There are many times when you will need to add or upgrade electrical, cable tv, telephone or other services in your home. To do so you need to understand both how circuits are designed and how your home is constructed to fish the wire through walls and make proper connections.
In other HowTos we will cover wall construction in more detail but lets take a look at the components of an average wall so we know how to run our wires.
The average wall is made of 4 basic parts.
• Plywood sheathing on the outside of the home.
• Drywall on the inside.
• 2×4 Studs that make up the height of the wall.
• A Top and Bottom Plate 2×4 that all the studs are connected to.
When building a new home you build the stud wall part first out of the 2x4s and then apply the exterior plywood. Much later in the construction you add the drywall on the inside of the house. When the wall is open during construction this allows you to run electrical, plumbing and other services easily.
Once the home is built you can still run wires relatively easily by a process called fishing.
Fishing is when you drill a half inch hole in the top or bottom plates of the wall and insert your wire into the hole. To get at the wire you cut a small opening for the outlet box and then use a coat hanger or wire fish to pull the electric wire out of the hole.
To find the location that you will place your outlet box you first find the wall studs which are 16 inches apart. Use a stud finder if you have one for best results or drill a small hole and then use a coat hanger to find the distance to the stud. Now you can cut the opening for your electrical outlet box leaving the hole open so you can get at your new wire.
If you will be going into your attic you can drill a hole in your ceiling drywall and insert a wire that you can find when you go up in your attic. If you will be drilling through the bottom plate you can drive a 3 inch screw through your carpet or between the carpet and your wall molding. Once you are in the basement you will see the screw and know that you need to drill the hole about 1-1/2 inches in towards the center of the wall to enter through the bottom plate of the wall above you.
Pull the wire through the outlet box letting it extend out about a foot and then attach the outlet box to the stud with screws. In the attic or basement where the wire exits the wall plate attach the wire with an insulated electricians staple. (don’t penetrate or crush the wire with the staple)
Now you can run your wire back to your Electrical Service Breaker Box or to another location depending on the service you are installing.
Attach the wire every 4 feet along the run back to your service with Electrical Staples making sure you do not penetrate or crush the wire with the staple. The wire should be snug but still a little lose that way you know you did not make it too tight. The idea is to hold the wire in place not make it a structural part of your home.
When you are making turns with the wire it is important to make wide round angles and do not bend the wire to make it conform to right angles.
If you are running wire in the attic then attach the wire towards the floor of the attic on the joists or trusses (or a foot or so up so visible above the insulation) and not to the roof trusses.
If you are running wire in the basement you can drill holes in your joists but it is better to attach them in the center of the joist along the run and then to the bottom of the joist when you are running perpendicular or against the direction of the joist. When running wires along the bottom of the joists you want to do so at the outside perimeter of the room when you can to reduce the possibility someone will use the wire as a place to hang things.
If you are running wires for lights in your basement then running down the center of the room is not a problem.
Lets look at the most basic type of circuit a Home Run. This type of circuit is a single wire running from your service to the appliance you want to connect to. Home run circuit are often used for kitchen ranges, heating furnaces, air conditioners, 220v dryers and other items that require a dedicated private circuit and consume a large amount of electricity. Home run circuits are also used for computer networks, telephones and cable tv / satellite systems.
Installing a Home Run Circuit
Lets say you are adding a large in the wall air conditioner for your home that requires a 20 amp circuit. Most home wiring (type 14-2) can only serve 15amps of electricity so to install a home run circuit you will need to take the following steps.
First since you will need to install a 20 amp circuit breaker in your service make sure you have an open spot for it. Making the connection at the box is the last step but you need to know you have an open slot to put it.
Now like described above you need to run the wire from the breaker box to a wall outlet that you will place near the air conditioner.
Remember to allow about 1 foot of extra wire exiting the outlet box and about two feet of extra wire at the Service box.
Strip back the plastic sheathing on the wire so that only about an inch remains inside the receptacle
Attach the wires to the back of the outlet with the bare ground going to the green screw, the black wire (positive) going to the brass colored screw and white wire (neutral) going to the silver colored screw.
Double check that your connections are clean and tight then insert the receptacle into the outlet box making sure that the ground wire does not touch the white or black connections and screw the outlet to the box.
We can now install our circuit breaker at the service box.
Turn off your main circuit breaker that feeds electricity to the rest of the service. Test the presence of electricity with the appropriate electric probe tester to make sure the box is not still live. In some instances you may need to remove your electric meter from your meter box to make sure no electricity is entering your Service Circuit Breaker Box.
In most boxes there is a separation of ground and neutral wires on separate sides of the box. strip the ends of your wires and insert them into the appropriate bus bars and clamp them down with the set screws.
Strip off and attach the black wire to the circuit breaker and insert the breaker into the box. One end goes in first and then you rock the back side into place until it clicks and makes full connection.
Once all the connections are made and triple checked you can restore power to the main circuit breaker. Now turn on the circuit breaker for your new circuit.
Do not plug in an appliance to check your work. You should use a proper tester first to make sure there are no cross connections, shorts or outs in your circuit.
Once you have tested the circuit you can place a outlet cover over your new outlet box and put the line into service.
AGAIN WARNING working on your homes electrical system can lead to very serious injury and even death. It can also void your homes insurance policy.
You should always work with a qualified technician when performing electrical work.
If you need to save money ask them if they will give you a discount if you supply materials and perform some of the work yourself. But no matter how much of the work you do yourself a final inspection by a building official or certified technician who can check your permit is always required.