Light switches certainly have a common appearance in the collective unconscious, but they do in fact come in a range of types, which vary by style and by functionality.
These tips will help you understand the different varieties of wall switches and how their installation processes differ from one another.
Working with wall and light switches means working with electricity. Always put your safety first and make sure the power supply for area you are working on is completely off in order to prevent shock injuries.
Types of Wall Switches
In most cases, all three types of switches can be interchanged. Meaning, no matter what you currently have installed, you can likely replace with a different type of switch.
Toggle switches are the kind of switch with an arrow-shaped armature that complete the circuit, thus powering the light. When flipped to the "on" position, the armature moves so that the circuit is complete and power can flow to the light. When it is moved to the "off" position, the armature moves in a way that breaks the circuit so that no further current is channeled into the light bulb.
Mercury switches are built with a cylinder that is partially filled with mercury. The "on" position floods the cylinder with mercury, completing the circuit and powering the light.
Silent switches are designed so that a steel spring is the moving mechanism that is switched to open or close the circuit.
The Single Pole Toggle Switch
This switch has two brass screws and two wires: a black wire that is the interrupted wire, and a white wire that receives a continuous supply of power.
As you connect the wires, take care that they go in the same direction that the screws tighten in.
If in your switch the wire is supposed to make a connection to the terminal screw before continuing, then you should apply a 6-inch piece of wire with a stripped end and put all three pieces together with a wire-nut. (Wire-nuts are good for splices.) Be sure to layer sections that have been soldered under insulating tape.
The basic rule is to connect white wires to the light attachments and black wires to the dark attachments. Attach ground wires to green screws.
Outside Main Wiring Run
At the light switch, connect the black wire to one terminal and the white wire to the other. Remember, a green screw is always for the ground wire.
In-line Switch to Control One Light
To install this type of arrangement, you must add a third wire, which is typically red in color, from the switch to the outlet where you control it. Set this up when you want to control the first electrical fixture with a switch while the power continues elsewhere.
Switch and Convenience Outlet in Same Box
Make sure the power is off. Attach the pigtail to the brass terminal, and then put a second pigtail onto your choice of terminals at the switch.
Wire-nut these two pigtails and the black wire from the light fixture together. Connect the white wire from the light fixture to the silver terminal on the outlet. Connect the red wire from the light fixture to the other terminal on the switch.
At the light fixture, wire-nut the white wires from the power source, the light fixture and the switch together. Wire-nut the black wires from the power source and the switch together. Wire-nut the red wire from the switch and the black wire from the light fixture together.
Two Parallel Switches for Control of Two Separate Lights
Connect the first pigtail to the switch box. Put the second pigtail on the switch of the other box, and connect the wires according to color code.
How 3-Way Switches Work
A three way switch works slightly different than those already mentioned. The first wire connects the light and the power source. Switches control the flow of power through a second wire. The point where the second wire connects to the first switch is referred to as the common terminal.
Light Control Beyond the Switches
Connect the white wires with a wire-nut. Likewise, you will connect the black wire from the light to the white wire of the switches.
Working at the first switch, attach the red wire. Connect the black wire to the terminals, and do so with the white wire as well.
Working from the second switch, find the three-way switch and connect the red wire. Connect the white wire from the first switch to one of the terminals. Connect the black wire to the only remaining fixture. Finally, connect the the black wire of the first switch to the white wire of the light.
Light Control Between Switches
Working at the first switch, locate the common terminal and connect the red wire. Then connect a white wire to a terminal and put a black wire on the only terminal left. Working at the second switch, connect the red wire to the common terminal, and put the white wire to a terminal. Do the same with a the black wire.
Working on the light fixture, you must first connect the red wires. Then attach the white ones with a wire-nut, as well as with the black wires and the wires connected to the power source.
Instructions on how to install a new light fixture
Information in this article has been furnished by the National Retail Hardware Association (NRHA) and associated contributors.