I'm working on a home project where a microcontroller records time when outdoor lights are switched on/off. Outdoor lights are 220V activated by built in PIR sensor. They're located outdoors 20-30m from the controller board. I was thinking to put a reed switch next to power lines so that when lights are switched on reed switch is shorted and microcontroller is interrupted.
I've checked other topics where people use current transformers but that seems over complicated to me as I don't need exact current value but rather just on/off state. My aim is to keep it simple and robust. Now questions:
- What is minimum distance between different reed switch/power line combos?
- There are some relays on the same board that control loads. Would relay coil affect reed switch? How should I protect reed from unintentional activation?
- What would happen to reed switch if it's activated by AC generated magnetic field?