70, 80, 100, 125, 150, 200, 400, 600 Amp Wire Size Guide & Chart

Knowing which wire size to pick is important, so you can use the right one for your equipment that requires electricity. In case this is your first time reading about the topic, we are covering some of the basic things to know about it. 

In a hurry? Buying recommendations

If you’re wanting to buy a circuit breaker, a sub panel, service wire, a transfer switch, a meter socket or a fuse for either your 70, 80, 100, 125, 150, 200, 400 or 600 amp service, we’ve found all the products we recommend. We’re sure our work will save you both time and money!

For those that already know what a gauge is, and the importance of finding the right product depending on what it is going to be used for, we’ll just right into it and share a wire ampacity rating chart where you can figure out yourself what it is that you need. Simply scroll down a little bit. Also, this article was made due to the increasing popularity of our original article. Whether you’re doing gasless MIG welding, welding aluminum or anything else, choosing the right one is crucial.

If you’re looking for a chart that can show you the right wire size for 70, 80, 100, 125, 150, 200, 300, 400 or 600 amp of service, simply scroll down the page a little bit further.

Table of content

A Rule of Thumb

While we encourage you to check out the chart below to find the right products for your project, there are general rules of thumb that techs go by, which we have included in the chart as well. 

For a 70 amp, the safest wire size is a gauge 3. For 80 amp service, the safest wire size is gauge 2. The right wire size for 100 amp service is gauge 1. 125 amp requires a wire size 2/0. For 150 amp, the right wire size is 3/0. For 200 amp service, you will need a wire size 250 kcmil. For 300 amp, the right wire size is 500 kcmil. 400 amp service requires a wire size of 1,000 kcmil. For 600 amp service, we recommend a wire size of 1,750 kcmil.

We’ve got the size chart you need, that easily lets you see the electrical cable requirements for both aluminum or copper.

Below is a table based on conductor temperatures of 140°F unless otherwise stated, taken from the NEC 310.16.

Ground wire, service entrance, circuit, breaker size chart rating
Service or Feeder Rating (amp) Aluminum conductor Copper conductor
70 #2 AWG #4 AWG
80 #1 AWG #3 AWG
100 #1/0 AWG #1 AWG
125 #3/0 AWG #1/0 AWG
150 #4/0 AWG #3/0 AWG
200 350 kcmil 250 kcmil
300 700 kcmil 500 kcmil
400 1,250 kcmil 750 kcmil
600 2,000 kcmil (194°F) 1,500 kcmil (167°F)

Amp amounts

If you are unsure of which type of material you are dealing with, or you don’t know the right temperature, we always suggest erring on the side of caution, why the column to the right shows you the lowest number in the different columns. It’s always better to choose a bigger diameter if you are unsure about any of the conditions that could influence the performance.

circuit breaker

60 amp

As you can see for 60 amp, you will really want a 6 gauge wire size, and if you’re more cautious, a 4 gauge. That is, of course, assuming the right conditions such as temperature.

Let’s say you have an 8-gauge and a 10-gauge lying around at home, and you want to know if you can use these with a 60 amps circuit breaker. The 8-gauge, nor the 10-gauge can handle a 60 amp circuit breaker. Simply check out the chart further down the page.

70 amp

For 70 amp, the right wire size is either a gauge 3 aluminum or a gauge 4 copper, assuming there aren’t other factors impacting the performance.

The requirement depends on whether it is aluminum or copper and the ambient temperature, as you can see from the chart further down. For a 70 amps circuit breaker, you can use 4-gauge copper at an ambient temperature of 140°F.

80 amp

If you’re working with 80 amp electricity, you need a gauge 4 copper wire, whereas it would need to be a size 2 if you are going for aluminum instead. Be sure you get the right one for your subpanel and breaker!

100 amp

The rule of thumb for 100 amp service is that you go with a wire size gauge 1. However, that is only if you don’t consider the material. We’ll go into a little bit more detail below. 

For this amount of service, you need to either get a gauge 1 wire made of aluminum, whereas a gauge 3 will work if it is made of copper, which applies to a breaker & subpanel as well. These recommendations are based on conductor temperature ratings of 167°F. Press this link to scroll to the chart below. It is important that you scroll further down the site so that you’ll come across the table that shows the right recommendations as the temperature will affect the right choice for your sub panel, entrance cable and other electrical components.

Check out the table right below to see the various products we recommend for 100 amp when it comes to sub panels, entrance cable, service wire & more.

