How Do Electrical Wires Work?
Electrical wires provide current with a path of low resistance. They allow electrons to flow from a power source to an electrical fixture, device, or appliance, enabling it to function. Knowing how electrical wiring works is important for the safety, reliability, and efficiency of electrical components and connections.
At Express Electrical Services, we’re experienced in ensuring all the wires in your home are properly connected, meet the latest building codes, and are in good condition. Whenever you need help with electrical wiring, we’ll be there to address any issues or concerns.
What Are Electrical Wires?
An electrical wire conducts electricity. Contained inside a jacket, it may be bare or insulated. The common color-coded polyvinyl chloride (PVC) coatings insulate wires to improve efficiency and protect against shocks. Most electrical wires use copper as the primary conductor, which is highly conductive and inexpensive compared to silver and other conductive metals.
The types of wires used in home electrical systems include single-stranded solid wire. It is resistant to corrosion and environmental stress. Stranded wire consists of several smaller conductors wrapped around one another to improve flexibility and metal fatigue resistance. Perfused wires are much thinner and more flexible, while braided wires are smaller strands that often serve as electromagnetic shields in cables.
A cable differs from a wire in that it serves as a housing for two or more wires.
How Do Electrical Wires Carry Electricity?
An electric charge (current) moves through a wire in the form of electrons. These are part of the copper atom, which also contains a neutron and proton that don’t move. For a wire to work correctly, the electrons must move through these atoms at roughly 0.0004 miles per hour. That doesn’t sound fast, but it’s enough to allow, for example, a light to turn on the moment you flick a switch.
The electrons fill the wire conductor, when more are added, those at the end must leave. The light or connected device will remain powered as long as the wire is connected. But the process is often misunderstood. Electricity does not flow through electrical wires; electrons already exist in metallic wires and can’t be created or consumed.
Instead, an electric field oscillates, exerting a force on the electrons that causes them to move back and forth very quickly. Energy transfer occurs at the subatomic level within a conductor, so electricity does not flow as it can around a wire or through the air. However, high-voltage transmission wires, plastic wire insulation, and light bulbs leverage electromagnetic fields at this level.
Components of Electrical Wires
All electrical wires consist of these key components:
- Conductor: The conductor transmits the electrical current. It can be solid or flexible, which is defined by a minimum number of wires or their maximum diameter contained within the conductor. In homes, conductors are usually copper, but aluminum is often used for power transmission cables.
- Insulation: An insulating material, usually a plastic, polymer, or elastomer, surrounds the wire to provide resistance to high temperatures. The higher the temperature the material can tolerate, the more current it’ll allow the conductor to carry. Wire insulation also helps protect against electric shocks.
- Sheath or Jacket: The outer sheath of a cable is typically a polymeric or thermoplastic material that protects the cable and wire from moisture, mechanical forces, and other external elements. The outer sheath or jacket material can be chosen based on the required protection level, the type of insulator used, and the work environment the product is intended for.
Cables and electrical wires can also feature steel or aluminum strips, wires, or braids under the outer jacket for mechanical protection. Metal screens can prevent signal interference. Wire manufacturers may also use a filler that occupies empty spaces of insulated conductors, or place a seat over the filling to prevent contact between the insulation and metal.
Types of Electrical Wires
Different types of electrical wires may be used depending on the application. The most common ones are:
- Non-Metallic (NM) or Romex Wires: An NM wire is most often used in homes. Designed for use indoors (in dry locations), it has two or more wires (a hot wire, neutral wire, and ground wire) wrapped in a plastic sheath. Usually, NM cables look flat and tubular and run within walls and ceilings.
- Armored Cables (AC): These contain metal-clad armor that resists corrosion due to moisture exposure. It also protects cables from mechanical or environmental damage. Resistant to chemicals, armored cables can be used in industrial settings, underground, or underwater.
- Underground Feeder (UF) Cables: A type of NM cable, UF cables can be buried directly underground and tolerate wet conditions. They are suited for lampposts and other outdoor fixtures. The sheathing of a UF cable is solid plastic, which is more durable and usually gray.
- Conduit Wires: These single conductors are protected by tubular metal or plastic conduits with thermoplastic, heat-resistant properties. A nylon coating adds protection, while some conduit wires are rated for wet locations. Conduit wires are often used in basements, garages, and for short-run connections to water heaters or garbage disposals.
Electrical Wire Color Codes
The National Electrical Code has established a standardized color-coding system for electrical wires. Wire color coding has been practiced since 1928. The wire colors used indicate to electricians how power moves through a circuit. For the average user, color helps to alert them of danger. For example, red indicates a wire is hot or live, meaning there’s a high risk of shock or electrocution if someone misuses it. Black is also used to indicate hot/live wires.
White typically indicates the wire is neutral. It carries the current back to the panel, thereby completing the circuit. Ground/earth wires are usually green or bare. They allow current to return to a breaker if there’s a ground fault, allowing the system to cut off electricity.
Color also helps remember a wire’s purpose in a network. It can help identify wires to reduce downtime and costs (by preventing the wrong wire from being cut). In addition, it ensures circuits are connected properly, avoiding overheating, fires, and costly property damage.
Safety Considerations
Regardless of the type, quality, and condition of electrical wires, one must always follow safety precautions when working around them. To avoid injury or property damage:
- Shut the Power: Always turn off the power at the main breaker before handling, disconnecting, or repairing wires.
- Wear Protective Gear: That includes fire-resistant rubber gloves, insulating sleeves, and safety goggles. Do not wear any metal when handling wires.
- Avoid Working Near Water: If the area is damp, dry it off before working with any wires. If necessary, cover the damp area with a wooden board or other non-conductive material.
- Look for Damage: If a wire, its insulation, or a plug or outlet is damaged, call a professional immediately to replace it.
- Hire a Professional: If the task is more complex, request help from a licensed electrician who can safely repair or replace faulty wiring.
Contact Express Electrical Services
Electrical wires conduct electricity throughout your home. They’re found everywhere and power every connected light, electronic device, and appliance. At Express Electrical Services, our certified technicians are familiar with all common wire types, the colors used, and how to safely work with and properly install and repair them. If you have old or faulty wiring in your home, use our contact form or call (888) 350-7869 to request service.
Robert Hogward says: