THHN wire size & amp chart

Any new electrical wiring work must be done carefully, whether in the home or workplace. Suppose you are not familiar with electrical gauges and amp ratings. This article will ease you into the learning process.

Soon you’ll be checking your electrician’s work like a pro. Keep reading to find all the tips to ensure the safest and best 2 through 20 gauge wire & amp rating.


The best way to find the gauge wire amp rating is by using the AWG wire size chart below. From it, you’ll discover the following.

  • The amp rating for 2 gauge wire is 90 amps at 167°F ambient temperature using copper.
background fore gauge wire article

Table of Contents

Why you can trust us and how we picked?

You can trust us as we have worked closely with industry experts to test out different gauge wires. We have measured the output based on two factors i.e. Thickness and length. The products which withstood our standard checklist are presented below.

THHN wire size chart

You no longer need calculators, resources, or tables scattered around the internet. Here is the THHN wire size chart you need. You’ll easily see the values and load the different options can handle, including ambient temperatures. Fining out ampacities is no longer hard for your power cable!

Wire Gauge Size90°C (194°F)
75°C (167°F)
60°C (140°F)
90°C (194°F)
75°C (167°F)

What are different sizes used for?

circuit breaker

Let’s look at the most common options used in the industry and what they are used for.

2 gauge

A 2 AWG copper wire is commonly used for Central electrical heating systems. Its diameter is approximately 0.2576.” This size is ideal for installing circuits where high flame retardation is required.

A 2 gauge copper insulated wire can carry the rated amperage is 95A at 60degree. While at 75 degrees, it can carry 115A. This cable is rated 75 A at 60 degrees and 90 A in the aluminum form at 75 degrees. Celsius refers to the temperature rating of the conductors.


If you need a 2 gauge wire, here’s our recommendation.


  • It’s made in the US.
  • You get copper as the material used.
  • A trusted seller.


  • The wires are only 25′ long.
TEMCo Industrial
It's made in the US.

4 Gauge

At a 60 degrees Celcius rating, a copper conductor of this size is rated at 70 A. At the same time, it is rated 85 A and 95 A for 75 degrees and 90 degrees.

The 4 AWG size is generally sized at 0.2043 inches in diameter. Like the 2 AWG type above, it is generally used in large heating systems and electric furnaces. Fire safety is a major concern.

Number of Cable StrandsMulti Strand
Number of units2
Temperature Range‎-50°C to +105°C Degrees Celsius


  • We’ve always been happy with the shipments we have received from this seller.
  • We received what we were supposed to.
  • The price was very reasonable.


  • We couldn’t see any markings on the wire received.
  • Some people say they received less than they were supposed to.
  • The shipping could be faster.
TEMCo Industrial
Here's a thinner one.

6 Gauge

The 6 AWG size is approximately 0.1620 inches in diameter. It is rated for 55A at a temperature rating of 60 degrees. While at 75 degrees and 90 degrees, it is rated at 65 A and 75 A.

While in aluminum types, the amp rating is 40 A and 50 A for 60 and 75 degrees Celsius. It is generally used in electrical cooking ranges and cooktops. It can also be used in heat pumps and wiring of on-demand electrical water heaters.

8 Gauge

The 8 AWG is sized at 0.129 inches in diameter. The copper conductor form is rated 40A at 60 degrees Celcius and 50 A at 75 degrees Celcius.

While at 90 degrees celsius, the ampacity is approximately 55 A. The ampacity is 30 A at 60 degrees in the aluminum form and 40A at 75 degrees.

This type has several names and is known as:

  • hook-up wire
  • hot tub wire
  • conduit wire
  • construction cable
  • and lighting wire.

It is usually covered in a nylon sheath, Thermoplastic high heat resistant nylon (THHN). This size is generally used for indoor projects. The nylon jacket protects against damage and shock and prevents the metal conductor from receiving any abrasion.

A common use is carrying current to and from indoor light switches and appliances in homes and offices. It is why this product also goes by “building wire.”

