would this cause an issue?
issue with what ?what kind of issue ?
I still think replacing the led with an opto-coupler would allow you to put everything under software control instead of requiring a human to view a led.
More likely Needs a pullup resistor.
o correct me if I'm wrong, on the LED side in replacement of the neutral your using the earth?
so the LED is staying in the same place?
Scenario A : (no arduino) => thus , no opto coupler
Scenario B : You decide to ADD an arduino to detect loss of mains power and send an RF signal somewhere or send an SMS text message or send an message by internet, then my last reply applies as is .