Name
Best breaker
T Tocas
Best sub panel
Square D
Best service wire
WindyNation
Best transfer switch
Xantrex 81-2010-12
Picture
T Tocas 100 Amp Circuit Breaker with Manual Reset, 12V- 48VDC, Waterproof (100A)
Square D by Schneider Electric DU323 100-Amp 240-Volt 3-Pole Non-Fusible Indoor General Duty Safety Switch, Steel,Small
1/0 Gauge 1/0 AWG Red 10 Feet Welding Battery Pure Copper Flexible Cable + 10pcs of 3/8" Tinned Copper Cable Lug Terminal Connectors + 3 Feet Black Heat Shrink Tubing
Xantrex 81-2010-12 Inv/Chgr, Free-458 2000W 12V 100A M-Sine
Prime status
-
-
Best breaker
Name
T Tocas
Picture
T Tocas 100 Amp Circuit Breaker with Manual Reset, 12V- 48VDC, Waterproof (100A)
Prime status
-
Best sub panel
Name
Square D
Picture
Square D by Schneider Electric DU323 100-Amp 240-Volt 3-Pole Non-Fusible Indoor General Duty Safety Switch, Steel,Small
Prime status
-
Best service wire
Name
WindyNation
Picture
1/0 Gauge 1/0 AWG Red 10 Feet Welding Battery Pure Copper Flexible Cable + 10pcs of 3/8" Tinned Copper Cable Lug Terminal Connectors + 3 Feet Black Heat Shrink Tubing
Prime status
Best transfer switch
Name
Xantrex 81-2010-12
Picture
Xantrex 81-2010-12 Inv/Chgr, Free-458 2000W 12V 100A M-Sine
Prime status

125 amp

To be on the safe side, you will need to make sure you’re either using gauge 1 copper or a 2/0 aluminum wire size for 125 amp of service. Press this link to scroll to the chart below, or check out the table right below this to see the sub panel and breaker that we recommend.

Product
Best wire
Wire
Best breaker box
Breaker box
B01F76VJ3I
Breaker
2/0 Gauge 2/0 AWG 25 Feet Black Welding Battery Pure Copper Flexible Cable + 10pcs of 3/8" Tinned Copper Cable Lug Terminal Connectors + 3 Feet Black Heat Shrink Tubing
Square D by Schneider Electric DU324 200-Amp 240-Volt 3-Pole Non-Fusible Indoor General Duty Safety Switch,
T Tocas 150 Amp Circuit Breaker with Manual Reset, 12V- 48VDC, Waterproof (150A)
Best wire
Product
Wire
2/0 Gauge 2/0 AWG 25 Feet Black Welding Battery Pure Copper Flexible Cable + 10pcs of 3/8" Tinned Copper Cable Lug Terminal Connectors + 3 Feet Black Heat Shrink Tubing
Best breaker box
Product
Breaker box
Square D by Schneider Electric DU324 200-Amp 240-Volt 3-Pole Non-Fusible Indoor General Duty Safety Switch,
B01F76VJ3I
Product
Breaker
T Tocas 150 Amp Circuit Breaker with Manual Reset, 12V- 48VDC, Waterproof (150A)

150 amp

For 150 amp, as per the chart below, you’re need a 3/0 wire size made of aluminum, whereas a 1/0 is the smallest size you can go with when looking at copper.

Suppose you have a 150 amps circuit breaker at home, and you would like to make use of it. 

In this case, you will need 1/0-gauge copper at an ambient temperature of 167°F or 2/0-gauge aluminum at an ambient temperature of 194°F.

200 amp

200 amp service requires a wire size 250 made of aluminum or a 3/0 size when made of copper according to the chart. Check out the table right below to see the sub panel, breakers, service wire and more that we recommend for this level of service.

Name
Best breaker
T Tocas
Best sub panel
Siemens W0202MB1200CU
Best wire
Best wire
Best transfer switch
Siemens DTGNF224NR
Picture
T Tocas 200 Amp Circuit Breaker with Manual Reset High Amp Switchable, Waterproof, Flush-Mount Circuit Breaker 200A
Siemens W0202MB1200CU 200 Amp Outdoor Circuit Breaker Enclosure
750' 4/0 XHHW Aluminum Cable Wire 600 V Building XLPE 200 Amp USE
Siemens DTGNF224NR 200-Amp, 2 Pole, 240-volt, 3 Wire, General Duty, Double Throw, Type 3R
Prime status
-
-
-
Best breaker
Name
T Tocas
Picture
T Tocas 200 Amp Circuit Breaker with Manual Reset High Amp Switchable, Waterproof, Flush-Mount Circuit Breaker 200A
Prime status
Best sub panel
Name
Siemens W0202MB1200CU
Picture
Siemens W0202MB1200CU 200 Amp Outdoor Circuit Breaker Enclosure
Prime status
-
Best wire
Name
Best wire
Picture
750' 4/0 XHHW Aluminum Cable Wire 600 V Building XLPE 200 Amp USE
Prime status
-
Best transfer switch
Name
Siemens DTGNF224NR
Picture
Siemens DTGNF224NR 200-Amp, 2 Pole, 240-volt, 3 Wire, General Duty, Double Throw, Type 3R
Prime status
-

300 amp

For 300 amp service, you will want copper wire of size 500 kcmil to be able to handle the load.

400 amp

400 amp service requires an aluminum wire size of 1000 kcmil, whereas a 600 kcmil copper size can handle that amount of power – check out the NEC electrical cable chart below.

600 amp

The appropriate wire size for 600 amp service is at least 1500 kcmil assuming a temperature of 167°F of the conductor.

