How the Household Power System Works

Power comes to your house through power lines that run along the street. At the end of these lines is a large metal box with a hinged cover called the meter/breaker (or fuse) panel.

Whole-home battery storage systems provide security during power outages and allow homeowners to reduce their reliance on grid energy at peak times. They’re becoming more practical as battery technology improves and financial incentives become available [35].

The Wires

Power comes into our homes over large high-voltage transmission lines that may run miles to a substation, where the voltage is lowered on smaller transformers so it can travel over distribution lines to our neighborhood. Then the electricity goes to each home on separate poles and enters through a meter mounted outside, monitored by the electric company (tampering with the meter is illegal). The electricity then travels through wires in your walls to outlets and switches all over your house.

Most of the wires Household Power System in your household carry 120- to 240-volt circuit voltage, which can be dangerous to touch. A few carry lower-voltage currents and are not considered hazardous, but all electrical wiring should be treated as dangerous until proven otherwise.

The hot wires, which carry electricity to the various fixtures and appliances in your house, have insulation that is black or red or some color other than white. Contact with a hot wire should shock you. The neutral wires (usually white or gray) carry electricity back to the service panel.

The ground wire, which carries electricity to the earth, is usually bare or has green insulation. It connects to the ground bus bar in your service panel, as well as any other grounded or bonded wires in your system. When contact with a ground wire occurs, it tends to redirect the flow of current elsewhere, preventing serious shock.

The Meter

When electricity enters your house, it passes through the meter that records how much power you use. It then travels through wires to outlets and switches in your house. To keep the flow of current flowing, the wires and receptacles must form a continuous loop that’s not broken or shorted. This loop is called a circuit.

Most modern meters are digital in design, but old mechanical “meter movements” still use a pointer to display the measured value of voltage, current or resistance. Both designs are based on the principle that electric current passing through a conductor creates magnetic fields perpendicular to the direction of flow. The more current flows, the stronger the magnetic field. The pointer is connected to a display that shows the value of the measurement, with zero on the left and full scale on the right. A rise in the measured current drives the needle further toward the right, while a fall causes it to move back to the left.

The meter is one of the seven basic units of the International System of Units, the world’s standardized measurement system. Since the 1960s, all countries have adopted or legalized the SI, easing global trade and scientific exchange of data. The meter is also an important part of the global network of atomic clocks that enable accurate timekeeping.

The Switches

The electrical system in most homes is set up with a series of circuits that each contain a hot wire that powers lightbulbs, appliances and other receptacles, plus a neutral wire that returns the electricity to the main panel. Each circuit is backed by a fuse or circuit breaker that can shut off the power to individual outlets, lighting, switches and other fixtures in case of a short or overload. In some cases, there is a separate “main” breaker that can shut off all of the breakers in the main panel.

There are several types of switches, including simple on-off switches and rotary switches that provide Household Power System greater pole and throw capabilities. Some switch designs have spring mechanisms that make sure the transition between on and off is short, regardless of how quickly you move the rocker.

There are also switches that allow you to control a single light or receptacle from two different locations, called three-way switches. These switches do not have on/off markings, because the on and off positions will change as you use them. Three-way switches are usually used in pairs, and their terminal screws include three positions: the common screw, which always connects to the hot wire; the traveler wires, which each connect to one of the other two switch positions; and the polarity-reversing switch, which can connect to L1, L2 or both.

The Outlets

Turning on the lights, popping a frozen dinner in the microwave or flipping on the TV seems like such an everyday occurrence that it’s easy to overlook what needs to happen behind the scenes to make those things work. Knowing how electricity works is crucial in order to understand how it gets to your home and what happens within the walls of your house that allows you to plug in your devices.

The power coming into your house starts at a power plant, travels on large power lines to a substation where the voltage is lowered to make it safe for residential use. Then, it travels through smaller distribution lines to your neighborhood, where it is turned up again by transformers to run your appliances and lighting.

Your house is equipped with outlets (also called receptacles) where you plug in your appliances and devices. They come in a variety of configurations, but the most common are 15-amp outlets, also known as standard outlet or two-pronged receptacle. These outlets have a longer vertical slot for the hot wire and a shorter horizontal slot for the grounding pin.

For more powerful appliances such as a washer, dryer or electric stove, you’ll need to use 20-amp or higher outlets. The third pin on these outlets acts as a safety ground, which reduces the risk of electrical shock should you come in contact with water or an exposed live wire. Other types of outlets include combination outlets, tamper-resistant outlets and arc fault circuit interrupter outlets. These outlets constantly track current flow and will trip (or cut off power) when they detect a surge, which can prevent overheating or damage to your equipment.