Learn the Basics of Your Home's Electrical System (2023)

Home Improvement



Timothy Thiele

Timothy Thiele

Timothy Thiele has an associate degree in electronics and is an IBEW Local #176 Union Electrician with over 30 years of experience in residential, commercial, and industrial wiring.

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Updated on 06/15/22

Reviewed by

Larry Campbell

Learn the Basics of Your Home's Electrical System (1)

Reviewed byLarry Campbell

(Video) Understanding Your Home's Electrical System: The Main Panel

Larry Campbell is an electrical contractor with 36 years of experience in residential and light commercial electrical wiring. He worked as an electronic technician and later an engineer for the IBM Corp. is a member of The Spruce Home Improvement Review Board.

Learn more about The Spruce'sReview Board

Fact checked by

Jillian Dara

Learn the Basics of Your Home's Electrical System (2)

Fact checked byJillian Dara

Jillian is a freelance journalist with 10 years of editorial experience in the lifestyle genre. She is a writer and fact checker for TripSavvy, as well as a fact-checker for The Spruce.

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People depend on electricity constantly, and when the power goes out in a storm or there's a tripped breaker oranother problem in anelectrical circuit, understanding the basic components of an electrical systemcan help you get things running again. It's also important to know who is responsible for what portion of your electrical service. The utility company handles the line portion of your service, which includes everything up to the attachment point on your house. From there, it's called the load side, and everything on the load side is your responsibility.

  • 01 of 09

    Electrical Service Connection and Meter

    Learn the Basics of Your Home's Electrical System (3)

    Your home's electricity starts with the power service and electric meter. The utility company's service cables (whether overhead or underground) extend to your house and connect to the utility's meter base. The electric meter plugs into this meter base. The meter measures the amount of electricity your home uses and is the basis for the charges on your electric bill.The meter runs only when electricity is used in the house.

  • 02 of 09

    (Video) Electrical Wiring Basics

    Disconnect Switch

    Some home electrical systems include a dedicated disconnect switch that is mounted on an outside wall of the home near the electric meter. In the event of a fire or flash flood, or if work needs to be done on the system, a disconnect switch allows you to shut off the power from outside the home so you don't have to enter the home to turn off the power. If an electrical system does not include a separate disconnect switch (and most do not), the main circuit breaker in the home's main service panel (breaker box) serves as the system disconnect.

  • 03 of 09

    Main Service Panel

    Learn the Basics of Your Home's Electrical System (4)

    After passing through the meter, your electrical service feeds into your home'smain service panel, commonly known as the breaker box. Two large "hot" wires connect tobig screw terminals, called lugs, inside the service panel, providing all the power to the panel. A third service wire, the neutral, connects to the neutral bus bar inside the panel. In simple terms, electricity is supplied to the house on the hot wires. After it flows through the household system, it is fed back to the utility on the neutral wire, completing the electrical circuit.

  • 04 of 09

    Main Circuit Breaker

    The service panel contains a largemain breaker that is the switch controlling the power to the rest of the circuit breakers inside the panel. It is sized according to your home's service capacity. A standard panel today provides 200-amp (ampere) service. Older panels were sized for 150, 100, or fewer amps (amperes).

    A main breaker of 200 amps willallow a maximum of 200 amps to flow through it without tripping. In a tripped state, no current will flow to the panel. In systems without an external disconnect switch, the main breaker serves as the household disconnect.

    Turning off the main breaker stops the flow of power to all of the branch circuit breakers in the panel, and therefore to all of the circuits in the house. However, power is always flowing into the panel and to the service lugs even when the main breaker is shut off unless the power is shut off at a separate disconnect switch. Power is always present in the utility service lines and the electric meter unless it is shut off by the utility.

    Continue to 5 of 9 below.

  • 05 of 09

    Branch Circuit Breakers

    Learn the Basics of Your Home's Electrical System (5)

    The breakers for the branch circuits fill the panel (usually below) the main breaker. Each of these breakers is a switch that controls the flow of electricity to a branch circuit in the house. Turning off a breaker shuts off the power to all of the devices and appliances on that circuit. If a circuit has a problem, such as an overload or a fault, the breaker automatically trips itself off.

    The most common cause of a tripped breaker is a circuit overload. If you're running a high-demand appliance, such as a vacuum, toaster, or heater, and the power goes out, you've probably overloaded the circuit. Move the appliance to a different circuit and reset the breaker by switching it to the ON position. If the breaker trips again—without the appliance plugged in—you must call an electrician. There may be a dangerous fault situation in the circuit.

