Install electrical light switch

The red wire to SW2 is connected to the hot on the bottom half of the receptacle and to the switch at the other end. In this diagram, two 3 way switches control a wall receptacle outlet that may be used to control a lamp from two entrances to a room.

This circuit is wired the same way as the 3 way lights at this link. Three-wire cable runs between the switches and the outlet. The source is at the SW1 where the hot is connected to the common terminal and the neutral spliced through to the neutral on the outlet. The red and black wires running from SW1 to the outlet are used as travelers. At the outlet, the travelers are spliced to run to SW2 using the red and white wires in that cable.

The black wire to SW2 is connected to the hot on the receptacle and to the common on SW2 at the other end.

It's common to describe household wall receptacles that are wired together using the device terminals as wired in series. But, in fact, all household receptacles are always wired in parallel, and never in series. In a series circuit, current must pass through a load at each device.

The load itself conducts current down the line to the subsequent loads in the circuit. A series circuit will drop use some voltage at each load until it dwindles to an insufficient level at some point down the line. If wall receptacle circuits operated like that, you wouldn't be able to plug an appliance in down stream from another appliance in the same circuit because the voltage wouldn't be sufficient to run it. And if the appliance in the first receptacle shorted out or failed in some other way, it would interrupt the current to the other outlets in the circuit.

Household circuits don't operate like that, you have a consistent average of volt at each receptacle, no matter how many loads you have on the circuit. By contrast, switches and circuit breakers are wired in series. Voltage passes through these devices in order to continue down the line.

If an interruption occurs in a switch, there will be no electricity beyond that point. By code there is a limit to the number of conductors allowed inside an electrical box, depending on the wire gauge you're using and the size of the box. While wires are conductors, they aren't the only ones in an electrical box. Devices like switches and receptacles are also considered conductors, and they add to the total present in the box. All metal parts that qualify as conductors must be added, to determine the total you will have in the final installation.

Find detailed explanation of how to count conductors here. How to Read These Diagrams This page contains wiring diagrams for household light switches and includes: a switch loop, single-pole switches, light dimmer, and a few choices for wiring a outlet switch combo device.

Wiring a Switch Loop When the electrical source originates at a light fixture and is controlled from a remote location, a switch loop is used. Wiring Two Switches for Two Lights Here two switches are wired in the same box to control two separate lights.

Multiple Light Wiring Diagram This diagram illustrates wiring for one switch to control 2 or more lights. Dimmer Switch Wiring Diagram A rheostat, or dimmer makes it possible to vary the current flowing to a light fixture thereby varying the intensity of the light. Wiring a Switch to a Wall Outlet Here a receptacle outlet is controlled with a single-pole switch.

Wiring Diagram for a Split Outlet This diagram illustrates the wiring for a split receptacle with the top half controlled by SW1 and the bottom half always hot. Wiring a Double Split Switched Outlet In this circuit a split receptacle is controlled by two separate switches. Email Print. Home Page. The requirement for a neutral in a switch box has only been introduced into the National Electrical Code a few years ago. Prior to that the electrician that wired your home originally would install the wiring in a manner that was suitable for him or her.

You cannot use the grounding conductor to connect the smart switch neutral wire to. This can create an unsafe condition throughout the home and may cause problems with electrical appliances. It is forbidden by article In the United States standard residential lighting circuits are volts at 60 hertz HZ.

The switch must be compatible to that. Some of the smart switches that I have seen have a voltage range from volts for residences to as high as volts, which is for commercial lighting. To replace a wall switch with a smart switch first turn the power off using the circuit breaker for that circuit. Remove the wall plate covering the existing switch by unscrewing the two screws.

Remove the switch by unscrewing the screw at the top and the screw at the bottom. Gently pull the switch away from the wall. Sometimes the wires are too short to pull the switch far.

If you see a white wire on the existing switch, that is not a neutral. As I explained above the white is supposed to be re-identified with another color, but is often neglected. Check that the power is off using a non-contact voltage detector. Remove the two wires from the screw terminals on the side or the push-in connections in the back of the existing single pole switch.

You can use a tiny screwdriver or a paper clip to remove the pushed in wires. Do not cut the wires. The wires in the switch box are all that you have to work with. Now pull out the white wires that are inside of the switch box, but do not take them apart.

Remove the wire connector on the white wires so that the bare wire is exposed. Keep the joined white wires separated from the wires off of the switch. Put one of your volt meter leads Or pigtail light bulb on the white wires and touch the other lead to one of the wires that were removed from the switch.

Then check the other wire that was removed from the switch. The switch wire that shows approximately volts with the white wires is the LINE. The other wire with no voltage is the LOAD. Ignore voltage readings that are much lower than volts. Turn the power off again.

I have noticed that some smart switch wiring diagrams from the manufacturer have the equipment grounding conductor colored yellow. Standard electrical code wiring practices in the United States require the grounding conductor to be green or a non-insulated bare wire. Other countries may have the ground wire as yellow with a green stripe, or green with a yellow stripe. In your switch box you should have one or more grounding conductors spliced together with a wire connector or wire crimp.

The ground wire from the smart switch needs to be connected to that. If the wires are crimped and there is no pigtail to connect to, you will need to remove the crimp. I do this by carefully cutting the crimp parallel to the wires using my Knipex high leverage diagonal pliers.

Try not to cut the wires. With the ground wires now separated from the crimp, twist the ends together tightly using pliers. Tightly twist the ground wire from the smart switch onto this group of ground wires. Twist an appropriately sized wire connector onto the end. In some cases the grounding path is established through the metal armor of the cable or metal conduit.

Remove all unused clamps from inside of the box. The smart switches are generally compatible with wall plates suitable for Decora switches though the colors may not be precisely the same. For three way switch wiring diagrams go to my blog post. My blog post with Four way switch wiring diagrams is very useful. For switched and half switched outlet wiring diagrams see my blog post here. Click here to see my blog post about grounding switches and outlets. Sign in.

Forgot your password? Get help. Privacy Policy. Password recovery. Wiring diagram shows how the electrical power enters the ceiling light electrical box and then a two conductor cable is installed to the switch without a neutral conductor.

Light switch wiring diagram of a ceiling light to a light switch using 3 conductor cable to the switch. The power enters the ceiling light electrical box and branches off to the single pole wall switch using a three conductor cable. Light switch wiring diagram depicting the electrical power from the circuit breaker panel entering the wall switch electrical box and then going to two ceiling lights via a two conductor cable.

The grounding conductor in the cable is not shown in order to simplify the diagram. Equipment grounding conductors usually bare copper, sometimes green are a safety system that allows electricity to return if something goes wrong. What size box do you need? To prevent overheating, the National Electric Code restricts how much junk you can jam into a box.

The capacity, in cubic inches, should be marked on each box. Here's how to calculate the box size needed:. Multiply by 2 for gauge wire or 2. Result: minimum box volume required, in cubic inches. In this article, you will find: Safety and terminology Use the force Make a breakthrough Go fishing Finish the job Dim the lights.

Basic Electrical Jargon and Safety Working with electricity is not tricky, but it can be dangerous. The following jargon and basic rules will help keep you out of trouble: Hot wires usually black, sometimes red carry incoming electricity.