See Article The neutral is needed for the use of electronic dimmers , timers, and WiFi smart home devices that can be installed instead of an ordinary light switch.
This is why the above wiring diagram is not used much anymore. All of article pertains to the installation of switches. It is very important to follow the electrical code and other building codes for the safety and protection of your home and family. The photo above depicts the wiring diagram of a ceiling light and light switch with the power from the circuit breaker panel entering the ceiling electrical box.
From the ceiling a three conductor cable with a grounding conductor is used to send power to a light switch. The grounding conductor is not shown in order to simplify the wiring diagram.
It is easy to supply power to more than one light fixture as the wiring diagram above shows. You just install a cable or conduit from a ceiling box to the next ceiling box. The main thing to watch out for is having too many wires in one electrical box. There are code mandated limitations as to the number of wires that can be in an electrical box as well as physical constraints.
See article Generally speaking each individual 14 wire requires two cubic inches of space inside of an electrical box. A 12 wire requires 2. A switch counts as two wires. In addition deductions must be made for connectors, clamps, and studs inside of the electrical box. If you wanted to control the two lights separately from two different switches in the same box, a three conductor cable with ground would need to be installed to the first light instead of a two conductor cable.
At the first light you connect the black and the white wires. The red wire would continue to the next light along with a white wire using a two conductor cable. Of course you could also install two separate two conductor cables to each light from the switches. The above light switch wiring diagram depicts the power from the circuit breaker panel going to an electrical receptacle outlet and then continues to the next outlet and then to a single pole wall switch and then to another outlet.
Multiple receptacle outlets can be connected with lighting outlets as depicted in the above light switch wiring diagram. Duplex receptacle outlets are made for feed through of the power from one receptacle to the next. The above wiring circuit was made using only a two conductor cable with ground. The grounding conductor is not shown in order to simplify the diagram.
If a ceiling fan is going to be mounted instead of a light fixture, a ceiling fan rated electrical box would need to be installed. In addition I would install a three conductor cable with ground from the switch to the ceiling box. This would allow for the option of having two switches, one for the fan, and one for the light kit on the fan.
You can read my post about installing an old work ceiling fan box. Typically the grounding conductors would be joined together in each switch and receptacle box and a pigtail would be connected as well to supply the ground connection on the green screw of each duplex receptacle and single pole switch.
Sheet metal, Tek screws , and wood screws are not permitted for ground connections. The diagram above shows a two conductor cable from the circuit breaker panel going to a wall switch. From the switch a three conductor cable continues to a ceiling light. From the ceiling electrical box a receptacle outlet is fed power using a two conductor cable with ground.
The grounding conductor is not shown in order to keep the diagram simple. When I rough-in the wiring for ceiling lights I usually install the power from the circuit breaker panel to the wall switch and only install one cable to the ceiling light electrical box or ceiling fan box. I tend to avoid feeding other things from the ceiling box so that the box can be moved easier if the homeowner decides to move the light location before construction is finished or many years after the construction work is done.
Light switch wiring diagram above shows electrical power entering the ceiling light electrical box and then continues to a wall switch using a 3 conductor cable. From the wall switch a 2 conductor cable is used to provide power to two electrical receptacle outlets. Having the neutral conductor in the switch box makes it handy to send power to other things such as receptacles as shown in the above diagram.
It could also be used to supply power to another switch that controls lights in another part of the house. A three conductor cable must be used from the light to the switch.
Although it is permitted to wire lights and receptacles on the same circuit I usually avoid doing that for the sake of the people living in the home. If by chance someone plugs an electric heater, or something else into a receptacle outlet and it overloads the circuit, the circuit breaker will trip off.
With lights and receptacles connected together in this scenario the room will have no lights until the problem is resolved. If the lights are wired separately from the receptacles, they will remain on while the problem is fixed. Electronic smart switches get wired a little differently than standard wall switches.
The smart switches also require a neutral conductor to operate. If there is no neutral wire in the switch box, such as in the diagram at the top of this page, you likely cannot use a smart switch. Though there may be a few types of smart switches available that are designed to operate without a neutral connection , the type of functions that they offer may be limited.
Research before purchasing any smart switch or lighting dimmer. 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 above diagram, the power from the electricity source is coming through a two-wire cable to the first switch.
Three-wire cables are used between the two switches. As we power this circuit, electricity will flow through the hot wire over to the second switch. As it goes through the red traveler, it will stop at switch number one. When we flip the second switch, the electricity can now go through to the light fitting and make it back through the neutral or white wire.
In order to turn the light back on, you need to flip the second switch again and the circuit will be complete. Feel free to download a PDF file of the diagram above. In the step-by-step process below, we will be connecting the wires to the power source and the light fitting attached to the same switch:. We are including PDF files for printout and reference.
To wire the circuit in this way you will require the following cables:. In this circuit, electricity goes through the hot wire to the first switch and then, to the second switch through the traveler wire. The power goes back into the neutral white wire until the light comes on.
This situation is somewhat close to the first circuit where the power is on the switch. A more detailed diagram is included in this PDF file. The step-by-step process of connecting the wires with the power source and light fitting between the light switches can be seen below:. Here is a more detailed PDF file. To wire this circuit, you will need the following cables:. In this case, electricity flows through the ceiling box from the first switch to the second switch. But when you push the button to OFF the light, it entirely breaks the circuit, and the passing of electricity is interrupted.
What happens is there is always a space between the hot wire and the switch. In this section, we will talk about how to wire a light switch. Typically, we purchase a switch from the market but for some unique situations, when you have to make it by your hand, then follow these steps. In the first step, the power comes to the switch and then travels to the light. For this configuration, you will have to work with the three wires mentioned above.
Now you have to configure the switch in such a way that power comes from the light. You have to work with the white, black, and one bare wire coming from the box you configured above. Following are some practical illustrations of the light switch wiring to make our minds and concepts more precise about what we have seen above.
This is the wiring of the single pole switch, in this case, the power source is with the switch, plus two wires are coming from the switch to the light. We can see the two brass terminals both the black hot wires are connected with the two terminals of the switch. The neutral white that is the white wire is coming from the source and is connected with the white wire and is going to the light. In the light, both white and black wires are connected with the terminal.
Here the two switches are in the same box. Two wires coming from each switch are connecting to the light. The white wire is connected with the one terminal of the bulb, and the black wire is connected with the second terminal. Here in this illustration, the case is unique as we are wiring multiple lights with the same switch.
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