Home Electrical Wiring Systems

The Basics of Home Electrical Wiring Systems and Working with Electricity in the Home

By Mark J. Donovan

Recently we lost our electrical power to our home for 10 days due to a major ice storm in the New England area. It was during these 10 days that I had a chance to fully appreciate the dependency our society has on electrical power and our home’s electrical wiring system. In my particular situation, our home has its own private well and leach-field/septic system, uses oil for hot water heating, and requires electricity for the range/oven to operate. The loss of electrical power meant the loss of water, sewage, home heating, and the ability to cook since all required electrical power to operate.

Fortunately, we had a gas heater to brave the cold days and nights, and after 8 days I was able to purchase a portable generator. The portable generator enabled us to provide the basic requirements of survival including heat, water, and food.

It was during the temporary and then permanent integration of the portable generator into our home electrical wiring system that I realized that besides the dependency on electrical power, many homeowners lack a basic, yet significant, knowledge of their own home’s electrical wiring system.

Consequently I thought it might be useful to highlight a few key topics associated with home electrical wiring. However, it is important to keep in mind that the electricity entering and running throughout your home is extremely dangerous and can electrocute and kill you if you come in direct contact with it. Consequently it is important to exercise extreme caution when working with your home’s electrical wiring system.

The Flow of Electricity throughout your Home’s Electrical Wiring System

Electricity Entering the Home

To begin with, high voltage electricity comes in from the telephone poles or underground wires via a transformer. The transformer (which is typically a large gray cylindrical canister that sits on the telephone pole) steps down the high voltage line wire to a 120V AC (Alternating Current) level.

This high voltage, and the current associated with it, enters your home’s electrical wiring system via a main circuit panel that sits typically in your basement, garage, or utility room.

Here is an electric bux for a light.

Main Circuit Panel / Circuit Breaker

The electricity coming into the main circuit panel is allowed to feed various circuits in the main circuit panel via a main circuit breaker. The main circuit breaker is typically rated to allow up to 100 to 200 Amps of electricity through it before automatically shutting down in the event of a short or over-use condition.

Circuit Breakers

Once the electricity makes it through the main circuit breaker in the main circuit panel it flows to various circuit breakers in the panel that then send electricity to various electrical wiring circuits throughout the home.

The circuit breakers are rated for different current and voltage levels, e.g. 15 Amps, 20 Amps, and 30 Amps, at 120V or even 240V AC. Again, these circuit breakers can be “tripped”, or automatically shut off, if too much current is attempted to flow through them. If too much current was allowed to flow through them, the wires that make up the circuit and feed the electrical appliances throughout the home could heat up and cause a fire.

GFCI Breakers

In addition to the standard circuit breakers there are also GFCI (Ground Fault Circuit Interrupter) breakers that are used for circuits in your home that are in close proximity to water, e.g. your kitchen, bathroom, garage, and basement.
These types of circuit breakers can sense the ever slightest rapid change in current draw, or ground fault condition, and trip, thus shutting off power to the circuit. GFCI breakers are made to protect people from being electrocuted and possibly killed otherwise.

Hot and Return Wires

After the electricity leaves a circuit breaker it flows out via “hot” insulated wires, normally black or red wires that are encased in plastic or metal sheathing. From there these wires connect to electrical outlets and switches, and eventually to lights and electrical appliances.

The current flows through these appliances and returns back to the electrical outlets to “Return” insulated wires, normally white wires. The “Return” wires then feed back to the main circuit panel and connect to a bus bar that ties all of the “Return” wires and ground wires together. The bus bar is also tied to “Earth ground” typically via a large copper wire that is attached to a copper ground wire that is buried in the ground several feet, next to the home.

Ground Wire

In addition to the “hot” and “return” wires that flow from the main circuit panel to the various circuits in the electrical wiring system throughout the home, there is an additional bare copper wire referred to as a “Ground” wire. This “Ground” wire attaches to the various electrical appliances via the electrical outlets. The “Ground” wire should never have any current flowing on it, however in the event of a short in the electrical appliance current will flow through it and immediately cause the associated circuit breaker to trip thus shutting of power to the circuit and preventing the possibility of fire and potential electrocution.

Electrical Sheathing Wire

The home electrical wiring that is fed between the circuit breakers in the main circuit panel and the various circuits throughout the home is referred to as Electrical Sheathing Wire. It is frequently referred to as Romex wire due to a particular manufacture of this type of wire. Encased in the sheathing are the “Hot”, “Return” and “Ground” wires.

Use of Electrical Testers

Again, working with home electrical wiring systems is dangerous, however with some basic electrical wiring knowledge and making sure the appropriate circuit breakers are turned off first, homeowners can tackle smaller home electrical wiring projects, such as installing dimmer switches and ceiling fans. It is wise, however, to first use a Neon tester or Digital Multimeter when working with home electrical wiring systems to make sure electricity is indeed turned off at the specific electrical outlet or switch prior to actually touching it.

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