Many of us will take the electronics in our homes completely for granted. We all appreciate the lights, plug sockets and many other utilities that we use in our homes on a daily basis.
However, when it comes to the wires and circuit breakers that provide the electricity for these appliances, few of us will ever think about them until something goes wrong.
When something does go wrong, it can be difficult to know how to approach the issue.
Often the best course of action is to call a professional electrician, although some people may be tempted to give it a go themselves.
If you are DIY minded, then you should be warned that live electronics are no joke, and you should always exercise caution when tinkering with them.
That said, there is nothing wrong with understanding the wires and cables that power your home.
Whether you want to try your hand at being an electrician, or just want to know more about how power flows into and around your house, then you have come to the right place.
This article will aim to explain the different colors of wire and what they mean.
We will also cover the different varieties of circuit breaker and how to choose the right kind of wire for connecting to each one.
Table of Contents
Useful Tools For Handling Electric Circuits
If you do plan to wire up a circuit breaker by yourself, or perform any other kind of DIY electronics, then you should read this section to find out what kind of equipment you will need.
Playing with electrical circuits should never be done lightly, especially if they are connected to the mains.
A wrong move could result in a significant electric shock, or even worse, so always be careful.
If at any point you are uncertain of what you are doing, then stop and call a professional electrician.
That said, if you do have a bit of experience with electronics and know the risks then you can often do your own wiring with just a few simple tools.
Approved Voltage Indicators
An approved voltage indicator or AVI is an essential tool for anyone looking to do their own electrician work.
These devices are used to detect if an AC current is present or not at a specific section of a circuit or at a plug socket.
They play an important part in double-checking that a circuit or appliance is dead before you start work on it.
Even if you are certain that you turned off power to the area where you are working, you should always double-check the circuit is actually dead using your AVI.
It might take a little extra time, but it is worth it to avoid giving yourself a nasty electric shock. Note that an AVI is not the same as a multimeter.
While you could feasibly use a multimeter to prove that a circuit is dead, it is not recommended.
This is because multimeters test for a variety of other parameters as well as voltage.
If you choose the wrong parameter to measure, you could end up convinced a circuit is dead when it is not.
A good set of tools is vital if you are going to be working on the electrics in your home.
You want to make sure you buy insulated tools with thick rubber handles to protect you from potential shocks.
Screwdrivers of multiple sizes can be helpful for tightening the screw connectors in your main service panel or inside a plug.
It also helps to have multiple types of pliers.
Flat headed ones can be useful for reaching and grasping objects, as well as crimping the end of wires to provide a better connection.
Sharp pliers will be necessary for cutting wires into the correct lengths you need.
It also helps to have a wire stripper, although you don’t need one. You can just as easily strip the plastic sheathing off a wire with a pair of sharp pliers or a set of scissors.
That said, having dedicated wire strippers could make your work much faster and will prevent you chopping through the whole wire by accident.
You will also need a multimeter to check the status of your appliances and circuits. There are many different models available, all with varying features.
With a good multimeter, you can measure the voltage passing through a circuit as well as the current and resistance.
All of these will be useful measurements when working with electronics, especially if you are trying to diagnose a problem with a faulty circuit.
A Wall Chaser And Drill
These are only necessary if you want to add a new circuit to your home and need to hide wires behind your walls.
A wall chaser is a power tool that electricians use to cut thin groves in a wall so that they can insert conduits or cables behind them.
If you are doing this kind of work then a wall chaser will be very useful along with a good cordless drill.
This will help with making small holes in your walls for feeding wires through.
This is another useful piece of kit for anyone who wants to install new wires behind their walls.
These are long, thin rods that can be used to pull a length of wire through a conduit or other enclosed space.
Without them, you could spend ages trying to grab the end of your wire with pliers or your fingers.
Electricians’ snakes make this job much easier and are worth buying just because of the amount of time they will save you when laying wires.
If you are working in any area with low light, then you will need a head torch. Handling electrical circuits is already dangerous enough when you can clearly see what you are doing.
Playing with wires in the dark is a recipe for disaster, which is why you need a head torch for a convenient, hands-free source of light while you work.
Color Code For Residential Wires
If you look inside the main power cable for any appliance in your home, or open up one of the conduits in your walls, you will see a large array of differently colored wires.
With so many different colors, it can get pretty confusing which one does what.
Knowing what the different colors of wire represent and mean is essential if you want to do any work on the electronics in your home.
Not knowing which wire is live and which is neutral could easily lead to some unfortunate mistakes.
