How to Wiring Smart light Switch? Neutral line and Fire Line Choices.
The important thing to buy a Smart Switch is to notice whether it need Neutral Line, and this depends on whether your home have the neutural line for the light you want to control.
So first of all, you need to be sure the name of lines in the responding switch button:
You could use the electrical pen to test the line, if it's lighten on the pen, then the line is fire line, and fire line is usually red;
Them you could distinguish the neutral line by the below way:
So the above is for the wiring choice of smart switch for your reference, hope that could help. And if there is any problem please don't hesitate to contact us.