230V will go thru relay contacts - but relay coil will only see 5V. So measure the coil, see if it is energized or not.
Here's a circuit to let a wall switch turn a relay on or off.
Momentary button/switch turns on light, arduino senses it & keeps it on for some time amount, turns it off after some interval, can be commanded remotely to turn it off as well.
Suppose the switch could just be an arduino input as well, toggle/rocker switch, read the level and turn light on/off, and still turn it off after a time interval.
