A PIR floodlight is a directional outdoor light with a passive infrared sensor that switches it on when someone moves within range and off again once the timer runs out. The twist with an aimed light is that you are setting up two things at once – where the beam lands and what the sensor watches – and on a house wall those are rarely the same spot.
Get both right and the drive, side passage or back door lights up as you reach it, not after you have fumbled for your keys in the dark.
Outdoor spotlights and floodlights with a PIR come in a few distinct layouts, and the right one depends on the wall you are fixing to:
Spike-mounted garden spots with sensors and solar units for sheds and gates also exist. If a fitting takes GU10 bulbs, check that the sensor copes with low LED loads; some relays leave low-wattage bulbs flickering or faintly glowing.
Compare lumens rather than watts – efficiency varies between fittings. As a rough guide, 10 W of LED gives 800–1000 lm and 50 W something like 4000–6000 lm. For a semi or detached house:
| Location | Light output | Sensor coverage | Fixing height | Colour |
|---|---|---|---|---|
| Front door or porch | about 600–1200 lm | 100–140°, 6–8 m | 2–2.5 m | 2700–3000 K |
| Side passage or garden gate | about 800–1500 lm | 90–120°, 6–10 m | 2–2.5 m | 3000–4000 K |
| Drive or garage front | about 1500–3000 lm | 140–180°, 10–12 m | 2.2–3 m | 3000–4000 K |
| Back garden or yard | about 2000–4000 lm | 180–240°, up to 12 m | 2.5–3 m | 4000 K |
Under a canopy IP44 is enough; on an open wall or post go for IP65. Very bright, cool 6000 K floodlights suit a workshop yard more than a family home. For high-output units aimed at large areas, see LED floodlights with motion sensor.
A PIR picks up changes in heat, and it is far better at spotting someone walking across its view than someone heading straight towards it. That is why a light fixed dead centre above the front door often reacts late. Mount it to one side of the path instead.
Wiring to the mains is a job for a qualified electrician working to BS 7671. In England and Wales a brand-new outdoor circuit is notifiable under Part P of the Building Regulations; swapping a like-for-like fitting usually is not.
A light that keeps tripping is usually seeing swaying shrubs, passing cars, cats or warm air from a vent. Turn the sensitivity down, re-aim the head or mask part of the lens with the shutters some models include. Once or twice a year wipe the lens with a soft cloth, clear cobwebs and check the seals; a loose cable gland is how most water gets in.
The LUX (photocell) control is set too high, so the sensor thinks it is dark enough to switch. Turn it towards the moon symbol or minimum. Also check that the sensor is not in permanent shade under an eave while the rest of the garden is bright.
A floodlight with a built-in PIR is wired like any fixed light: live to L, neutral to N, earth to the earth terminal. A separate PIR sits between the supply and the lamp – the supply goes in, the switched live comes out to the light. Any wall switch feeding the circuit must be left on.
A light that suddenly snaps on removes the cover of darkness and makes someone easy to see from the street or a neighbouring window, which is why motion-triggered lights are a common part of home security advice. It works best alongside good locks and clear sightlines; a light nobody can see from outside achieves little.
Many units have a manual override: switch the wall switch off and back on quickly and the light stays on, typically until dawn or for several hours. Switching off for a few seconds returns it to sensor mode. The exact sequence varies, so check the instructions.
Twin spots let you light two directions from one fixing point, such as a corner or a drive that bends. A single floodlight gives a wider, more even spread across one open area.
Most homes are well served by 8–12 m and an angle of 110–180°. More range is not always better – a sensor that reaches the road will switch on with every passing car.
If you are still deciding on the style of light itself – narrow spot, wide flood or spike light for the border – start with outdoor spot lights.
