Skip to Content

How To Wire A Single Light Switch

How To Wire A Single Light Switch

This article will help you understand the different methods on how to wire a single light switch. Read on to see which method applies to your application. Hopefully we can clarify it for you.

As per 2018 current electrical code. You are required to have power running through the device box when planning on how to wire a single light switch. Needed is a neutral or white wire present inside the switch box. This is common in all lights switches as many new devices need this neutral connection to work.

There are a few different ways to wire a light switch.

10 Methods On How To Wire A Single Light Switch

  1. Wiring a single pole switch
  2. How to wire a double pole switch
  3. 3 way switches
  4. Wire a 4 way switch
  5. Terminating several switches
  6. Does it matter which wire goes on the light switch
  7. How do I wire a single light switch with 3 wires
  8. What if the power wire runs to the light first
  9. What amperage does the switch need to be
  10. Why is there a ground wire on the light switch

1.Wiring A Single Light Switch Single Pole

Wiring a single pole switch is relatively easy. Inside of the wall box you will see two black wires coming out to the switch.

Those two black wires break the actual circuit going to the light. You also see two white wires they get wire nutted.

If you follow the diagram below you can see quite clearly that the power feed comes from the power source. In this case it would be from the power panel.

This would be a 120 V power feed. The power feed then would terminate inside of the switch box. The load side of the switch would then terminate at the light box or in this case spotlights.

This is the most simple form when it comes to how about to wire a single pole switch.

You will notice as mentioned above the white or neutral wire carries right through to the light fixtures. This type of wiring is usually done with NMD 90 14/2 wire.

2.How To Wire Single Light Switch Double Pole Application

When wiring a double pole switch the process is slightly different. A double pole switch actually breaks both sides of the circuit.

This method is commonly used for shutting off 240 V loads. Since 240 V loads do not have a neutral wire it is considered by code to be safe to break both sides of the circuit.

An example of what this would be used for would be to turn off and on a hot water tank. It could also be used for turning on or off a safety switch for any 240 volt loads like a water pump.

On the back of the switch it will have an actual line side and a load side.

3.Wiring 3 Way Switches

The diagram below shows common uses and common wiring of a basic three-way switch. Three way switches are used for areas like hallways or top and bottom of staircases.

They help switch a light or several lights from two locations. You may often hear them referred to as a two way however the proper terminology is a three way switch.

In this case the power is coming from the panel through the first switch box to the second switch box and then to the light fixture.

Notice that The wire coming from the panel is a piece of 14/2 nmd. The wire between the two 3 ways is actually a piece of 14/3. This extra wire between the two 3 ways is for the travelers to work.

The commons or terminals on the three ways receive power from the panel.

The last common on the second three-way goes back up to turn the light off and on. The travelers go between the two 3 ways.

This creates a flip-flop action between the 3 ways which actually transfers power from one location to another to then turn off or on the light fixture.

You can find more on 3 way switches here.

how to wire a single light switch

4.How To Wire A 4 Way Switch

Wiring a 4 way switch is more complicated. A 4 way switch is installed between two 3 way switches. This is so you can switch the light from 3 different locations.

These installations are common in larger homes with big rooms that have a few entrances.

To simplify a 4 way it simply changes the direction of the power on the travelers between the two 3 ways.

It would be installed as a center point in the 14/3 wire running from 3 way to 3 way.

The red and black travelers of the 3 wire would be broken by the 4 way switch.

5.Wiring Several Switches

Since we talked about 4 ways, it is easy to understand that you can have as many as you like in a light circuit.

The 4 way goes between the two 3 ways. You can have as many 4 ways as you like between them. This allows the light to be switches from several positions.

There are also smart switches on the market today that simply wire into any power circuit to control lights.

That simplifies the wiring process however a bit more expensive up front.

You can find out more on this type of switching system here.

6.Does It Matter Which Wire Goes On The Light Switch?

Most common single pole light switches do not care which black hot wire goes on them. They will still break the circuit and do their job.

With that being said, dimers, timers or anything electronic does matter.

It’s important to get the line and load correct on an electronic device. it will simply not work unless you do.

Unfortunately the only way to really tell the line load of a switch is to test for power with a voltmeter.

how to wire a single light switch

7.How Do I Wire A Single Light Switch With 3 Wires

When you run into a switch with 3 wires it is usually because power was run through the switch to give constant power to an outlet.

We do this when we have power at the light and want to drop a plug below the wall switch box. The piece of 14/2 wire feed from the panel runs to the light box or octagon first.

Then we drop a piece of 14/3 down to the switch box. Another piece of 14/2 drops from the switch box to the plug.

The white wire actually goes right through the switch box down to the plug. The black wire also goes through however has a tail to power the bottom of the switch.

The red wire or third wire goes back up to the light to switch it on and off.

8.What If The Power Runs To The Light First?

The diagram below show the power coming into the light fixture first. It then drops to the switch to make or break the circuit.

