connecting to the light
What is the gang, and what is the way？
This is important knowledge because it affects the number of switches you need to buy.
Gang: the gang is the number of buttons on the light switch. The 1gang light switch has only one button. 2 gang lighting switch has two buttons, and so on, three gangs, three buttons, four gangs, four buttons.
And there are several gangs, which means that several wires can be connected behind, 1gang can control one line, and 2gang can control two lines.
Way: The way is the control method of the switch; 1way means that a switch can only control one line. And 2way means that two switches can control the same line.
For example, if you want to turn off the same light upstairs and downstairs, you need two 2way switches to achieve this function.