The problem is that only a few of the colors are consistently used for the same applications.
Other colors may have more than one use, so it is important to know which ones these are, so you can trace them back to the source and work out what they are.
Hot wires are the main current carrying wire in any circuit and are responsible for carrying a voltage to any appliance that needs powering.
Circuits carrying 120V power will often only need one hot wire, while those carrying 240V will need two or even three for some devices.
The most common colors you will see used for hot wires are red and black. Black is the most common, with red being used for 240V circuits that require a second hot wire.
Blue and Yellow wires are quite rare to encounter, but most of the time when you see them they will be functioning as hot wires, although it is best to double-check before doing anything with them.
If you see any white or gray wires that have black or red tape around them, then these are most likely hot wires as well.
Electricians will often use black and red electrical tape to mark white wires that aren’t being used for neutral.
Most of the time, neutral wires will be white or gray, unless their ends have been marked with a piece of black or red electrical tape.
The purpose of the neutral wire is to carry the circuit back to the power source, completing the circuit, so electricity can flow.
For 240V circuits, the second hot wire can complete the circuit itself, so you don’t always need a neutral for these kinds of high-powered appliances.
However, it can be a good idea to hook one up anyway as it gives you spare wire in case something goes wrong.
The ground wire is often colored green, or it may not have a plastic sheathing at all and just be made of bare copper.
The ground wire is an essential part of the circuit, allowing excess power traveling through it to be safely channeled out of the circuit and into the ground through a steel rod at your main service panel.
As such, when short circuits or voltage spikes occur, the ground wire takes this extra power and safely disposes of it to prevent electrical fire of appliances from being damaged.
While some circuits can work without a neutral wire, they all need a ground wire, so if you notice that one isn’t there, you should probably install one as soon as possible.
Ground wire is designed to put up very little resistance to electrical current, so it can do its purpose properly.
As such, you should never use this type of wire for anything other than its intended purpose.
It won’t work as a hot wire, as it may get too hot and damage other wires in your circuit.
Your Main Service Panel
All the branch circuits in your home will route back to your main service panel.
This is the box where mains electricity enters your home, so it can be distributed throughout all the circuits and appliances it contains.
If you are going to be working on any of the circuits in your home, then your first step will be to go to your main service panel and turn that circuit off.
You should never work on live electronics as you will risk giving yourself a nasty shock, or even worse.
In this section, we will cover some of the parts that make up your main service panel. This will help you to know what you are looking at when opening it up.
Busbars are the metal bars in your main service panel that wires and circuit breakers connect to.
The hot bus bars are located in the middle of the service panel and these are the two main terminals that are linked to the main electricity.
These busbars have spaces along them for adding circuit breakers. On the sides of the box, you will see some bare metal busbars that act as the neutral and ground terminals.
These ports are where all the neutral and ground wires connect to.
Circuit breakers are small black boxes that slot into spaces along the hot busbars. All the hot wires from the circuits in your home will connect back to a circuit breaker.
They act as electrical fuses that detect when a voltage spike or short circuit has happened and trip to cut off power to the circuit before it can cause further damage.
Unlike fuses, you don’t need to replace a circuit breaker once it trips, you simply need to address the issue that caused it to trip.
After this, you can go to your main service panel and flip the switch on the breaker to restore power to the circuit.
Circuit breakers are used to apportion power to different circuits, and there are many different sizes and types for controlling different currents and voltages.
You can use them to turn off certain branch circuits in your home, which you will want to do if you are planning to perform maintenance on them.
When adding a new circuit breaker to your main service panel, it is vital that you use the right size of wire for the breaker you have chosen.
We will cover more on how to match the correct gauge of wire to each type of breaker later on in this article.
The Main Breaker
The main service panel is controlled by the main breaker, which is a large circuit breaker that is connected directly to the hot bus bars and the mains electricity that flows through them.
Its purpose is to shut off power to all the circuits in your house if one of them is compromised, to prevent an electrical fire starting in the main service panel.
When you have a power cut in your house, this is the breaker that you have to switch on to restore the power to your home.
The three large wires that supply power to your service panel from the mains electricity will connect to the neutral busbar and the hot busbars by two screw connectors.
Since these screws are connected directly to the mains, they are always hot even when the main circuit breaker has been tripped.
The only way to safely touch these screws is to pull the meter in your home.
However, you shouldn’t attempt this unless you really know what you are doing and if you suspect it may be necessary you should call a professional electrician.
