Motion-Activated Floodlight
A PIR sensor switching a halogen floodlight. Unlike a plain switch, an active sensor needs its own live and neutral supply before it can switch anything at all.
Components Needed
Text Wiring Path
Live → MCB → PIR (L-in) Neutral → PIR (N-in) PIR (L-out) → Floodlight → Neutral
Schematic
Steps
- 1Place Live and Neutral, an MCB, a PIR sensor and a floodlight.
- 2Feed the sensor itself: Live through the MCB into L-in, Neutral into N-in.
- 3Take the switched L-out from the sensor to the floodlight.
- 4Return the floodlight's neutral directly to the supply.
- 5Press Run, then toggle the sensor contact to compare detected and idle states.
- 6Open the sensor's supply neutral in the Fault Lab — with no reference, it cannot switch.
A passive switch intercepts one conductor; an active sensor is a small appliance with a switched output. That is why PIRs want a neutral at the switch position, and why retrofitting one into an old two-core switch drop is a wiring problem rather than a straight swap.
These walkthroughs teach wiring logic in a simulator. Real installation work must be isolated, tested dead, and carried out by a competent person — in the UK, notified under Part P or done by a registered electrician.
Terms used here
Defined in the glossary — each one opens at its own entry.
Now wire it for real.
Build this circuit in the browser, inject a fault, and watch the protection respond.