    (Video) Understanding Electrical Systems at Home | Electricity

  • 06 of 09


    Learn the Basics of Your Home's Electrical System (6)

    Devices are all the things in the house that are connected to electricity, including switches, receptacles (outlets), light fixtures, and appliances. Devices are connected to the individual branch circuits that start at the breakers in the main service panel.

    A single circuit may contain multiple switches, receptacles, fixtures, and other devices, or it may serve only a single appliance or receptacle. The latter is called a dedicated circuit. These are used for critical-use appliances, such as refrigerators, furnaces, and water heaters. Other appliances, such as dishwashers and microwaves, usually are on dedicated circuits, too, so that they can be shut off at the service panel without interrupting service to other devices. This also reduces the incidence of overloaded circuits.

  • 07 of 09


    Learn the Basics of Your Home's Electrical System (7)

    Switches are the devices that turn on and off lights and fans in your home. They come in many different styles and colors to suit your design needs. There are single-pole, three-way, four-way, and dimmer switches. When you flip a switch off, it "opens" the circuit, meaning the circuit is broken or not complete and the power is interrupted. When the switch is on, the circuit is "closed," and power flows beyond the switch to the light or another device it is controlling.

  • 08 of 09


    Learn the Basics of Your Home's Electrical System (8)

    Electrical outlets, technically called receptacles, provide power to plug-in devices and appliances. Televisions, lights, computers, freezers, vacuums,and toasters are all good examples of devices that can be plugged into an outlet. Standard outlets in a home are either 15-amp or 20-amp; 20-amp outlets can provide more electricity without tripping a breaker. Special outlets for high-demand appliances, such as electric ranges and clothes dryers, may provide 30 to 50 or more amps of power.

    In potentially wet areas of a home, such as bathrooms, kitchens, and laundry rooms, some or all of the outlets must have GFCI (ground-fault circuit-interrupter) protection, provided by GFCI outlets or a GFCI breaker.

    Continue to 9 of 9 below.

  • 09 of 09

    (Video) Home Electrical 101 - What you need to know now!


    Your home’s wiring consists of a few different types of wiring, including non-metallic cable (commonly called Romex), Bx cable, and wiring concealed in conduit. NM cable is the most common type of circuit wiring. It is suitable for use in dry, protected areas (inside stud walls, on the sides of joists, etc.) that are not subject to mechanical damage or excessive heat.

    Bx cable, also known as armored cable, consists of wires running inside a flexible aluminum or steel sheath that is somewhat resistant to damage. It is commonly used where wiring for appliances, such as dishwashers and garbage disposals, is exposed.

    Conduit is a rigid metal or plastic tubing that protects individual insulated wires. It is used in garages, sheds, and outdoor applications where the wiring must be protected from exposure.

    Wires running inside NM cable, Bx cable, or conduit are sized according to each circuit's amperage. Wire size is given in its gauge number. The lower the gauge, the larger the wire, and the more current it can handle. For example, wiring for 20-amp circuits is 12-gauge, which is heavier than the 14-gauge wiring used for 15-amp circuits.


  • How do I shut off the electric in my house?

    If you want to turn off the electric to the entire house, go to your home's service panel box and flip the switch for the main breaker to off.

  • Why did the circuit breaker trip?

    Circuit breakers can trip for a few reasons. The most common reason a circuit breaker trips is because of an overload. It can also trip due to a short circuit, ground circuit, or Arc fault.

  • Where do GFCI outlets need to be installed in a house?

    GFCI outlets should be installed in bathrooms, kitchens, laundry rooms of all homes and the National Electric Code (NEC) requires them in garages and basements or where receptacles are within six feet of water in new construction.

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  1. Home Electrical Fires. National Fire Protection Association

    (Video) How ELECTRICITY works - working principle


Is my house 110v or 220v? ›

Most houses today have two 110 volt wires and one neutral wire running into the house from the local distribution system. These wires can run underground or above ground. If there are two 110 volt wires running to the house, then the house has 220 volt service and appliances, such as dryers and air conditioners.

What are the two major faults of an electrical system? ›

The faults in the power system are mainly categorized into two types: Open Circuit Fault. Short Circuit Fault.

Does a dishwasher run off 110 or 220? ›

1-3 of 3 Answers

The dishwasher operates at 110 volts.

Are fridges 110 or 220? ›

Refrigerator – Most refrigerators work with a standard 100-120 volt electrical plug and outlet. You will notice that the electrical plug is made up of three prongs; this means you will need an electrical outlet that has three inserts.

Can a stove run on 110? ›

When it comes to electricity usage, an electric stove is a powerhouse. Consequently, you can't just plug them into the standard 110-volt outlets that are most common in the United States—most stoves require a special 220-volt outlet instead.