The Grounding Rod
To the side of your main service panel, you will see it is connected to a rod of metal that travels into the ground.
This is the grounding rod, and it is linked to the ground busbar in your main service panel to help it do its job.
Excess power that could damage the circuits in your home travels through the ground wires into this rod, where it is safely channeled into the ground.
These rods are often made out of galvanized steel that has been copper plated to improve its conductivity.
Different Types Of Circuit Breaker
As you can tell, circuit breakers are an essential component of the electronics in your house, dividing the mains power amongst the various circuits in your home.
Not all appliances will draw the same amount of power, so it is very important to choose the right breaker for the right job.
Attaching the wrong breaker to a circuit that is too powerful for it, will simply cause it to trip and may trip out the main breaker on your service panel as well.
In this section, we will cover all the different types of circuit breaker that you can use for adding new circuits to your home.
Single Pole Breakers
These are the smallest size of standard breakers and, as their name suggests, they only have one pole and one connection point for attaching to a single wire.
Surprisingly, these breakers are responsible for controlling most of the plug outlets and lighting fixtures in your home.
Single pole breakers are used for small 120V circuits that are often connected up to 12 different low amp appliances.
Since only one wire is connected to these breakers, the circuits that connect to them need a neutral wire to be completed.
Most single pole breakers can supply between 15 and 20 amps, although some can go as low as ten.
Double Pole Breakers
While single pole breakers are used for branch circuits that connect to multiple different outlets and appliances, double pole breakers will often be linked to a single high-power appliance.
These breakers have two poles and two connection points for attaching wires.
As such, they need two hot wires to link back to them and don’t always require a neutral connection because of this.
These breakers often have a high amperage for supplying power to larger utilities and electronics that need more juice.
Double pole breakers can only be used for 240V circuits and are great for anything that uses a motor such as a washing machine, tumble dryer, or power tools.
These units can supply between 20 and 60 amps, with some even going as high as 100.
A ground-fault circuit interrupter (GFCI) is a special type of breaker that can act much faster to shut down a circuit.
If they detect a fault, these breakers can act to shut down the power to a circuit within 1/40th of a second.
Because they are much faster at interrupting a potential electrical hazard, these breakers are commonly used in circuits that are close to water.
This includes swimming pool pumps, electric kettles, or sockets that are nearby to a tap.
If water does get to the circuit, the GFCI breaker will shut off the power before any serious harm can be done.
GFCI breakers come in both single pole and double pole sizes and are unique in the way that you have to connect them to your main service panel.
All GFCI’s will come with their own neutral wire that you will need to link up to the neutral bus bar.
This is the same for double pole GFCI’s as well, so always remember to save space on your neutral busbar if you plan to install one in your main service panel.
Arc-Fault Circuit Interrupters (AFCIs) are another kind of breaker designed to offer special protection against arc faults.
An arc fault is often caused when the flow of electricity starts to follow an unintended path.
This can be caused by a loose connection, or a wire being broken somewhere in the circuit.
In these cases, an AFCI will act quickly to shut down the circuit and protect the rest of the electronics.
AFCI protection is required in some states on all branch circuits, that is to say any 120V circuit that supplies multiple appliances.
This is to provide protection in case something happens to one branch of the circuit, in which case the whole thing will need to be shut down to prevent a possible electrical fire.
When installing an AFCI you need to connect both the hot and neutral wires to the correct terminals on the breaker itself.
You then need to run the neutral wire attached to the breaker back to the neutral busbar.
AFCI breakers are available as both single pole and double pole units, so you can provide arc fault protection for larger appliances as well as branch circuits.
Tandem Circuit Breakers
These are special circuit breakers that are designed to supply two 120V circuits while only taking up one space in your main service panel.
They are incredibly useful for when you have limited space in your service panel but need to attach more circuits.
You can identify a tandem breaker by looking for a unit that is the same size as a single pole breaker with two levers on the front.
Each lever controls its own circuit, and they will trip individually so that one can operate while the other is turned off.
It should be noted that the use of tandem circuit breakers is restricted in some states.
Before you try to install one, you should consult with an electrical inspector to see if you are allowed to do so and how many you are allowed to have.
You cannot buy AFCI or GFCI tandem breakers, so they cannot be used in any situations that would require this kind of extra protection.
Another limitation of these breakers is that they can only ever provide single phase power, which is inconsistent and not suitable for any item that requires three-phase power instead.
This also means you can’t use tandem breakers to link up two circuits that share the same neutral.
