- Sensor aimed at a road, so passing vehicles trigger it
- Heat sources in view: flues, vents, tumble dryer outlets
- Moving foliage in front of the sensor
- Sensitivity set to maximum by default
- Another light or sensor in the same field of view
Brightness, glare and colour
Very bright floods create deep shadow immediately beyond the beam and dazzle anyone looking towards them, including you and any camera. Moderate output, wider distribution and more than one fitting gives better usable visibility than a single powerful flood.
Around 3000K to 4000K is a reasonable range. Very cool white looks harsh and is more likely to prompt complaints from neighbours.
Integrating with cameras
If cameras are installed, lighting and camera positions must be planned together. A flood pointed near a camera lens washes the image out completely and can make footage useless. Light the scene from the side or from behind the camera, never into it.
Cameras with their own infrared illumination often do not need additional lighting at all, and adding a bright flood can actually degrade the image by forcing the camera between day and night modes repeatedly.
Controls and overrides
A manual override switch inside the house is genuinely useful: for working in the garden after dark, and for turning a misbehaving sensor off without standing on a ladder. Many sensor fittings support a switch based override sequence, but a dedicated switch is clearer.
Adjustable timers should be set to a short duration, typically one to three minutes. Long durations mean the light stays on continuously on a windy night.
Wiring and protection
Security lighting is an outdoor circuit and needs residual current protection, suitable cable, correct glanding and fittings with an appropriate ingress protection rating. Feeding it from a dedicated way at the board means a water ingress fault in a garden fitting does not take out indoor circuits.
Cheap sealed units that cannot be opened for maintenance are false economy. Choose fittings where the gland and lamp can be serviced.
Neighbours and nuisance
Persistent light spill into a neighbour's window can amount to a nuisance and is worth avoiding on ordinary good neighbour grounds regardless. Shield the fitting, aim it down and stand in the neighbour's garden to check the result. Five minutes of that saves a long running dispute.
Setting up on the day
Commissioning is where most security lighting is won or lost. The sensor should be walk tested after dark across every approach it is meant to cover, sensitivity reduced until casual traffic no longer triggers it, and the timer set to a short duration. Aim and range are then locked off. A fitting that is screwed to a wall and left on factory settings will almost always need adjusting within a fortnight.
Common questions
- Why does my security light keep coming on?
- Usually the sensor is aimed at a road, a heat source or moving foliage, or sensitivity is set too high.
- How high should a sensor be mounted?
- Around 2 to 2.5 metres, aimed across approach routes rather than straight down them.
- Is brighter better?
- No. Very bright floods create glare and deep shadow. Moderate, well distributed light is more useful.
- Will it interfere with my cameras?
- It can, if aimed towards the lens. Light from the side or from behind the camera instead.
- Can I switch it off manually?
- Yes, with an indoor override switch, which we recommend fitting at installation.
- How long should the light stay on for?
- One to three minutes is usually right. Longer settings mean the light stays on almost continuously on a breezy night with moving foliage in view.
We install and aim security lighting properly, including override switching. Ask for a security lighting quote.
Related guides
- Garden Lighting Installation: A Practical GuideA garden lit well uses fewer fittings, aimed lower, than most people expect.
- Planning Outdoor and Garden LightingGood exterior lighting is mostly about restraint, direction and IP ratings.
- Outdoor Sockets and Garden Lighting That TripGarden electrics live outdoors, and outdoors is where every weakness in an installation eventually shows.