A Rudimentary Understanding of Your Electrical System

Disclaimer-Captain DIY and DIYtoFI.blog highly recommend exercising extreme caution when attempting DIY projects. Not everybody can do everything, and some things should only be done by professionals. Keep your digits attached, and keep the insurance company off of your back. Do it right or call the right people!

Hello there, kids! Captain DIY here with a new installment for your devouring pleasure! Today, as the title so aptly suggests, we will be developing your level of understanding as to how the electrical system in your house works. Remember: the more you know, the more you can screw up, so let’s get to learning!

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Got it? Good!

The Brain

The electricity in the wires outside comes down your street at a very high voltage. This is because of voltage drop, which is not something any of us need to know about right now. It is then transformed using a transformer (excellent choice in names) down to the voltage your appliances and lamps can use without blowing up.

This new improved electricity then heads over to your house, where it passes through your meter, which allows the electrical utility company to properly monitor how much they would like to screw you. If you have solar, there is a whole other aspect; it doesn’t affect anything you’ll be dealing with, so we won’t worry about that for now.

The electricity has now found its way into your Circuit Breaker Panel, archaically known as a “fuse-box”, where it can be branched out into what are known as “Branch Circuits”. Again, the people who name things are really killing it here.

Voltage, not Voltron

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Here to save the day. And cook your microwave popcorn.

I get a lot of confusion from customers in my side hustle when it comes to the numbers here. Without getting too deep into sleep-inducing electrical theory, I’ll get into what you need to know about the system specifications in your house.

If you are in the United States, the voltage coming into your house will be 240/120. There are two numbers here for a reason, and I’ll explain that to you right now. This explanation will require a slight touch of sleep-inducing electrical theory, so throw some toothpicks under you eyelids and let’s muddle through it.

The lines coming into your house include two “hot” lines, or lines that have electrical potential (think of these as the water pipes bringing in the water. Water, of course, representing electricity) and one “ground” line. Electricity is always trying to find the easiest path to ground (literally the ground), and we have figured out how to exploit this for our own use.

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Almost there!

AC Voltage, the type we have in our homes, is measure as a sine wave in relation to the flat line that is ground. At the peak of the sine wave, there is a potential of 120 volts to ground, therefore we say the line has 120 volts. The wave fluctuates about 60 times per second, hence the AC (Alternating Current) part of the name.

What about the 240?

We were just about there, hold your horses! The 240 volt measurement comes into play once the second “hot” line is introduced. This one is acting much the same as the first, only the sine waves on the second line are on the opposite side of the spectrum from the first line. In other words, when line #1 is at the upper peak of its wave, line #2 is at the bottom.

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And there you have it

Because they are each measuring 120 volts to ground from opposite sides, the voltage between them is 240 volts. Phew! We made it!

Why is this useful?

Some people may not have any real use for 240 volts in their appliance set up. If you have natural gas, for example, you may only need electricity to control the computer in your dryer and provide a spark to ignite the gas, whereas if your dryer is fully electric (as mine is) your electrical energy demand is far greater.

Voltage and Amperage (also known as current, or “flow” of electricity; think of it as the amount of water flowing through the previously mentioned pipe) exist in a conversely related plane. When the available voltage goes up, the amperage needed goes down. This is what allows your electric dryer to require a mere 30 amp circuit. If it was 120 volts, it would require a 60 amp circuit, and the size of the wires needed to feed it would be far larger (in other words, much more expensive).

On to the nerves

Ok, now that we have a rough idea of what is happening when the electricity comes into our house, and we are feeling a little more confident in our rudimentary electrical theory, let’s get into the stuff we really want to know: the basics of the circuits that make their way around our house.

If you’re looking to change an outlet (“receptacle” in proper trade lingo), you want to know what those wires are inside the box. Well I’ll tell you.

Again, this is geared toward those of us living in the United States. The rest of the world may have many different ways of doing things. Some of you out there may have similar situations, but many of you do not.