If you want to do this, each hot wire must be connected to a different hot bus bar, necessitating that you use two single pole breakers instead.
Three Phase Breakers
Tandem breakers are the smallest units you can connect to the main service panel, and three-phase breakers are the biggest.
You will rarely find these breakers in any residential home, but if you wanted to supply power to a workshop in your garage that has lots of power tools, then this is the tool you would want for the job.
These circuit breakers have three hot wire connection points for providing three-phase power to large appliances or pieces of heavy machinery.
Three-phase power is much more consistent than single phase, which means that your device will be able to draw all the juice it needs without worrying about electrical fluctuations.
Again, you will rarely need to ever use a three-phase breaker in most residential homes.
If you did want to install one for any reason, you would need to make sure that you can do so without overloading your main service panel.
Since they take up three breaker slots, you may also struggle to find enough space for one of these breakers without installing a dedicated subpanel (see also ‘How To Install A Subpanel/ How To Install Main Lug‘) for whatever they are powering.
Choosing The Right Wire For Each Circuit Breaker
All circuit breakers will have a specific capacity, often measured in amps.
It is important that any appliances you connect to these breakers don’t exceed this capacity, as otherwise they will simply trip and not allow power to flow.
When calculating the number of appliances or outlets you can connect to a breaker, the total number of amps you are putting in should be 20% less than the capacity of the breaker.
So if you had a 100 amp breaker, the total number of amps passing through it shouldn’t be greater than 80.
This is to allow for extra current on high voltage loads and offer a bit of additional protection against voltage spikes.
The higher a breaker’s maximum capacity, the thicker the wire that needs to be connected to it. Wire heats up as it conducts electricity, and this can cause it to expand and contract.
If you run too much current through a very thin piece of wire, then it may melt its plastic sheathing and come into contact with other wires.
This will lead to a tripped breaker at best and a full on electrical fire at worst.
When wiring up a circuit breaker, you should only ever use 600V wire.
Never try to use an extension cord as this is not rated for 600V and could lead to all sorts of problems further down the line. It is also vital to only use solid copper wires.
Aluminum wires will expand and contract more as they get hot, which means they are more likely to lead to a loose connection.
Solid wires are necessary because they provide a better point of contact when inserted into a terminal.
Frayed wires won’t offer as stable of a connection and should never be used for linking to circuit breakers.
Below you will find a list of the different gauges of wire and the number of amps they can typically handle.
- 18 gauge wire – The thinnest gauge of wire should only be used with 120V circuits that connect to 7 amp breakers.
- 16 gauge wire – This wire is for 10 amp breakers on 120V circuits.
- 14 gauge wire – Should be used for 120V circuits that link back to 15 amp breakers.
- 12 gauge wire – Use this for 120V circuits that link back to 20 amp circuit breakers.
- 10 gauge wire – You should use this gauge of wire for 30 amp circuit breakers that power either 120V or 240V circuits.
- 8 gauge wire – Is for 40 amp circuit breakers that will often be used for 240V circuits.
- 6 gauge wire – Should be used for 55 or 60 amp 240V circuits.
- 4 gauge wire – You use this wire for 240V circuits that connect back to 70 amp breakers
- 2 gauge wire – This is the thickest gauge of wire and can be used for 95 amp plus breakers and only for 240V circuits.
If you are laying wires over a distance greater than 100ft, then it will be a good idea to use the next gauge up from what you normally would.
This is to counteract resistance and maintain the same current over the greater distance.
Most of the time you will buy wire in cables, and you should always choose the right cable for connecting back to a specific type of breaker.
All cables will have a ground wire, but will differ on how many hot cables they use.
Wire for 120V circuits will have one hot wire and one neutral, while cables for 240V circuits may have two hot wires and neutral instead.
You can use 120V cables for some 240V circuits, provided it is the correct gauge for handling the greater current.
In these instances, you can often use the neutral wire as your second hot wire, but make sure to mark it with a piece of electrical tape so that future electricians will know what you have done.
For 240V GFCI or AFCI breakers you will need a cable that has ground, neutral and two hot wires since these need to be linked back to the neutral busbar.
Can You Join Two Different Gauges Of Wire Together?
When linking up branch circuits, you may find that you need to link together two different gauges of wire. This is possible, but in order to do so, you will need an inline fuse.
You can join the neutral and ground wires directly together from both cables.
It is recommended to crimp the wires together and wrap the connection point in electrical tape to secure it.
