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How Electricity Works

Close-Up Of Illuminated Light Bulb Against Black Background

Photo: Getty Images

How Electricity Works

A super simple but useful explanation

Electricity starts with electrons, from whence it gets its name. Electrons are parts of atoms, the stuff that everything is made of. We’ve all seen the classic diagram of an atom, where the nucleus looks like a little planet that’s being orbited by several little moons.

Those orbiting moons are the electrons. They are particles, which means they are things, not energy. Everything that exists is made of atoms, including you and me, and every atom has its little orbiting electrons.

Here’s where the magic happens ... some atoms hold onto their electrons very selfishly, while others are ok sharing electrons with other atoms. So picture a bunch of atoms all lined up in a long row, but instead of the electrons just orbiting each individual atom, imagine a strong wind blowing some of them all along the row of atoms from one to another to another, almost like water passing over stones in a river. When water starts flowing all in one direction we call it a current. And when electrons start flowing all in one direction from atom to atom to atom, we call it ... yes ... an electrical current!

Let’s stick with the water analogy. A river has a lot of energy in it. But the water is a thing, water is not energy. It’s the movement of the water that hides the energy. So, the flow of electrons in an electrical current has a lot of energy in it. But just like the water, the electrons themselves are not energy. Electrons are like drops of water. They are things, not energy. The energy is hidden in the movement itself. It’s the moving water, the current, that has the power. It’s the moving electrons, the current, that has the power.

Whenever we visit New England Tina and I love finding old mills built on the banks of rivers. One of the most romantic images you’ll ever see is a big water wheel gently turning on the side as the water passes by. Also a great way to imagine electricity. If you stick a water wheel down into the current, with some paddles that resist the flow of the current, the energy in the current spins the wheel and makes the mill do it’s work. Energy in the wind spins a wind mill. Energy in the water spins a water mill.

In the same way anything that runs on electricity gets its energy from being “dipped” into an electrical current. Like the paddle on the water wheel it resists some of the energy some of the energy that’s flowing past and that energy is transferred to it. Get it? Remember, our water mill doesn’t consume water. It consumes the energy making the water move. The water itself passes right on by. A light bulb doesn’t consume electrons. They just pass on by. A light bulb consumes some of the energy that is moving the electrons in the current. 

River water flows to the sea and returns to the land again in what we call the water cycle. It’s a circuit. If the water cycle, the circuit, is interrupted, the water ceases to flow. Electricity must flow in a circuit. It doesn’t just flow TO our lights and appliances, it flows THROUGH them and continues on it’s way. If you can understand that, then you’ve taken your first step in truly understanding your home wiring. Every switch, outlet, light and appliance in your home, just like the paddles on the water wheel, are referred to as resistors. And they are all wired along a circuit—a circular path of electrical current that doesn’t end at the appliance, just like the river doesn’t stop at the water wheel, but your electrical current comes from a source to the main panel of your home, runs through your lights and appliances, returns to your panel and back to the source.

So Electricity moves to an appliance, through an appliance, and away from an appliance. Which is why all electrical outlets have at least two slots and all electrical cords have at least two prongs. One side is the flow of electricity to the appliance—we call that the hot side, designated by a black wire. The other side is the flow of electricity from the appliance as it continues on its way. We call that the neutral side and it is designated by a white wire.

So, in your home wiring there is the black wire (hot) bringing electricity to the point of use, and there is the white wire (neutral) returning the current to the panel. Then there is one more wire, usually green or just bare copper, that we call the ground wire. So what’s with the ground and why is it important?

If a river floods and overflows its banks, where does the water go? It doesn’t fly into the air gravity keeps it running on or into the ground. Well, when an electrical current builds up and breaks free of its “banks” (ie: the wires it’s supposed to be traveling in) where does it want to go? Coincidentally, it also wants to go to the ground. Not because of gravity, but because the earth itself is the largest low electrical pressure thing on earth. High pressure always wants to escape into areas of lower pressure. So for all electrical pressure that builds up on or near planet earth, the lowest area of electrical pressure for it to escape to is: planet earth. Or in simple terms: the ground!

So that third wire is called the ground wire because at its other end it is actually connected to the ground. It has no current in it. It has nothing to do with the regular current. It’s there in case of accidents … floods. When electricity jumps beyond its “river bank” it wants to go to ground. The path it will choose to go to ground will be the path of least resistance. It will jump into the most conductive material it can find. Since you are made up of 70% water, and one end of you is usually touching the ground, unfortunately you are often the most conductive material it can find. No one enjoys being the grounding channel for a high voltage electrical current.

But a properly installed ground wire is an even better pathway to the ground than your body so if given the choice the current will discharge through it and not you. That’s how ground wires help keep us safe.

All wires are made of conductive material (like copper) that share electrons and let them flow, coated with insulating material (like rubber) that doesn’t allow current to flow. Hot wires (black) bring the current into your home. Neutral wires (white) let it flow back out. Ground wires are there to provide the best way for accidental rogue current to get to the ground.

And that, my friend, is the essence of home electrical wiring.

Just two more items to add to the system:

At or near the panel the electrical meter (with the glass bowl covering all sorts of readouts) monitors how much energy you use so the power company can send you a bill.

Inside the panel (also known as the service, or the load center, or the fuse box) every individual circuit goes into your home (black) and returns from your home (white) and each circuit has a circuit breaker—a switch that breaks the circular current and therefore shuts off the electricity. Circuit breakers replaced fuses long ago. Circuit breakers are sized to allow a maximum current amperage to flow through them. If a circuit gets an overload of current it trips (automatically cuts off) in order to keep the wiring from melting and the house from catching fire.

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