The hot wire in a volt residential AC circuit usually is coated with black insulation, while the return, or neutral, wire is white. A single-pole, single-throw switch — such as a light switch — works by interrupting the hot wire, so it has two brass terminals for the hot connections and no silver terminals for neutral. Hooking up a switch is the essence of simplicity.
Homeowners may choose to replace or upgrade a light switch for functional or for aesthetic reasons. Changing the light switch is a simple and inexpensive DIY project. Understanding how the switch is wired is the most important part.
Now in the diagram above, The power source is coming in from the left. Notice the black wire is the only wire that we are controlling through the 2-way switch. You have an incoming hot wire black going to one screw it does not matter if you use the brass or silver screw on the side of the 2-way switch and a black wire from the other screw on the 2-way switch going to the load light, ceiling fan etc.
Here's how to swap outdated three-way light switches for something much better. Don't put up with old three-way light switches like this. Swap them out for something new and improved.
If a light switch fails to function, it should be replaced. Most modern switches have screw terminals on each side and may also have holes in the back to accept the end of the wire. You can easily loosen the screws on the side of the device with a standard screwdriver turning counterclockwisebut you may find getting the wires out of the back of the device tricky.
Power to the switch. Pow er from the lights. First of all we should connect the ground wires to the box. If the light switch has a ground screw on it usually green and at the bottom of the switchconnect it now.
It isn't unusual to wire two or more light and switch combinations from the same power source -- in fact, it's common practice. Typically, the source is a circuit breaker in the main electrical panel that has a rating large enough to handle the lights. It's possible to mount the switches in the same or in different electrical boxes, but the latter case involves the extra task of running a circuit cable between the boxes.
A simple single-pole light switch will run you just a few bucks, making it one of the least expensive building components to replace. So if you have switches that are old and discolored, were broken by someone moving a heavy piece of furniture, or are just plain worn out, then there's no reason not to fix them. The swap-out takes only 15 minutes and you can handle the job even if you've never done basic electrical work before. Turn off the electrical circuit where you plan to work by throwing the appropriate switch on the circuit breaker.