If you have been to an electrical store, you will notice electrical wires come in several sizes. Most people would think that the size of the wire does not matter and is pure aesthetics. In reality, its size greatly depends on other things, such as the electrical current passing through the wire. We will be going through the different wire sizes in the following sections using the American wire gauge system. Each section is conveniently named, so you can quickly use your browser’s search function to jump to the section you like.
THHN vs. THWN
When looking at electrical wires, manufacturers use different types of material for the coating. The most common wire types are the Thermoplastic High-Heat Nylon-coated wire (THHN) and the Thermoplastic Heat and Water-resistant Nylon-coated wire (THWN). If you are thinking about how these two are different, the THWN can operate in an environment similar to the THHN without using additional accessories. Although the Thermoplastic Heat and Water-Resistant Nylon-coated wire is a better version of the THHN wire, you can still find both wires across different infrastructures.
Thermoplastic High-Heat Nylon-coated wire (THHN)
The Thermoplastic High-Heat Nylon-coated wire is probably the more common wire between the two. You can find this product in almost any building, whether commercial, industrial, or residential. Depending on the wire’s size, it comes in either a stranded wire or a solid wire. The wire itself uses either aluminum or copper as the conductive material. Finally, polyvinyl chloride (PVC) wraps the conductive material and serves as insulation. THHN rates at 75°C in a wet location or 90°C in a dry location. Several wires of this type carry a dual rating cable, which you can identify by a THHN / THWN marking.
If you are thinking about distinguishing this wire from other wires, you will have to observe its PVC insulation. In most cases, it uses a thinner one, which is important in electrical properties. A negative effect of having a thin insulation layer is frequent leaking of current that can lead to a breakdown. Moreover, when the insulation in a THHN wire burns, it releases toxic smoke, which is highly undesirable in most cases.
Since this type of wire uses nylon coating, it is not extremely flexible. It becomes an issue for some people, especially those who would like to maximize saving time and energy during installation. Despite its cons, the THHN is still very popular because it is a cheaper solution. When you plan to wire an entire building, you will want to save money whenever you can. Having a cost-effective solution without sacrificing safety goes a long way, which is why several people still go for a THHN wire.
Thermoplastic Heat and Water-resistant Nylon-coated wire (THWN)
The Thermoplastic Heat and Water-resistant Nylon-coated wire is the least common between the two. You can mostly find this type of wire in industrial and commercial buildings per the National Electrical Code. Its outer layer is tough yet easy to pull and bend. When installing this wire, electricians will not have a hard time bending the wire, saving them time and energy in the long run. The THWN wire is also resistant to common chemicals, such as flames, gasoline, moisture, and oils.
Unlike THHN, you can commonly find the THWN wire in alternating current electrical distribution systems across the country. You use this wire when installing machine tools, conduit, feeders, and controlled circuits. These systems typically have voltage levels that range from 110 volts to 600 volts. It uses copper or aluminum conductors, which come in either solid or stranded.
It is suitable for use up to 90°C temperature in both dry and wet locations. However, when it comes in contact with oil or coolant, the suitable temperature you can expose it with decreases to 75°C.
The THWN wire has approvals from several laboratories and regulatory boards, such as but not limited to the Canadian Standards Association, Underwriters Laboratories, American Society for Testing and Materials Miscellaneous, and the Restriction of Hazardous Substances.
Standard wire gauge chart
This section only serves as a guide when looking at a wire gauge chart. If you plan to install anything involving electricity, always call for a professional electrician to handle the work for you. It is important to know about the right wire gauge for your needs. Electricians in different regions reference different wire gauge charts, but the one in this section is for the United States.
The easiest and quickest way to determine the size you need is to use a standard wire gauge instrument. In the United States, we use the AWG, otherwise known as the American Wire Gauge system. It defines the diameter of the wire gauge, commonly known as the solid round wires. On the other hand, the ampacity defines the highest current a certain wire gauge can handle.
When looking at the below table, the AWG value is opposite to the wire’s diameter. It means a higher AWG value would mean a smaller wire size. As an example, a 12-gauge wire can carry a higher amp than an 18-gauge wire. To make it easier for you, we defined the diameter in inches and millimeters.
To quickly summarize the chart, the 0000-gauge AWG wire has the largest diameter, whereas the 40-gauge AWG wire has the smallest diameter. A smaller wire diameter lets less energy compared to a larger diameter. For more details on the diameter of each AWG, you may refer to
the chart below.
|AWG||Diameter (inches)||Diameter (millimeters)|
Is it dangerous to use the wrong size?
The short answer to this question is yes, it is dangerous to use an incorrect wire size, the same way you want to avoid unnecessary danger if you’re welding, why you’d wear the right goggles and use the right welding gas. A common misconception for people to think is that as long as the wire fits with the connector, there won’t be any issues. When dealing with circuit breakers, pay much attention to the wire. Those who are unaware often use an AWG wire below the recommended size because it is cheaper, thinking it won’t make any difference. In the long run, getting a smaller wire than what you should be getting will only cost you more.
