Switch the light off at the wall switch and leave it off for at least 60 seconds. That gives the sensor's capacitor time to discharge and clears whatever mode the light was left in, including manual override. Switch it back on and the light should return to normal sensor operation, though some models run a short warm up first. If nothing changes, turn the lighting circuit off at the switchboard for a full minute and try again. Odd behaviour is often a mode that needs clearing rather than a fault.

There are four common causes. First, the light has been left in manual override mode, so switch it off at the wall and leave it off for about a minute to return it to sensor mode. Second, the LUX dial is set toward the sun symbol, which lets the sensor trigger in daylight as well as at night, so turn it toward the moon symbol. Third, the TIME dial is near maximum, which can hold the light on for up to about 15 minutes after every movement, so wind it back. Fourth, dust and cobwebs on the sensor lens cause constant false triggers, so wipe the lens gently while you are there.

Most sensor lights have a manual override you trigger from the wall switch. Flick the switch off then on in quick succession, commonly off, on, off, on, and the light stays on permanently until you switch it off and leave it off for about a minute to return to sensor mode. The exact number of flicks varies by brand, so check the instruction manual for your model. Override is useful when you are working outside after dark, but forgetting to clear it is a common reason people think their sensor light has failed.

LUX sets how dark it has to be before the sensor will trigger. A sun symbol means the light will also work in daylight and a moon symbol means night only. TIME sets how long the light stays on after the last movement it detects, typically anywhere from about 10 seconds to 15 minutes depending on the model. SENS, sometimes marked RANGE, sets how far away and how readily the sensor picks up movement. If passing cars or pets keep setting the light off, turn SENS down, and if your model has an adjustable sensor head, re-aim it away from the street.

The first digit of an IP rating covers solids such as dust and the second covers water. IP44 is enough for a covered spot like a porch, patio or carport where the fitting is shielded from direct rain. IP65 is the right choice for a fully exposed wall, an open yard or a driveway. Near the coast, treat IP65 as the minimum and also check the material, because an IP rating covers dust and water but not salt corrosion, so look for 316 stainless steel or a marine rated finish. If you are unsure outdoors, go up rather than down, and our IP rating guide on the blog explains the full scale digit by digit.

As a guide, 300 to 800 lumens is enough for a doorway or porch, 800 to 2,000 lumens suits a driveway, carport or side path, and 2,000 lumens and above covers a whole backyard or a long driveway, usually with a twin head flood light. Colour temperature matters too. Warm white around 3000K suits entries and outdoor living areas, while 4000K to 5000K reads as brighter and is the usual choice for security. Brighter is not always better, because a high output flood light aimed at a neighbouring window causes glare complaints.