Never use solder for any circuit carrying 120V or 240V loads. The high temperatures generated by these currents will melt the solder and possibly cause an electrical fire.
Connect the hot wires from each cable to both ends of the inline fuse. This means if the voltage gets too much for the thinner wire, it will blow the fuse and protect the circuits.
Never connect an inline fuse to the neutral or ground wires, as you don’t want these to ever be turned off.
Adding A New Circuit To Your Main Service Panel
If you want to expand your main service panel and add a new circuit, then you can likely do so yourself with a few basic tools and materials.
It is vital that you are confident in what you are doing, and take all the necessary precautions to avoid injury.
Remember, if you aren’t sure what you are doing is right, then you should stop and call a professional electrician.
Figure Out What You Want To Power
Before you start work, go to your main service panel and find the breaker that controls the flow of power to the area of the house you are working on.
Switch this breaker to the off position, so you can work without the risk of electrocuting yourself.
Always test any circuit, socket or appliances with your AVI to make sure it is properly dead before you touch or work on it.
The first thing you will want to do is plan out the circuit that you want to add to your main service panel.
This will entail figuring out how many plug sockets you will need, what you plan to plug into them, and any other appliances that you want to connect.
For instance, you might want to run 240V circuit back for running a dishwasher in your kitchen, or you might want to equip a guest house with basic lighting fixtures and plug sockets.
Each will require their own materials, but the first thing you will want to do is check that your main service panel has the space for what you want to do.
This means checking that there is physical space on the hot busbars for attaching the breakers for your new circuit.
You will also need to find out how many amps your main service panel is rated for, and count up the amperage of all the breakers it already contains.
This will allow you to work out how many amps your panel is already handling and how many more it can take without being overloaded.
An easy way to work this out is to look on the inside of the fuse box door.
Here you may find a simple ratio that tells you how many breakers and circuits your service panel is built to handle.
For most homes this will be 20/40 which indicates that you can fit 20 breakers in the box, which should be able to power 40 different circuits.
However, it isn’t always this simple, and you should consult with an electrical inspector, so they can tell you exactly whether your planned circuit is feasible or not.
Once you have worked out that your circuit is possible, make a list of all the things you will need so you can pick them up from the shops.
Install Outlets And Fixtures First
Once you have everything you need, start installing the plug sockets and fixtures that you want your circuit to power.
You will likely need a jig-saw for cutting holes in your wall that plug sockets will fit inside.
You will also need to choose the correct gauge of wire for your specific job. If you are unsure about which gauge of wire to use, consult the previous section in this guide.
Install junction boxes at any points where two different cables meet and join together. This will provide additional protection against the possibility of electrical fires.
Once you have wired up your fixtures and sockets, you will want to feed the wires back to the main service panel.
Do so methodically, thinking about the quickest route you can take and remembering to make use of junction boxes whenever you need to connect two different cables.
When installing any kind of new circuit on the first floor of your home, do so by running the wires along the joists under your floor rather than inside your wall.
Use your wall chaser to make thin grooves in the walls or floors, that you can insert your cable into.
Have an electrician snake handy for pulling cables through tight gaps or crevices where you can’t reach your fingers.
Connect The Wires To The Main Service Panel
Once you have fed the cable back to your main service panel, switch off the main circuit breaker. Connect the ends of your cable to the breaker before you insert it onto the hot busbar.
Make sure to tighten the screws on the terminals to ensure a firm connection.
Slot your breaker into an available space, if it is a GFCI breaker, then you will need a cable that has a neutral wire for connecting to the appropriate terminal.
You will then need to link the neutral wire attached to the GFCI or AFCI back to the neutral busbar.
You will also need to run a neutral wire back to this busbar when installing a 120V single pole breaker.
Run the ground wire to the ground bus bar and voilà, your new circuit should be installed.
These are just rough instructions that will help those who already know a bit about electronics to do some DIY wiring in their homes.
If you have zero experience working with wires, then please consider calling a professional electrician before you attempt any of the above.
Main voltage is extremely deadly and should never be played with by those who do not know exactly what they are doing.
Hopefully after reading this guide you should know a lot more about what the different colors of wire mean, and the different circuit breakers that they connect back to.
If you ever want to add a new circuit to your home, always make sure to choose the right breaker and the right gauge of wire for the job.
This will not only save a lot of hassle, but it will ensure that everything is safe from potential voltage spikes or unforeseen disasters.
Remember, electronics are no joke, and knowing more about them is the first step to preventing a nasty accident.