So you have gone to your aforementioned circuit breaker box and turned off the circuit feeding the offending receptacle. You pulled the old one off, but you forgot to look at how the wires were attached and now you don’t know what goes where. Fear not! The solution is knowledge, and you’re about to get smacked upside the head with some more of it.

Per electrical code, the “hot” wire, or the one carrying the voltage, will be black, red, or blue. In your house it will almost definitely be black, but I have seen all kinds of colors used by people who just grabbed whatever scrap they had on hand. If you’re in doubt, dig into your tool box and grab your voltage meter and check. This wire gets connected to the brass colored screw.

The neutral wire will be either white or light gray, but again it will almost definitely be white. This is the wire that completes the circuit and allows the electrons to flow. Without this, nothing will happen. This wire gets connected to the silver colored screw. If screw colors are a problem, check if one of the slots on the receptacle face is bigger than the other. This is the neutral; connect the wire to the screw on the corresponding side.

The ground wire (if you have one-if not, that presents a whole new issue. Look for a future post on what to do in that case) will be either green or it will not have any insulation on it at all. This wire exists solely to allow a current spike in the case of a problem. The current spike will cause the circuit breaker to trip, thereby disconnecting electricity and preventing you from getting whacked, bit, shocked, etc. This wire gets connected to the green screw.


The General Gist

The circuit breakers in your electrical panel are simply there to protect the wires that carry electricity throughout your house from overheating. The electricity that flows through them is the same as the electricity flowing through the big cable attached to the outside of your house.

Once it comes to your panel, it gets spread out from there in accordance with assumed use.

Your lights will get a dedicated circuit, your bedrooms will have dedicated circuits, your kitchen counter, bathroom, and garage will get dedicated circuits.

These act as the small twigs holding on to the leaves of the electrical system tree. The trunk is the main power, the first major crotch is the circuit breaker panel, and the branches all spread out from there. Again, the naming folks really crushed it on this one.

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The switches in your house are really just doorways that open and close as you wish, letting electrons flow through or preventing their movement. Even 3-way switches, as complicated as they may seem, are just multiple-path doorways. For the most part, residential electrical systems are very simple.

The More You Know

That’s it, now you know more than the average bear when it comes to your home’s electrical system. We’ve gone over light electrical theory, we’ve talked about sine waves, and we’ve kept up on our knowledge of colors. What a productive day!

As a friend of my family’s likes to say, now you know enough to get into trouble. Remember, this is only scratching the surface of the electrical world, and while I may have made it sound harmless and small, you can still get seriously injured or even killed if you’re not careful. Heck, even if you are careful!

Take this knowledge with you as a tool in your toolbox, and use it as you would any other. Wisely, in the proper setting, and only when necessary. Captain out!

2 thoughts on “A Rudimentary Understanding of Your Electrical System

  1. I don’t see how this is helpful 🙂 Some devices in US use 120 VAC single phase RMS and some three phase setup to benefit from pole to pole voltage of 208 VAC.That is all that you need to know. AC 120 installations other than installing lamp (with screw terminals) is not allowed unless you have have professional permits to do so. Insurance wont cover anything if they find out some amateur has done electric installations after fire if the suspect the electric system was the cause. Low voltage DC installations are allowed to anybody in most countries.(isolated DC systems from normal mains connected AC)


  2. Thanks for the feedback!
    As I’m sure you know, I’m writing this for the residential homeowner DIYer, therefore there is not much need to get into three-phase systems. In the US, which is my home base, the average home uses a single phase 120/240 volt system, and I wrote this article as a way to gain basic knowledge and understanding for someone who has no previous experience with their electrical system, hence the title.
    I live in one of the most strict states in the US in regards to electrical code and licensing, and a homeowner is legally allowed to pull an electrical permit and perform electrical work on their own house. As far as the insurance companies are concerned, I can’t specifically speak to that. There’s a reason my articles are preceded by a disclaimer!


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