Professional electricians often recommend using a larger wire for your circuit breaker. In this way, you will greatly reduce the chances of using the incorrect wire, more specifically picking one that can’t handle the necessary amount of amps you’re dealing with. Picking a bigger wire will not have any negative impact on performance or safety. The only negative effect it has is on your budget, which will cost you more than using a substandard wire. However, looking at it in the long run, you can save more because you will unlikely run into damages with your circuit breaker.
How to choose the right size?
When dealing with electrical wires, it is important to know about compatibility across different scenarios. Choosing an incorrect wire size could lead to burning or fire at worst. Several people think that the wire’s size does not play an important role, but it does. Pick the correct wire size to prevent any accidents from happening.
When dealing with a setup involving the circuit breaker, extra precautions need to be in place. For example, the AWG wire needs to be compatible with the circuit breaker you plan to use. A wire that is too small for the circuit breaker could lead to a drop in performance. At worst, it can start a fire.
In the following sections of this article, we will discuss the maximum amps a particular AWG wire can support. For example, if you have an 8-gauge wire, will a 30 amp circuit breaker work with it without any issues?
0 (1/0) gauge
There is a general rule of thumb when choosing an AWG wire that can handle your amp requirements. An AWG wire can handle any amount of amperes below its maximum capacity.
For the 0 (1/0) gauge wire, the maximum amperes it can handle is 150 amps, which means it can handle any amount of amps as long as it is below its maximum capacity. Typically, you can use it as a cable for your car audio.
2/0 copper wire
You can use a 2/0-gauge copper wire for a maximum of 190 amperes. It can handle anything below its maximum capacity without any issues. If you own a sailboat that operates with a battery, you can use this to replace any wire that connects to the battery.
A 3/0-gauge wire supports a maximum amperage capacity of 239 amps and can handle anything below its maximum capacity. A 3/0-gauge wire is perfect to use with a portable solar setup, allowing you to get the most amps.
If you have a 1-gauge wire, it supports a maximum of 119 amps. Any device that needs 119 amps of current or below will work fine with a 1-gauge wire.
A 2-gauge wire supports a maximum capacity of 94 amps, which means it will work just fine for any device that needs less. It is good to use a 2-gauge wire for relocating your car battery. You can also use it to install amplifiers and high-powered car subwoofers in your vehicle.
You can use a 3-gauge wire for a maximum of 75 amps. It can also support any device below 75 amperes. It is good to use this wire in your main panel or subpanel at home. Be sure your electrical system at home has a ground wire, so excess electrical charges have a safe place to travel in case.
A 4-gauge wire, otherwise known as the 4 AWG wire, supports a maximum amperage capacity of 60 amps. This wire has a wide range of applications. You can use it to wire your audio devices, such as a subwoofer or amplifier, off-grid systems, such as a solar panel system, welding applications, and battery.
If you have a 6-gauge wire, it can support a maximum of 37 amperes. It can also support any device that needs less than 37 amps. A 6-gauge wire is good to use with almost anything that involves automotive. If you plan to use this in an automotive, be sure to consider motor vibration. Over time, it could cause the wire to break, so be sure to provide enough isolation and strain relief.
An 8-gauge wire, also referred to as 8 AWG wire, supports a maximum amperage capacity of up to 24 amps. This wire is good to use with batteries, lamps, household appliances, meters, model cars, model planes, and electric heating appliances.
If you have a 9-gauge wire, it can support a maximum of 19 amperes. It is ideal to use this for a 4-channel amplifier to speaker installation.
A 10-gauge wire can support a maximum of 15 amps. This wire size is useful for household appliances, meters, motor, electric heating appliances, and lamps.
If you have a 12-gauge wire, it can support a maximum amperage capacity of 9.3 amps. You can usually use this wire in connecting an amplifier with a subwoofer.
A 14-gauge wire supports a maximum ampacity of 5.9 amps. It also supports anything below 5.9 amps. It is good to use a 14-gauge wire in your car audio system or home theater system.
A 16-gauge wire supports a maximum of 3.7 amperes and can handle any device below it. Typically, you can find this wire size in aluminum batteries, RC batteries, and LED lighting.
You can use an 18-gauge wire with any device that needs 2.3 amperes or less. This wire size supports a wide array of applications, such as at home, school, auditoriums, churches, and schools.
A 20-gauge wire supports a maximum ampacity of 1.5 amps, which means it can handle any device that requires less than 1.5 amps. You can widely use this wire size in RC batteries, model wiring harnesses, motors connecting with other equipment, and LED lighting.
A 22-gauge wire can handle a maximum of 0.92 amps. It is good to use it in RC batteries, aluminum batteries, large transformers, and LED lighting.
If you have a 24-gauge wire, it can handle a maximum of 0.577 amps. You can use this wire size in electrical equipment, LED lighting, aluminum batteries, and RC batteries.
A 26-gauge wire can handle a maximum of 0.361 amps. In most cases, you can use this wire for gate openers. However, be sure to check the current requirements before getting one. You can also use a 26-gauge wire in your solar panel system.
A 28-gauge wire can handle a maximum ampacity of 0.226 amps, which means it can handle any device that has a smaller amps requirement. This wire size is good to use with aluminum batteries and LED lighting at home.