Wire How To: Single Switch and Light

This is a typical diagram of how to wire a light switch.  There may or may not be a power out line that feeds something else in the circuit, or there may be more than one power out line, depending on what was handy for the electrician at the time.

CAUTION:
DO NOT EVER WORK ON LIVE ELECTRICITY!  ALWAYS TURN OFF THE CIRCUIT BREAKER BEFORE TOUCHING THE WIRES!  EVEN IF YOU TURN OFF THE POWER, TREAT IT LIKE IT IS STILL HOT!  ELECTRICITY CAN KILL YOU!

Ground Wire:
The orange line represents the ground wire.  This is typically the bare wire or sometimes it’s green.  Not all switches have a ground wire connection, but it is a good idea to have it.  Some older homes don’t have a ground wire in the wiring, so it may not apply.  It’s just an extra safety precaution in case the switch breaks on the inside and somehow connects the hot wire to the body of the switch (wouldn’t that be a rude awakening?).  If the ground wire is connected and that happens, the circuit breaker will see a short circuit and kick off.

Neutral Wire:
The neutral wire is the circuit return path and is normally colored white.  All the white wires should be tied together to complete the circuit, and as you can see, there is no connection on the switch for it.  DO NOT connect them to the switch unless you want to see fireworks (or at least a popped breaker)!

Hot Wire:
The hot wire is typically the black wire.  Tie all your hot wires together to feed the other devices in the circuit, except the one going to the light (called the switch leg).  If there are no power out wires in the box, only the one hot wire coming in, you can just connect it directly to the switch.  If there are other power out wires, you will have to tie them all together and cut off a short piece of black wire and connect it in with the others to supply power to the switch.

It’s always a good idea to twist the wires together with your pliers before screwing on the wire nut to ensure a good, solid connection.  It will help to prevent intermittent problems.

Wire How To: Single Switch and Light (alternate)

This wiring diagram is for when your power feed is in the light box instead of the switch box.  You’ll notice the main difference being that you use the white wire in the cable going to the switch box as the switch leg and the black wire as the power feed.

Some electricians will tie the white wire in with the power feed and use the black one as the switch leg, but either way, the switch doesn’t care which is which.

Again, I cannot stress enough to be very careful with your connections here.  If you accidentally tie the white wire from the switch into the other white wires in this configuration, there will be fireworks!

Here’s a wiring diagram of a light circuit with three lights hooked up to one switch and an outlet receptacle in the same circuit.  You can hook up as many lights or receptacles together in this way as the circuit will handle.

Wire How To: Three Lights on a Single Switch and an Outlet Receptacle

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Wiring Diagram: 3-Way Switch

This is a typical diagram of how to connect 2 switches to the same light. It’s especially handy for stairs, hallways, and big rooms.

You will notice that the power feed goes into one switch box, while the switch leg (light wire) goes into the other.  There is also a “traveler” line that connects the two together.

Traveler:
The traveler is a 3 wire Romex cable with a ground.  In other words, there are 3 insulated wires and an uninsulated ground wire.
The ground wire is for added safety and all grounds should be tied together to maintain the safety path.
The white wire is the neutral wire which is the circuit return path for the light.  It also goes to ground, and all white wires should be tied together to maintain the circuit path.
The red and black wires are the travelers that hook the two switches together.  These are attached to the 2 top terminals (or bottom – depending on how you’re holding it).  It doesn’t really matter which one goes where on those 2 terminals.

Wiring Diagram: 3-Way Switch (alternate)

This is an alternate way to wire 2 switches to the same light.  Sometimes it’s more convenient to put both the power feed and the switch leg in the same switch box.