This is an important point to remember in home electrical wiring. If you’re doing your own electrical work, you are an electrical contractor because you will do everything according to a national standard. You will need to follow code for cable, circuit breakers, and wiring methods. By all means, practice safety when working with electricity. Lock out all breakers and communicate with members of the house what you are doing.
All licensed electricians know the rules really well, but they still have to be approved by inspectors just like everybody.
If someone comes a few years later and works on your electrical system, that person will assume that when he or she grabs a plain, white neutral wire, his or her hair won’t get curled.
That’s because everybody follows code, or at least, is supposed to follow code. Personally, I keep my voltmeter handy when testing any electric supply. Black wires are hot. They are wired only to hot terminal screws or other black wires.
Red wires are hot and are usually either a traveler wire (for 3-way switches), or an extra 120-volt line to double voltage for a 240-volt appliance. Red wires are also only wired to hot terminal screws and other red and black wires.
White wires are neutral and are only wired to the neutral bus at the service panel, the neutral terminal screw on receptacles, or other white wires. Bare, copper wires and green wires are ground wires and they attach to other ground wires or can be terminated in metal boxes.
The basic cable for home electrical wiring is Romex 12/2. This is just a non-metallic, sheathed cable of different sizes and number of wires inside. The size of wire is the gauge. That’s the first number. The second number states the number of wires, which are 2. Actually, there are 3 wires if you count the ground wire, but nobody does. Almost every electrical contractor refers to the electric cable as “Romex”.
Also, a lot of 12/3 Romex will be used because it has an extra wire in it and it is required by most codes to be used where there are 3-way switches that need that extra wire called a traveler.
There is one exception to the color code rule that needs to be mentioned. In certain situations, such as in 3-way switches and dual control, dual light switches, even 12/3 cable falls one wire short of enough hot wires.
In this case, it is legal to use a white wire as a hot wire only if the wire is painted or wrapped with black tape on both ends. This is very common. Here’s two common types of electrical wiring cable.
Now that we have learned a few things about how electrical wiring in the home works, it’s a good time to get into the thick of the installation methods and to also show many kinds of wiring diagrams.
The easiest way to get started on the actual wire installation is to nail all the electrical boxes in place. These are the boxes for all outlet receptacles, light switches, ceiling light boxes, and junction boxes which include phone and TV cable outlets as well.
After all the boxes are in place, the wiring is a simple matter of running the cable from box to box. Remember, cable is quite inexpensive, so try to make the cable runs look neat and organized even if you have to use a lot of extra cable. Use staples to fasten loose or hanging cable.
You will use standard 12/2 and 12/3 Romex for all the 120-volt circuit runs. Some contractors still use 14/2 Romex for lighting. You will need to use 12/3 Romex for any 3-way light switches. A 3-way light switch is a light that can be turned on or off from more than one location. All 3-way switches need to be connected by a traveler wire that can only be found in 12/3 cable.
The circuits using more electricity will require different types of cable. These are special circuits that have strict codes to follow. These are dedicated circuits that many homeowners hire an electrical contractor to install, but they are no big deal.
You will need to get all local code information about these home-electrical-wiring circuits because certain areas have different regulations. For now, we will follow the National Electrical Code regulations. Remember that local codes always take precedence over the national codes.
The electrical inspector and an electric supply store will be a wealth of knowledge in that area. Most inspectors have free material to give to ensure that the guidelines are followed.
The electric water heater will be a dedicated circuit. A box won’t be necessary because the cable will run directly from the service panel breaker to the connections inside of the water heater.
You will probably also use number 10 cable with a 240-volt, double-pole, 30-Amp breaker for the water heater. Number 10 cable is thicker than number 12 cable and is able to handle higher amperage without getting hot.
Another circuit that requires special wiring is a clothes dryer. Like the water heater, it uses a dedicated line with a 30-amp, 240-volt, double pole breaker with 10/3Romex.
One thing to keep in mind here is that modern clothes dryers and ranges now use a four-wire plug. This is a simple matter of connecting the copper ground wire to the plug as well as the other three wires.
Normally, the copper ground is attached to the dryer chassis. You can also get a special adapter plug that converts a three-wire plug to a four-wire plug. These adapters are available at all appliance and electric supply stores. Many local home-electrical-wiring codes now require the extra wire because of the new plugs on all new appliances.
The one circuit in all the home electrical wiring that takes the most electricity is the oven/range. These vary quite a bit in the amount of wattages used, but as a standard, the oven/range has a dedicated circuit that uses a 50-amp, 240-volt breaker. A smart electrical contractor will place the breaker box within 20 or 30 feet of the oven to reduce voltage drop.
The cable is usually two heavy six-gauge wires for the hot lines, and a six or eight-gauge wire for the neutral. It is called range cable. This cable also comes with a ground wire for four-wire plugs.
There are other 240-volt lines depending on the heating and air conditioning structures. Most heating circuits will require at least a 30-amp, 240-volt breaker. The size of cable is typically 10-gauge, but this depends greatly on the type of heating system and the manufacturers requirements. Air conditioning systems are the same.
These heavy current lines tie into the breaker box with only the hot lines attached to the breaker, the neutral and ground wires will attach to the neutral bus bar.
The breakers just pop into place as they attach to the hot bus bars. You will need to label each breaker so you don’t forget which circuit it is.