10 Gauge

10 AWG is sized at approximately 0.102 inches in diameter. In copper form, the ampacity at 60 degrees celsius is 30 A and 35 A at 75 degrees celsius. While at 90 degrees Celsius, the ampacity is 40 A. The ampacity remains a fixed 25 A in the aluminum form at 60 degrees and 75 degrees Celcius.

Some common uses of a 10 AWG wire are in the electrical clothes dryer and electric water heaters rated 30A. It can also be found in 240V window air conditioners.

This wire is bare copper in non-insulated form and can also be used for grounding and bonding purposes. This process is connected to a grounding rod. It redirects any extra current to the ground in case of fluctuations.

12 Gauge

A 12 AWG has a size of 0.0808 inches in diameter. It is rated at an ampacity of 20A at 60 degrees and 25A at 75 degrees. At 90 degrees Celsius, it’s rated at 30A.

While in aluminum 12AWG, only an ampacity of 15A is supported at any given temperature rating. This type can be found in kitchen and bathroom projects. Apart from this, it can also be used in an air conditioner of 120V.

For outlets and lights, it’s the best option on a 15A or 20A circuit. Even though they might cost you more than a 14AWG size, they’re better. It is also commonly found in refrigerators in 12-2 Romex form.

14 Gauge

A 14 AWG wire is 0.0641 inches in diameter and is commonly found in lighting circuits due to its high flexibility and very thin size. For a visual, it has roughly the same thickness as a dime.

It is rated for 20A and 25A at 60 degrees Celcius and 75 degrees celsius. Most electricians prefer a combination of 12AWG and 14AWG in light fixtures and lighting circuits. Moreover, there has been a recent shift in demand from 14AWG to a 12AWG wire in residential projects.

This is due to a limit of 8.4 receptacles on a 14AWG circuit and a 10 receptacle limit on a 12 AWG circuit. A 12AWG has less resistance than a 14AWG one which means less energy is wasted, and an eco-friendly circuit is created.

Incorrect wire size and amp rating causing burning wire

16 Gauge

This unique size is rated for 18A at 90 degrees Celsius and is 0.0508 inches in diameter. It can be found in extension cords of light-duty. It is commonly found in lamp cords and supplies current from portable devices to current sources through wall sockets and other areas.

It is also used in repair work for clocks and floor lamps. It’s great for low-energy appliances. Stranded and TFFN-sheathed forms can also become part of fixture wiring. Automotive purposes like trucks and RVs feature 16AWG stranded wiring that is oil and flame resistant. Overall, a 16 AWG wire is very versatile.

18 Gauge

A standard 18AWG wire comes in 0.0403 inches in diameter. 18 gauge wire is rated for 10 amps at 60 degrees Celsius. It’s rated 14A at 75 degrees and 16A at 90 degrees celsius. It is generally part of lamp cords of 10 amps and low-voltage lighting.

Just like 16AWG, it can also be used in automotive functions. It can be bought for portable wiring when a rubber jacket covering is installed outside. It makes it weather and oil-resistant.

This rubber is known as a thermoplastic elastomer or TPE jacket. 18 AWG can also be used for HVAC equipment and control panels. It’s great due to its high flexibility.

20 Gauge

20 AWG is measured at 0.0320 inches in diameter and is rated at 5A and 11A at 60 degrees and 75 degrees Celsius. This type of hook-up wire is mostly found within control panels and computers.

It can also be found in meters and ovens in solid and stranded forms. It is found as flex control cables in innovations like a robotic arm or other automated machinery where moving components are present.

It has the flexibility of a 20AWG cable and allows for rapid movement and flowing current to operate without any obstruction.

The 20AWG wire can be used as a coaxial cable in video applications and digital devices that need audio synchronization in bare copper braid form. This includes cable TV and LAN connections.