What is the #1 safety rule electricians must follow? ›

The very first thing you should do when beginning an inspection or repair job is turn off the current at the switch box and padlock the switch in the off position. The same applies to any equipment or machines you may be servicing.

What are the golden rules of electrical safety? ›

Never walk past unsafe acts or conditions. Never remove, bypass or modify a safety device without authorisation. Never enter a delineated hazardous area without authorisation.

What is the 1 rule of electrical safety? ›

The first rule of electrical safety is to always disconnect whatever you're working on. This might mean unplugging an appliance that requires repairs or turning off a circuit breaker. You must disconnect before performing any electrical work to reduce the risk of electrocution.

What color wire is hot? ›

Here's a rundown of electrical wires: The black wire is the "hot" wire, it carries the electricity from the breaker panel into the switch or light source. The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel.

What is electrical checklist? ›

Electrical Inspection Checklists (Checking, Verifying and Reviewing Electrical Installations) The checklists are intended to help inspectors keep track of the numerous aspects of an electrical installation that must be checked, verified, reviewed, determined, or otherwise examined for NEC® compliance.

What is the most common wiring problem in electrical systems? ›

Electrical surges

It usually occurs due to poor electrical wiring in the house, faulty appliances, damaged power lines, or when lightning strikes. Electrical surges are common electrical problems, and they last for a split of a second.

What are the 3 wiring faults of a circuit? ›

There are mainly three types namely line to ground (L-G), line to line (L-L) and double line to ground (LL-G) faults. Line to ground fault (L-G) is most common fault and 65-70 percent of faults are of this type. It causes the conductor to make contact with earth or ground.

Are wall outlets AC or DC? ›

When you plug things into the outlet in your house, you don't get DC. Household outlets are AC - Alternating Current. This current has a frequency of 60 Hz and would look something like this (if you plotted current as a function of time).

Do dishwashers need to be on a GFCI? ›

Kitchen dishwashers installed in dwelling units require GFCI protection whether hard wired or cord and plug connected. Code Change Summary: A new subsection was added regarding dwelling unit kitchen dishwashers. Now, outlets that supply dwelling unit kitchen dishwashers must have GFCI protection.

Can a dishwasher be on the same circuit as kitchen outlets? ›

It is not uncommon, for example, for a kitchen to have only two or three circuits, and for basic appliances such as the refrigerator, dishwasher, garbage disposal to be powered by the same general-purpose circuit that powers the light fixtures and countertop receptacles.

Do I need a junction box for my dishwasher? ›

Many permanently installed appliances, such as kitchen vent hoods, dishwashers, and hot water heaters, also don't require junction boxes.

Should a refrigerator be on 15 or 20 amp outlet? ›

Most refrigerators use between 3 and 6 amps, but peak draw can spike up to 15 amps. For this reason, refrigerators and freezers should be connected to a 15-20 amp dedicated 120-volt circuit.

Is a GFCI required for a refrigerator? ›

All commercial buildings/kitchens are required to have GFCI for refrigerators. See NEC 210.8(B)(2). In a Dwelling Unit (house or apartment) refrigerators located inside the kitchen do NOT have to have a GFCI.

How many refrigerators can be on a 20 amp circuit? ›

How Many Refrigerators Can Be on a 20 Amp Circuit? You can connect up to two standard refrigerators in the same circuit. Two standard refrigerators will draw about 12 amps of power, which is below the recommended 80% capacity of a 20-amp circuit.

What happens if you plug a 220V oven into a 110V outlet? ›

If you plug a 220V device into 110V outlet, it will normally last a little longer before it dies. But: An AC mechanical drive may fail to start, or it may take up more current than it is designed for, and eventually burn out. The insulation is usually not a problem unless there is a major flaw in the design.

Do dryers run off 110? ›

110 volts is okay for washers. If you buy an electric dryer then you'll need 220 volts.

Do stoves have to be GFCI? ›

In dwellings, the code now extends the GFCI requirement to 125-volt and 250-volt receptacles in finished and unfinished basements, within six feet of a sink, and laundry areas. For example, with this new criteria, electric dryers and kitchen ranges within six feet of a sink will require GFCI.

What is the first rule of electricity? ›

Rule 1 – Electricity will always want to flow from a higher voltage to a lower voltage.

What is the most important rule of electrical? ›

Disconnect Power Source

This is the very first important rule to follow. This is the very first important rule to follow. Make sure to first disconnect the device from the power source if you're ever going to work on an electrical appliance in the home. It may not be enough to just switch it off.

What is the 5 point safety system? ›

August 2020) The Neil George Safety System (or 5-Point Safety System) is an occupational health and safety program developed, used in underground mining. The system was developed in 1942 by Canadian engineer Neil George, who at the time was an employee of Inco Limited in Sudbury, Ontario.

