Replacing a Light Switch
On all switches, you are going to have three wires. One is a ground, just disconnect that one. Now the other two are the hot leads. One of those wires supplies the light or outlet with the power and the other black lead is supplying the switch with the power. Simple right? yes, it is. To make a connection with wire they need to touch, well that’s what the switch does for us over and over again.
Just remember to make nice clean and tight connections with the screws to the wires and you’ll be a pro.
You can never tell what gauge wire you’re going to have in your house until you’re there doing it. So 14 gauge wire is 15 amps and a 12 gauge wire is 20 amps. And yes they make switches for either one. So make sure you don’t install a 15 amp switch where you really need a 20 amp. A rule to go by is. If you have one or two lights on that one switch, then a 15 amp is good. But if you have a lot of lights on that one switch I would just go with a 20 amp switch to be safe.