Security Light Not Coming On

What is this?

PIR (Passive Infrared) security lights detect body heat and movement to trigger illumination. When they stop working, the fault is usually with the PIR sensor, the bulb, the electrical supply, or the settings. Most UK homes have at least one PIR security light above a doorway or driveway.

Common causes

• PIR sensor has failed or become misaligned
• Bulb has blown (especially halogen floodlights which have a shorter lifespan)
• Sensitivity or range setting turned too low
• Timer set to a very short duration so the light appears not to work
• Spider webs or dirt covering the PIR sensor lens

Is it dangerous?

A non-working security light is not an electrical danger, but it is a security risk. A dark entrance or driveway makes your home more vulnerable to break-ins and increases the risk of trips and falls.

Can I fix it myself?

Start with the obvious: check and replace the bulb. Clean the PIR sensor lens with a damp cloth to remove dirt, cobwebs, and insects. Check the sensitivity and timer dials on the light (usually small adjustable knobs on the unit). Make sure the range setting is not set to minimum and the timer is not set to the shortest duration. Some PIR lights have a manual override — check if it has been switched to the off position.

When to call an electrician

Call an electrician if the bulb is fine and the sensor appears clean but the light still does not work, if the light has power but the PIR sensor has failed, or if you want to upgrade to a modern LED security light. If the light is hard-wired (not plug-in), any replacement work should be done by an electrician.

What will an electrician do?

Typical cost