Home electrical wiring is the electrical installation of cabling and associated devices such as switches, distribution boards/electric panels/breaker panels, outlets/sockets, and light fittings in a structure. Wiring is subject to safety regulations for design and installation, which affect the types and sizes of the cables you can use.
Here is everything you need to know about basic wiring terminology and identifying the most common types of wire and cable.
Understanding Home Electrical Wiring
Electricity enters your home through a service head from a series of outdoor power lines or an underground connection. A typical service head consists of two 120-volt wires and one neutral wire that supply power to lights and appliances in your home.
The 120-volt circuits use one phase of the electrical service to power standard home appliances. Larger appliances like water heaters and clothes dryers require a 240-volt circuit, which is created using both 120-volt wires and the neutral wire.
The electrical service panel is the central distribution point for delivering electricity to switches, outlets, and appliances throughout your house. The service panel is equipped with breakers or fuses that shut off power to the circuits if an electrical system failure occurs.
Common Terms to Know
- Volts: Electromotive force or potential difference is expressed in volts (V).
- Watt: A watt is a unit of power. One watt is defined as the energy consumption rate of one joule per second. It’s also defined as the current flow of one ampere with a voltage of one volt.
- kW: A kilowatt is 1000 watts.
- kWH: A kilowatt-hour is a unit of energy equal to 3600 kilojoules. One kWH equals one hour of electricity usage at a rate of 1 kW. A 2 kWH appliance would consume 2 kWH in one hour or 1 kWH in half an hour.
- MCB: A miniature circuit breaker automatically switches off an electrical circuit during abnormal conditions or overload of the network. Today, MCBs are used in low-voltage electrical networks instead of fuses.
Electrical Cable Types: The Basics
Electrical Wire vs. Electrical Cable
Electrical cables assemble two or more wires in a single jacket. Wires are the individual insulated or bare conductors inside the jacket.
Household Wire Gauge
Wires come in different sizes to work with the amperage of the circuit in which they’re used. The larger the number, the smaller the wire.
The most common gauge sizes for residential work are 14-gauge and 12-gauge. Larger appliances like electric stoves, electric water heaters, electric dryers, and central air units will often use 10, 8, or 6-gauge wire.
Types of Electrical Wires
- Black Wires
Black, red, and white wires with black or red tape will always indicate a hot wire. “Hot” means the wire carries a live current from your electric panel to the destination. Using any colors other than these for hot wires is strongly discouraged. Black or red wires always carry power from the service panel (breaker box) to your home’s devices.
- Red Wires
Red wires are usually used as secondary hot wires. Red wires should be clearly marked to avoid the dangers of electrocution. Red wires are commonly used when installing ceiling fans where the light switch may be.
- White & Gray Wires
White or gray wires indicate neutral-charged wires. Neutral wires may still carry power and pose a risk of electrocution if not handled properly. White and gray wires carry power back to the service panel.
- White Wires
White wires with black or red tape are hot wires.
- Green Wires
Green insulated wires are often used for grounding. Ground screws on electrical devices are also often painted green. Green wires should not be used for any purpose other than grounding.
- Bare Copper
Ground wires can also be bare copper.
- Blue & Yellow Wires
Blue and yellow wires are sometimes used as hot wires. Blue wires are commonly used for travelers in three-way and four-way switch applications.
What Type of Wire Is Used for Residential Wiring?
Most modern homes use nonmetallic (NM) cable that consists of two more wires wrapped inside the colored sheathing mentioned above. The package of wires usually contains one or more hot wires plus a neutral wire and a ground wire.
DIY Home Wiring & Switching Tips
If you’ve done handyman work before and have the confidence to tackle a DIY wiring job, here are some tips:
- Have the proper tools, including a multimeter and a combination sheath/wire stripper
- Make sure you know which colored wire goes and its purpose to avoid electrical shock and safely wire your home
- Have more wire than you need—make sure it stretches at least three inches outside of the electrical box
- Patch drywall with large electrical plates
- Use quality switches and outlets
- Check the voltage before you touch wires and circuits
Many states and local jurisdictions permit homeowners to perform electrical work, but some do not. Before doing any DIY electrical work, check with your local or state building department to see what licenses or permits are required. The National Electric Code has minimum requirements for safe electrical installation, but local building authorities often impose their own codes.
Electrical work must be code-compliant and safe to protect building occupants. When in doubt, contact a licensed electrician.
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Electrical Wiring Mistakes To Avoid
- Making Connections Outside Electrical Boxes
Never connect wires outside electrical boxes. Junction boxes (or J boxes) protect the connections from accidental damage and contain sparks and heat from a loose connection or short circuit.
- Cutting Wires Too Short
Wires that are cut too short make poor wire connections and are thus dangerous. Leave wires long enough to protrude at least 3 inches from the box.
- Leaving Plastic-Sheathed Cable Unprotected
It’s easy to damage plastic-sheathed cable left exposed between framing members. That’s why the electrical code requires cable to be protected in these areas.
Common Household Electrical Issues
- Circuit Breaker Issues
Circuit breakers trip occasionally to prevent overheating and fires from overloads, but a circuit breaker that trips repeatedly indicates a bigger problem. If you notice that your circuit breaker is tripping repeatedly under normal weather conditions and even when you are using only a few appliances, you should contact a licensed electrician to check for bad wiring, ground faults, or other issues.
- Electricity Surges, Sags, or Dips
Surges happen when there’s a spike in charge within power lines, which increases the current to your home’s outlets. Since repeated exposure to surges can damage electronics, use surge protectors. Sometimes surges can’t be helped, like when they’re caused by lightning, but if your appliances surge regularly, you should contact an electrician.
Sags and dips create “brown-outs,” sporadic drops in electrical voltage. Appliances that are plugged into faulty outlets or drawing too much power from an outdated electrical panel can cause sags and dips.
- Scarce or Dead Outlets
A scarcity of outlets can lead to the overloading of existing outlets and rapidly tripping circuits. A temporary solution is to use a heavy-duty extension cord or UL-listed surge protector to extend cord range while you wait for an electrician to install new outlets. Dead outlets either burned out or died due to faulty wiring, and they should not be used. They pose a danger as well as the issues caused by scarce outlets and should be replaced by an electrician.
Become a Licensed Electrician at Erie Institute of Technology
If you are interested in installing and maintaining the systems that power homes, businesses, and factories, you should consider enrolling in the Electrician Program at EIT. Upon completion of this 15-month training program, you will be familiar with the tools of the electrical trade and national electrical code requirements and prepared for a job in the field.
Apply online today or learn more about our skilled trade programs.
Ross Aresco is the CFO of Erie Institute of Technology. Erie Institute of Technology (EIT) is an Erie Pennsylvania technical/trade school providing training programs for medical, computer, electronics, manufacturing, and technology careers. EIT offers programs in many different areas to suit your interests and talents.