Ok, managed to get it working 🙂
I’ve set it up like this…
3 pin plug into a socket in the garage leads into a 12V LED driver (£14) with 1.5mm 2 core and earth cable.
+ve output from the LED Driver goes into a Normally Open/Normally Closed Reed Switch (£9) which is mounted at the side of the garage door. From the reed switch is a cable running through a hole I drilled in my garage wall with an SDS drill and a long 10mm bit, across the hall and into the back of the lounge light switch to the LED which has a built in resistor (£5.50 for 5). I drilled a hole in the light switch face plate and mounted the red LED into a holder (£6 for 5) in the hole I made in the switch plate then connected the LED back to the -ve terminal on the LED Driver.
Now as soon as my garage opens, the LED lights up red, the moment the door fully shuts, the LED goes off. Really pleased with it.
I’m thinking of improving it.
1. I’ll remove the 3 pin plug and connect it to my garage light for power instead.
2. The LED not lit up could mean either of two things, it could mean the garage door is closed or it could mean something in the circuit has failed and the door could be wide open! The reed switch I bought was a NO/NC one which means it has 3 wires on it. I’m thinking of wiring up a green LED to the unused wire and mounting it in the same living room light switch so that when the door is closed the green LED will be on and when it’s open the red LED will be on. No LEDs on means circuit not working.
3. Also the LED holders I bought are little crappy black things you see in aftermarket LEDs fitted to car dashboard. I’ve seen some nice chrome ones which will match the light switch better.