Home Electrical Systems: How Are Homes Wired?

Home Electrical Systems consist of a line, a meter, the main circuit breaker, separate wiring circuits to the rooms in the home, outlets, light fixture boxes and various appliances. Here is a short, easy guide to home electrical systems.

Home Electrical Systems: The Meter

Typically, the main line comes from a pole or underground. It connects to the home, where it meets the meter, which is usually on the exterior of the home. Most are mechanical and have a spinning wheel, as well as a mechanical display of numbers; some newer models have an LCD screen. This is utility company meter-readers use when visiting your home. The meter gathers data on the electricity used each month, measured in kilowatt hours. The increase each month is the number the utility company uses to generate your bill.

Home Electrical Systems: The Main Breaker Panel

Most main breaker panels in home electrical systems are inside the home, while it is possible to have weather-proof panels on the exterior. The main electric supply line moves from the meter to the main breaker panel when entering the home, at the main circuit breaker. The size of the main circuit breaker determines the maximum electricity that a home can use at any given time. It is a kind of switch that turns off in the event of an overload, which reduces the risk of fire or electrocution.

Most newer homes use a two hundred amp service, older ones might only use a one hundred amp service, and a larger home can use as much as four hundred amps. If you would like to know how much your home uses, you can just take a look at the main breaker panel. If you open it and look for the largest breaker switch (which is usually near the top), you will see the total amps of your home electrical systems.

Home Electrical Systems: The Circuits

After the home electrical systems distribute power through the circuit breakers, they run through bundles of wires in the walls, floors, and ceilings in each room and through to hard-wired appliances. Each bundle contains at least three wires two with plastic insulation and one which is bare. Black and red insulated wires are “hot” wires, which come directly from the circuit breaker. The white wire is the “neutral” which brings the current back to the electrical source in the panel. The bare wire is a copper ground wire, the safety part of the circuit. The ground wire is a direct path to the ground, acting with the circuit breaker if there should be a short circuit. It acts as a path of least resistance for excess electricity.

The insulated wires are attached to outlets or switches and when nothing is plugged in or the switch is off the wires do not meet. But, when you plug anything into an outlet or the switch is turned on, the circuit is complete and allows electricity to flow through a light or appliance.

Home Electrical Systems: GFCIs and AFCIs

After the breaker system, the most common safety precaution is the Ground Fault Circuit Interrupt (GFCI) outlet. It senses when someone begins to receive a shock and shuts off the electricity within milliseconds, preventing potential electrocution. You can usually find these in locations that might use water; like bathrooms, kitchens, garages, basements and outdoors. These appear to be regular outlets, but they have a test and reset button. If the GFCI is tripped, the reset button restores power if the problem is fixed. Because they have sensors, which can fail occasionally, you should test them to ensure they are still functioning well. You can press the test button and then press the reset button to restore the power.

While GFCIs are great, they do have faults. And one of them is an electrical arcing. This is when metal or water complete a circuit outside of it’s intended circuit, and the fault is less direct. While a GFCI can detect a dead short, it cannot detect an electrical arcing. Arcing can occur where there are loose connections, and where furniture meets electrical cords; even inside your walls. Only Arc Fault Circuit Interrupts, or AFCIs, can prevent this type of hazard. The National Electrical Code requires AFCI outlets in many areas of the home including family rooms, dining rooms, living rooms, bedrooms, closets, hallways, sunrooms and similar rooms or areas. You can read more about it here.

Hire a Professional

Home electrical systems are very complex and only a professional should make repairs. You do not want to take the chance of making a bigger problem than you have or even hurting yourself. You can start your search here.