22 gauge

A 22 AWG wire is sized at 0.0253 inches in diameter. It is rated for 3A and 7A at 60 degrees and 75 degrees Celsius. This type is so thin and fragile that it is usually part of analog device prototyping and breadboarding projects.

22AWG cable is used as communication cable connectors for fire alarm systems and networks in stranded form. You can find it in computer cables and other security-related cables.

24 Gauge

A 24AWG wire is sized at 0.0201 inches in diameter. It features an ampacity of 2.1A and 3.5A at 60 degrees and 75 degrees Celsius.

LAN cables use this to transport data that includes both audio and visual transmissions. It is highly sensitive to temperature. It is used for thermocouple wires that sense the temperature of an object and feed it to other monitoring devices.

What is a gauge, and what are its types?

red wire on the ground

The gauge of a wire refers to its diameter and hence its current carrying capacity.

Different parts of the world use different standards for measurement. Here are the most popular types:

  • IEC 60228: This is the standard set by the International Electrotechnical Commission on international conductors of cables. It is the wire-size measurement standard used in most parts of the world.
  • AWG: American Wire Gauge is another standardization system in use since 1857 in North America. Today, this system is widely adopted in the United States and Canada. Like many other non-metric systems, the increasing number of AWG automatically denotes a decreasing diameter. This is similar to the British Standard Wire Gauge system. Apart from electrical wires, it is also used to denote the sizes of body piercing jewelry.
  • SWG: Standard Wire Gauge refers to the unit used to measure the thickness given by British Standards in 1964. Although originally widely adopted, it is in use in very small areas now. Today, it is only known to be used to measure guitar strings and some cables.

How to install a breaker?

A circuit breaker is essential in every home’s main control panel for adequate electrical fire safety. Each time an overload or fluctuation causes a current to overflow, the circuit breaker breaks off all contact points.

It shuts down the circuit to prevent wires from shorting and causing a fire or blast. This makes it an essential part of every circuit. Its maintenance and servicing must be taken seriously.

breaker being installed

Before you begin

Before you start your project of replacing a circuit breaker, you need to know the right type and brand of the breaker you’ll be installing.

electrician installing 30, 40, 50, 60, 100, 200 amp wire

A label near the reset button of the circuit breaker’s lever will indicate the exact requirement of the breaker you need. When you have bought this, you will also need adequate lighting or a flashlight and safety goggles. Get screwdrivers of different sizes before you get going.

The Process

Here’s the full detailed guideline for replacing a breaker. Follow professional guidance if you require any additional help or have any queries regarding the installation.

  1. Shut down the main power. This is a must whenever any electrical work is being done. Even if you feel all appliances and lights are off, residual current can cause shocks and accidents. Turning off the main power in the main circuit breaker lever assures no residual current is leftover in the circuit. Carry a flashlight and plenty of batteries to continue the rest of your work.
  2. Take away the cover plate. The breaker panel has a cover that must be removed using the screwdrivers. The corner screws should be removed first and the middle ones last. Be careful never to tip the plate inside the panel while you are removing it.
  3. Deinstall the faulty breaker. Flip the breaker’s level to OFF. You will find a thick insulated black wire connected to the breaker wrapped closely to it. This must be extracted out from the panel while being careful not to touch anything else. Grasp the old faulty breaker and pull it out from the edge using a pivot motion towards the outside of the panel. With a snap sound, the breaker will break free of the panel.
  4. Remove the wires. Now pay attention to the black wire attached to the circuit and unscrew the terminal holding the wire. In a GFCI and AFCI circuit breaker, you will also have to loosen the neutral connection and a white wire running from the neutral bus bar.
  5. Reconnect it to the new breaker. Firstly, make sure to set the lever to ‘off’ on the new breaker. Take the black circuit wire and attach it to the new circuit breaker. Put the bare end under the screw terminal on the breaker. You can identify this terminal through the label ‘neutral’ or ‘load neutral’ on the breaker. The white one must also be attached to the neutral bus bar panel.
  6. Insert the new breaker into position. Now insert the new breaker into the empty location. You should hear the snap as it sits tight on the bus bar. Now wrap the excess neatly around the breaker as you found them.
  7. Put the panel cover back on. Use screwdrivers to screw the middle and corner screws of the plate into position.
  8. Turn on the power. Turn off all individual breakers before turning on the main breaker. After turning the main breaker on, flip the switch on individual breakers to ‘on’ one by one. It ensures that the power demand doesn’t shoot up instantaneously.

