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Is Household Electricity AC or DC?

Electricity is a necessity for your house to run, but many people do not know how it works. This article will discuss all the details of AC and DC power.

Small white cutout of house with a lightbulb turned on behind it

Electricity is a necessity for your house to run, but many people do not know how it works. However, you may have heard the terms AC and DC without really knowing what they mean. Keep on reading to find out what type powers your house. 

As a general rule, the outlets in your house are almost always AC power. Therefore, transporting AC power across a long distance is easy. In addition, when AC is transmitted at a high voltages, it loses less energy during the transmission. 

If you are interested in finding out more about the electricity in your house, this is the right article for you. We will discuss all the details of AC and DC power. 

What is AC Power?

Blue background, white transformer

Alternating Current (AC) current is how your house or office receives its electricity. It is the standard electricity that comes out of power outlets in homes and buildings. 

This is a wave-like current that flows in a way that can change direction and voltage. It can move from a higher to lower current with the help of a transformer. It powers appliances in your home, like your TV, dishwasher, and anything that is plugged into an outlet. 

AC comes from a power plant. The direction of the AC alternates 60 times a second. In the US, a standard wall outlet is 120 volt, 60 cycle AC power. A transformer is used to change the voltage of the power available.

A transformer allows a high voltage level to send power across long distances. This makes delivering power outlets much easier and faster.

An alternating current wave comes from electrons that flow and move. As they move positively, the waves created by the current move up. When the electrons move negatively, the wave moves down. An alternator located in a power plant creates the waves, which makes the AC power. 

How is AC Power Generated?

Night time, large generator sitting out on grass, light shining on it

The alternator is a critical piece for generating AC power. An alternator creates the waves for the AC power. There is a magnetic field inside the alternator that has a wire loop that spins inside it. 

As the wire spins, it moves into different areas of magnetic polarity, which creates alternating waves of current. There are many ways to create the rotation of the wire. It can be by a steam turbine, wind turbine, water, and other means. 

What is DC Power?

Black direct current cords

Direct current (DC) power is produced by a battery, alternator, fuel cell, or solar cells. The current always moves in the same direction between the positive and negative terminals. The positive terminal always remains positive, and the negative terminal is always terminal.

The batteries in mobile devices, laptops, toys, etc., operate with DC power. DC power moves in one direction in a linear, or straight, line. This movement is how DC current gets its name. DC power consistently is known to deliver power at the same voltages every time, making it ideal for electronics.

DC power can also be created from AC power with the help of a rectifier. Many electronics use batteries or a rectifier converts AC power to DC power. 

How is DC Power Generated?

Gray, red and black high power battery

Direct current power can be generated in a few different ways. In general, batteries provide DC power because of the chemical reaction that occurs inside of the battery. As mentioned previously, a rectifier can convert AC to DC current. 

A piece of equipment called a commutator is found within an AC generator. The commutator is able to produce a direct current. 

What is AC/DC Power?

Close up of an electric car charging station

Have you ever noticed that the power cord for your laptop has a little box, or power adaptor, somewhere between the end that plugs into the outlet and the one that plugs into your laptop? 

This power adaptor converts the AC wave coming from the outlet to steady DC power before it provides the juice for your laptop or charges the battery for your laptop. This is what allows your laptop to use a combination of AC/DC current. 

Some electronic devices, like laptops, have delicate components that are easily damaged by fluctuating currents. This is why DC is preferred. However, laptops are not the only item you will find around the house that uses a combination of AC and DC applications. 

Many iPhone users have affectionally called the block they plug their power cord into a brick. That brick acts as a power adaptor to convert AC to DC. This combination also is ideal for powering electric motors, as well as some vehicles. 

You can also find AC/DC power supplies. They look similar to a surge protector. Most of the time, they are a combination surge protector and power adapter. These units contain a transformer to change the voltage and a rectifier to convert the power to DC. 

They usually contain filters to remove some of the electric noise created from having high and low waves. The waves remain even as the power changes from AC to DC, which creates an output voltage ripple of higher and lower voltages.

Why Are There Two Types of Power?

The simple answer is that DC power comes from AC power. While that is true, most of the electronics we use today prefer even voltage and smooth flow of electricity that is common with DC power. This makes both types necessary. 

AC power is dominant because this is the power that is brought into houses and buildings. Even if the current is going to be transformed into DC immediately, it still begins as AC. This is because direct current power does not have the capability of traveling the long distance from power plants to homes as alternating current power does. 

Alternating current power is easy to generate because of the way that generators turn. As a result, it is more affordable to operate AC power. AC power is moved by national power DC grids across miles of wires.

Direct current power is more critical at the site of the device that needs power, especially when that device stores power in a battery to use later. In short, anything that uses a battery is heavily reliant on the constant voltage of DC power.  

Converting AC to DC power is not the only way to charge a battery, in your smartphone, for example. Think about when you have used a power bank to charge your phone. You may have called it an external battery or external charger. It can go by many names. 

Regardless of what you call it, the concept is the same. The power bank is basically a battery that has DC power. You can charge the power bank, but once it is charged, it can charge your phone. When you charge your phone, you are using DC power to charge it. 

Most likely, the power bank will need to change the output voltage because the power bank voltage may be different than the phone. However, this is an instance of DC/DC power. 

As you can see, they are both essential and needed. We have both of them today because of the War of Currents back in the 1880s and 1890s. Thomas Edison used DC voltage for his lighting system, while George Westinghouse used AC voltage for his. 

While their battle over which voltage was best led to some heated debates and accusations, ultimately, it created a space for both AC and DC power.