House electrical wiring is a way of connecting electrical wires to related materials like switches, circuit breakers, sockets, distribution boards, light fixtures, and then linking them to a utility pole for a power supply.
A licensed electrician who understands electrical diagrams and safety standards does this.
During installations, he considers the electrical loads, operating voltage, and national electrical code requirements before choosing the suitable wire size.
Types of electrical wires used in home wiring projects
there are 6 types of cables used in electrical work, they include:
Romex or NM cable.
This is the most common type of cable used to wire a house. It contains three or more wires (one or two hot wires, a neutral and a bare copper ground wire) wrapped with a protective sheath.
NM cables are best for interior dry places to connect appliances, light fixtures, and outlets. They are colour coded to show their wire gauge.
Nonmetallic cable colours, gauge, and their uses
| NM Cable Colours | Size or Gauge | Uses |
| White sheathing | 14 gauge conductor | 15-amp circuit |
| Yellow sheath | 12 | 20-amp circuit |
| Orange sheathing | 10 gauge wires | 30-amp circuit |
| Black-sheathed cables | 6 and 8 gauge wires | 40 amp circuit |
| Gray sheathing | 6 | 55-amp circuit |
Underground feeder cables (UF)
This is the type of nonmetallic cable used in wet locations to supply current to outdoor fixtures.
Usually buried in the ground, the cable comes with a solid plastic sheathing around the insulated hot wire, neutral, and ground wire.
We can also use them for major circuit wiring.
Armored Cable (AC) also known as BX
This galvanized spiral metal was once the major material for wiring electrical circuits in the early 1900s, but after the invention of nonmetallic cables, the use was reduced to areas where extra protection on wires was necessary.
Armored cables come with 2 or 3 insulated wires that run through the Armored casing. In a two wire cable, one is always black (the hot wire) and the other one is white (neutral).
Low-voltage wires
We use it for circuits that draw less than 50 volts. They are used to wire small appliances that require small energy, such as doorbells and landscape lighting.
Low-voltage wires come in various gauges ranging from 12 to 22 and are insulated or covered in cable sheathing.
THHN/THWN Wire
THHN and THWN are the two most common types of insulated wires used for conduit wiring.
Unlike the NM cable, where two or more single conductors are bundled inside a plastic sheath, THHN and THWN wires are separated, each with its color-coded and they are protected by a plastic conduit.
- Hot wires are black, red OR orange;
- Neutrals are white or brown;
- Ground wires are green or yellow-green
THHN/THWN stands for
T: Thermoplastic;
H: stands for Heat-resistant and
HH: highly heat-resistant;
W: Rated for wet locations;
N: Nylon-coated, for added protection.
These types of wires are used in places like basements or garages and inside the house, to connect some devices like water heaters.
Phone and data wire
Phones and internet wiring require low-voltage wire type, and the most suitable one for this is category 5, (cat 5).
Telephone and data cables have about four to eight wires, while the cat 5 cable contains eight wires, wrapped together in four pairs and is suitable for phone and data transmission.
Tools and materials required to wire a house
- Wire tester: To test if the power is ON or OFF.
- Screwdriver: For loosening and tightening of screws.
- Hammer: To drive in nails, and for other purposes
- Wire stripper: Removing of wire insulators
- Power drill: To drive in screws
- Chisel: For cracking walls.
- Utility knife: To remove insulators
- Tape measure: For measurement and in making estimate and quotation
- Fish tape: To draw cables in conduit wiring
- Plier: For cutting and twisting of wires
- Marker or pencil
- Electrician gloves: For hand protection against electrical shock
- Plumb: To make sure your work is level
- Flashlights, and others. Helps when working in dark areas.
How to wire a house
To wire a house, follow these procedures
1. Develop a wiring plan or diagram
If you are new to electrical work, consult a professional for the plan. But if you can develop and read an electrical blue print, do it yourself.
The plan will map out the connections and where to install the outlets, light fixtures, circuit breaker panel, junction box, and others.
Locate and mark electrical box positions
Using a marker or pencil and your tape measure, locate and mark the spots you will install electrical boxes on the wall.
the height of the boxes from the ground should be 2 to 3 feet, while that of the light switch should be 5 feet.
Mark each spot as either a single switch, dual outlet, three-way switch, or light fixture using an electrician symbol or initials.
Crack the walls and install outlet boxes and PVC pipes
Once you are through with marking, crack the walls from the metal box spot to the ceiling.
Install the metal box and fix a PVC pipe into the knockout hole and join them with a couple join.
Do the same for all the places where you have an outlet box and light switches and draw the pipe to the place where you will install the main breaker.
Size your cables
The load which the circuit shall carry will determine the size of the cable and breaker to install.
You can use 14 gauge wires on 15 amp circuits to control light bulbs and small appliances, 12 gauge wires on 20 amp receptacles, 10 gauges on 30 amp breakers, and 8 gauges on 50 amp circuits if you need it.
Feed in your cables
Feed the cables from your outlet boxes and pull them to the main breaker using your fishing tape.
Make sure you use the right gauge wire for each outlet. Also, each 240 volt appliance should be on its own circuit.
Install the outlets, switches, and light fixtures.
Install sockets, switches, and light fittings on their various boxes. Make sure you wire the plug socket correctly
The socket comes with three screw terminals: neutral, live, and earth terminal. Connect the live or hot wire to the L terminal, neutral to the N terminal, and blue or green wire to the earth terminal.
Tighten the wire screws and cover the face plate.
Mount the main circuit breaker panel
Now that you are through with the installation of outlets, mount the electrical panel. Pull the outlet wires into the panel and connect the branch circuit breakers, earth wire and neutrals.
connect the main service wire to complete the wiring.
Electrical wire colour code and where to use them.
- Black wires: Black or hot wires carry currents from the electrical service panel to outlets and light bulbs.
- Red wires: these serve as secondary hot wires and are mostly used when installing ceiling fans where there is a light switch.
- White and gray wires: These are neutral wires, but can sometimes carry currents when there is an unbalanced current load. Neutral wires carry the current back to the service panel.
- Green wires: These are earth wires that connect the earth terminals of all the outlets to the ground, so that whenever there is a short circuit or power surge, it flows through it to the ground.
- White wires wrapped in black or red tape: These are also hot wires. The tape is to tell you that the white wire, which used to be neutral, is doing the work of hot wires in the installation.
- Bare copper wire: Grounding wires
- Blue and yellow wires: These wires are sometimes used as hot wires in conduit wiring even though they are not found in non-metallic cables.
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