Electrical wires are the metal conductors that deliver electricity to and from your appliances, lights and switches. Without them we would not have lighting, televisions, refrigerators or even the electric grid that carries electricity hundreds of kilometers. Wires are made from various metals but copper is the common material used for electrical circuits in homes and commercial buildings because it has high conductivity at a low cost. Electrical wiring comes in many different gauges and colors and can be solid or stranded. The size of a wire or cable determines its current-carrying capacity, which is determined by how much power it can safely carry. Tables in electrical safety codes list the maximum allowable current for a particular run based on wire size, voltage potential, insulation type and thickness, and environment (wet or dry, hot or cold).
Most electrical wires are composed of multiple solid or stranded wires bundled together into a single jacket that protects the metal conductors. The jackets can be a variety of materials but thermoplastic high heat and water resistant nylon-coated or thermoplastic high temperature resistance nylon-coated (THWN or THHN) are the most common. A wire can also be perforated or braided. Perforated wires have holes in them to provide more flexibility and are commonly used for welding electrodes, connecting machine parts, computer mice and musical instruments. Braided wires have several small wire strands that are twisted together and provide more flexibility than solid wires.
When you plug a light or appliance into an outlet box the black wire will connect to a brass terminal and the white wire will attach to a silver terminal. The green (or sometimes bare) wire is the grounding wire, which will take the electricity back to your breaker panel and then to a rod that’s buried in the ground. This keeps you from getting zapped when something goes wrong with your home’s electrical system.
Before changing any of your household electrical wiring, read a good how-to book and study an electrical diagram. This way you will be able to follow the rules of safe and efficient wiring and ensure that your work complies with local and national electrical code requirements. Incorrectly installing or altering the wiring in a house can create a fire hazard and may prevent you from selling your home.
The wires in a home’s electrical circuit are all connected to the same breaker box and the power travels along those lines to outlets, lights, switches and other appliances. In residential wiring the most common is 12 or 14 gauge wires, which are rated for up to 55 amps. These are adequate for most lamps, doorbells, intercoms and thermostats. Larger appliances like stoves, water heaters and dryers require larger gauges of wire to handle the higher amperage loads. For long runs of wire, especially those that are enclosed in conduits, thicker, heavier wall studs or other building materials, you will need to use a bigger gauge of wire.