Lastly, it’s good to test all your appliances and lighting fixtures to make sure the new breaker is operating properly.

Electrical Safety Tips

red wire

Here are a few tips to always remember around the house and office when dealing with electrical appliances and wiring.

  1. Always make sure the main power is completely off before beginning any work on the circuit.
  2. Only ever buy and use equipment with handles made of non-conducting material when you are working on electrical panels.
  3. Never wear metallic watches and jewelry when working on an electrical panel or appliances.
  4. Wear insulated materials like rubber gloves, safety goggles, and cotton-tight clothes when working with electricity. It’s especially important if engaging in welding work. Also, make sure your hands are dry, and no sign of moisture is near when you begin rewiring.
  5. If possible, work with only one hand throughout the electrical process. This can be done if one hand is kept in your pocket or holding important equipment like a flashlight on the side. Working with one hand reduces the chances of any electrical shock running through your entire body and especially the chest cavity. It reduces the chances of major electrocution accidents.
  6. Any equipment causing even the slightest sensation of electrical shock on touch should be reported for repair immediately.
  7. If any water or liquid spills onto live working equipment, do not try to wipe it off. First, disconnect the equipment from the power source instead and wait for the residual current to pass off.
  8. Never store highly flammable liquids and products near electrical equipment. Gasoline and deodorant bottles should be kept well away from electrical appliances. Anything flammable needs to stay away, especially those with higher chances of flame ignition like a heater.
  9. Never wear loose clothing while working with electricity.
  10. If any circuit panel work or appliance repair is to be left open and unattended, make sure it is powered off. Place a sign indicating ‘repair’ work and ‘caution.’
  11. Keep appliances and devices away from wet areas like the bathroom and kitchen. If you must use them, use them only with a GFCI outlet.
  12. Always keep track of the number of devices and lighting fixtures on a circuit and never overload it.
  13. Use diagonal cutters instead of pocket knives to ensure a cleaner cut on the cable.
  14. When using an extension cord, make sure the amperage rating matches your attached devices.
  15. Never run cables from under carpets and other cloth to prevent chances of fire.
  16. Never tug on a cable of the device to unplug from the socket. Always grab the plug and pull to keep the chances of fraying and damaged cords, which can later be a hazard.
  17. Only use the recommended wattage in light fixtures and lamps.
  18. Never turn on the individual breakers all at once after repair work is finished. Turn them on by one to avoid sudden power demand from the main breaker, leading to overloads and blasts.
  19. Whenever any extension cord or plug feels warm or hot to touch, stop using the device and get it checked before using it next.
  20. Always call a professional whenever unsure about electrical equipment or panels. A licensed electrician must be on call until you turn expert on electrical work.
wire on the floor

We’re sure our article must have helped you on the way to becoming a responsible homeowner. Follow our handy safety tips and detailed instruction guide on installing a breaker. Show off your skills to your guests and friends!

Factors to consider

There are thousands of types and different thicknesses and materials for laymen to buy and install in their homes. To install the correct size, you must consider mainly two things – thickness and length.


The thickness is measured, while the amount of current the wire should ideally carry is measured through amps or amperage ratings. Both of these factors are directly related to each other. The thicker it is, the more current it can carry.


Keep in mind that an increased length can cause the current carrying capacity to drop. To tackle this, you can increase the thickness or gauge to make up for any loss through the heat.


We will be happy to hear your thoughts

Leave a reply

Passion Plans
Login/Register access is temporary disabled