What is the 80% rule in electrical? ›

The 80% (standard-rated) breaker can only be applied continuously (defined as 3 hours or more by the NEC) at 80% of its continuous current rating (or Ir setting; e.g. if a 150 A H-frame is dialed to 100 A, the 80% rating applies to the 100 A setting).

What is thumb rule in electrical? ›

Thumb Rules. Cable Capacity. For Cu Wire Current Capacity (Up to 30 Sq.mm) = 6X Size of Wire in Sq.mm. Ex. For 2.5 Sq.mm = 6×2.5 = 15 Amp, For 1 Sq.mm = 6×1 = 6 Amp, For 1.5 Sq.mm = 6×1.5 = 9 Amp.

What are some basic rules for an electrical wiring system? ›

There is a white wire that is the “neutral,” and, finally, a bare copper wire that is the ground wire. When electrical wires are joined together the black wires must be hooked together, the white wires must be hooked to the white wires, and the ground wires must be hooked together.

What color electrical wires go together? ›

The protective ground is green or green with yellow stripe. The neutral is white, the hot (live or active) single phase wires are black , and red in the case of a second active.

Which wire is positive if both are black? ›

Wire Colors for DC Power

The red wire is positive. The black wire is negative. The white wire (if present) is ground (sometimes called neutral in DC). If both wires are black but one has a white stripe, the striped wire is negative, while the plain black wire is positive.

What voltage causes the most fatal shocks? ›

A good rule of thumb is that when a shock is at or above 2,700 volts, the person often dies or experiences severe injury. At over 11,000 volts, the victim will usually pass away.

What are the 3 primary hazards when working with electricity? ›

The major hazards associated with electricity are electrical shock, fire and arc flash.

What is the most serious electrical hazard? ›

Old, worn-out or defective electrical wiring is one of the most common – and dangerous – home electrical hazards, and has the potential to result in power surges and electrical fires.

What is simple checklist? ›

What is a simple checklist template? A simple checklist template is any kind of process or list of tasks arranged in the form of a checklist; in other words, it's a to-do list where the order of tasks is usually important.

What is the greatest single cause of electrical failures? ›

Since loose connections are the number one leading cause for electrical failures by contributing to over 30% of all electrical failures and are a major cause for power outages, we've devised a solution to monitor those failure points and prevent unexpected downtime.

What is the number 1 cause of electrical fatalities? ›

Arc-flash safety is important, however, the electrical industry's deadliest act—electrical shock—is often left forgotten. More than 90% of electrical fatalities among US workers are due to electrical shock.

What causes electrical problems in home? ›

It usually occurs due to poor electrical wiring in the house, faulty appliances, damaged power lines, or when lightning strikes. Electrical surges are common electrical problems, and they last for a split of a second. If there are frequent surges, they can damage the equipment and lower its life expectancy.

What is the most common electrical hazard? ›

The following hazards are the most frequent causes of electrical injuries: contact with power lines, lack of ground-fault protection, path to ground missing or discontinuous, equipment not used in manner prescribed, and improper use of extension and flexible cords.

Which is the most common fault in the power system? ›

Line to ground fault (L-G) is most common fault and 65-70 percent of faults are of this type. It causes the conductor to make contact with earth or ground. 15 to 20 percent of faults are double line to ground and causes the two conductors to make contact with ground.

What are the three keys of electrical safety? ›

Follow safe work procedures at: bchydro.com/safetytraining, worksafebc.com, and bconecall.ca. Keep at least 10 metres back from fallen power lines. Treat all power lines as live and extremely dangerous. Stay put and do not attempt a rescue.

What are the 4 types of electrical shock? ›

There are four main types of electrical injuries: flash, flame, lightning, and true. Flash injuries, caused by an arc flash, are typically associated with superficial burns, as no electrical current travels past the skin.

How many volts is lethal? ›

A good rule of thumb is that when a shock is at or above 2,700 volts, the person often dies or experiences severe injury. At over 11,000 volts, the victim will usually pass away.

What voltage causes the most fatalities? ›

It is sometimes suggested that human lethality is most common with alternating current at 100–250 volts; however, death has occurred below this range, with supplies as low as 42 volts.

What controls the electrical system in a house? ›

Main Circuit Breaker

Within your service panel is a large main breaker. This main circuit breaker is a switch that controls power to the rest of the circuit breakers in the panel. Its size depends on the electrical service capacity of the home.

What are the signs of an electrical problem in your home circuit? ›

Look and Listen for Flickering, Buzzing or Dimming Lights

If your lights buzz when they're turned on or flicker/dim when you use multiple appliances, this is a definite sign that you're home's wiring requires a professional upgrade.


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