As per new code we are now required to drop a neutral wire to the light switch.

You will notice that the example is actually a set of three way switches. The common coming back up from the switches returns to the light box to turn it off and on.

how to wire a single light switch

9.What Amperage Does The Switch Need To Be ?

Generally a light switch is 15 amp. Some switches have a 20 or 30 amp rating of them but most switches in residential are just 15 amp.

When you get into larger switching applications it usually consists of relays doing the switching.

This is usually done in larger commercial applications like stores, arenas etc.

One switch can control several relays to turn off and on several banks of lights. The relay itself can control multiple circuits at once.

10.Why Is There A Ground Wire On The Switch?

The ground wire is on the switch to ensure the switch has a good ground. Many electrical boxes can contain plastic not making a good ground.

Even worse sometimes when the wall material is replaced like the drywall or plaster.

The electrical box sets too far back in the wall to make proper contact with the device. Having a ground right on the switch ensures a ground.

In a case like this we use what is called a plaster ring or a box extender.

The device screws onto the front of the electrical box which extends its length.

This allows for the plug or switch to make direct contact to metal supplying a good ground.

Careful though some switches can fool you like a 3 way. We have seen ground wires hooked on the common of a 3 way causing a short circuit.

Look for the green terminal screw. This indicates ground.

As a 2018 current electrical code requirement we have to extent the ground wire or bare copper wire from the end of the box long enough to attach to the switch.

how to wire a single light switch

Does it matter which wire goes where on a switch?

The wire that is connected to the hot side of a light switch is always going to be the one that’s used in order to complete and break the circuit.

Now, there are two different ways that you can wire a light switch: One way will have the white wire on the right and the black wire on the left. The other will have the white wire on the left and black wire on the right.

There’s no “correct” way to do it, only two different ways. It really all comes down to personal preference.

It’s best to consult your local electrician before making any final decisions so they can help you decide which is best for your home!

What does L1 and L2 mean on a light switch?

In an electrical switch box, you’ll find two sets of wires called “L1” and “L2.” The reason the two sets exist is because not all light fixtures require a neutral connection to function.

When wiring a single light switch, you’ll need a neutral wire present. This is needed for newer types of electronic devices which require a neutral connection in order to operate. To make sense of what L1 and L2 are, let’s look at a circuit diagram:

The L1 wire carries current from the breaker panel to the load – in this case, the light fixture or electric outlet. The L2 wire returns power from the load back up to the breaker panel. In the diagram, it’s noted that there’s no return path for current from the light fixture back to the breaker panel. This means that if you have multiple lights on one circuit, only one will be able to function at a time.

How do we solve this? By adding an additional set of wires – called “neutral” – so that both lights can be occupied by a live return path.

What happens if I wire a light switch wrong?

If you’re not sure how to wire a light switch correctly, it’s best to call an electrician.

It may seem like common sense that wiring a light switch incorrectly can damage or even start a fire. But if you’re new to the world of wiring, it can be hard to know for sure.

Let’s say you run electricity under your sink and need some way to turn the water off. You might think it would be best to wire your tap on/off lever with the power coming from your light switch. This way, when you flip the light switch off, the water will also turn off.

But this is incorrect! When wiring a light switch incorrectly like this, you risk overloading your electrical system and potentially starting a fire. So don’t do this! It’s always best to call an electrician if you’re not sure how to wire something correctly.

Does my light switch have a neutral wire?

We’ve all had this question before, and it’s easy to answer: did you see a white wire in the switch box? If so, then your light switch has a neutral wire.

But if you’re not sure, there are some helpful tips to help you find out.

-If you don’t see that white wire in the switch box, then it doesn’t have one. You’ll need to add one on your own.

-If the wires inside the switch box are bare, they’re probably colored black and red; this is called a hotwire connection. These wires will make up the live and switched connections and will not include a neutral wire.

-If you see more than three wires inside the box, or two white and one black, then it does have a neutral wire.

Which wire is hot on light switch?

What does the black wire on my light switch do?

When wiring a new single light switch (where you only need one switch), there is no need for any additional wires. Just make sure to label which side of the box is hot and which side is neutral, if applicable.

The traditional “hot” conductor will be connected to the screw terminal marked “power” or “line.” The “neutral” (or white) conductor will be connected with the screw terminal marked “neutral.”

Where does neutral go on a light switch?

A common question we get about wiring a light switch is, “Where does the neutral go?” The answer to this question depends on where the breaker box and main panel are located.

If the breaker box and main panel are located in the same room as the light switch, connect the white wire from the light switch to a neutral bar wired into the breaker box or main panel. This should be done whether or not anything is plugged into that outlet yet.

If your breaker box and main panel are located in different rooms, connect both of those wires to a neutral bar wired into either one of them. If you’re connecting one wire to each location—either because you have an odd number of wires or because you don’t want to use up two outlets—connect them to ground bars instead.

Make sure whichever connection you make has enough slack for future connections and remodels!