Full wire size chart for 70, 80, 100, 125, 150, 200, 300, 400, 600 amp & more

  Max amp for Aluminum Max amp for Copper   Our recommendation
Wire Gauge Size 167°F 194°F 140°F 167°F 194°F  
14 20 20 25 20
12 20 25 25 25 30 20
10 30 35 30 35 40 30
8 40 45 40 50 55 40
6 50 60 55 65 75 50
4 65 75 70 85 95 65
3 75 85 85 100 110 75
2 90 100 95 115 130 90
1 100 115 110 130 145 100
1/0 120 135 125 150 170 120
2/0 135 150 145 175 195 135
3/0 155 175 165 200 225 155
4/0 180 205 195 230 260 180
250 205 230 215 255 290 205
300 230 255 240 285 320 230
350 250 280 260 310 350 250
500 310 350 320 380 430 310
600 340 385 355 420 475 340
750 385 435 400 475 535 385
1000 445 500 455 545 615 445
1250 485 545 545 590 665 405
1500 520 585 585 625 705 435
1750 545 615 615 650 735 455
2000 560 630 630 665 750 470

What is a gauge?

The gauge is the size of the diameter, basically. This determines how much electrical current it can safely carry. If you have ever been to the electrical section of a hardware store, you will notice it come in several options.

Instead of referring to it using its actual thickness, people would refer to it using its gauge size, 6, 4, 3, 2, 1, 1/0 , 2/0, 3/0, and 750 gauge wire.

It is inversely proportional to the diameter, which means the higher the number, the smaller the diameter. If it is not written on the product itself or is unclear, you can use a thickness gauge to determine it. Getting the right diameter is important because it determines the maximum current it can safely handle. Using an incorrect one could lead to serious problems in the long run. So before deciding which to buy, first check how much electrical current it will handle by identifying the devices you plan to use.

The United States, along with 65 other countries, use the American wire gauge as the unit of measure. Other countries use the Imperial Standard, which was defined by the British Board of Trade.

Make sure to check out two of our other resources as well on Thermo King alarm codes and an in-depth look at welding gas or welding glasses.

Choosing the right one

They usually burns if you use the incorrect one. It is advisable to know the correct one to prevent this from happening. The bad thing is that most people are not aware that your choice makes a difference. People often make the connections themselves without consulting or calling a licensed electrician. It could lead to serious issues when done incorrectly.

When the setup involves the circuit breaker, you should take extra precautions. Installing the right components will greatly prevent common issues from happening. In most cases, issues arise because of an incorrect one. The gauge and breaker need to be compatible with each other.

If you have a 60 amp circuit breaker for your water heater, clothes dryer, or air conditioner that you have no idea which gauge you need, read through the next section as we guide you in understanding the basics. 

What happens when you choose the wrong one

It is a common misconception for people to think that as long as the ends of the wire fit a connector, there will be no issues. It is not the case for circuit breakers. People who are unaware of their importance often use too small gauges to connect their circuit breakers. Smaller diameter ones are cheaper than the bigger ones, which is why people who are unaware often go for the cheaper one, thinking it is not going to make any difference. Sadly, it is only going to cost them more in the long run.

Using a larger one for your circuit breaker is often the best way to go. The only negative effect this has is on your budget, which will cost you more upfront. When picking a larger one, you end up spending more than what you may need. However, it is not going to cause any damage to your circuit breaker. Instead, it can better handle the electrical current flowing through it.

But if you find yourself having the incorrect one, here are the things that might happen.

Consequences
Drop in performance Melted insulation
Fire Damaged equipment

A drop in performance

If you connected appliances to a circuit breaker using one that is too small, achieving peak efficiency may be impossible. The appliances can only receive a part of the energy it requires to operate at peak performance. In effect, your appliances will be unlikely to achieve their optimal performance.

For example, you have a 15 amp circuit breaker, which you need to use for light fixtures at home. Using a service wire that is less than the recommended 14-gauge could lead to performance issues. For electric furnaces, you need at least a 4-gauge. 

Whether you are doing welding in order to combine metal with those precision joints, or you’re powering a metal lathe, make sure to see what the requirement are for that piece of equipment, as you might simply be using the wrong cord, why you’re not getting the performance you were looking for.

It can start a fire

Incorrect wire size and amp rating causing burning wire

A burning electrical component that leads to starting a fire is the worst case. Although modern circuit breakers have their safety measures, it may not be enough if the load is too much.

For example, a common safety measure for modern circuit breakers is the trip mechanism. When the circuit breaker experiences an overload, it will trip to cut the current from passing through, preventing any damage from happening. However, having a trip mechanism does not prevent a fire from happening.

Melted insulation

A smaller diameter can handle less current, which makes them more resistant to the flow of energy. However, if the gauge is way smaller for your circuit breaker, the current flowing through the wire is more than what it can handle. Due to high resistance, heat generates and will eventually lead to the melting. 

Damage to the equipment

Aside from performance drop issues and the possibility of starting a fire, using a smaller one may damage your equipment in the long run. When the supply of power is not stable, it may bust your equipment.

Diameters

Before proceeding with this section, you should know that it is important to have a licensed electrician handle any electrical work. However, it helps to know some of the basic electrical things, such as the right gauge. The chart electricians use as their reference will differ depending on the region. 

Using a standard gauge instrument is a quick and easy way to know the size. We use the American Wire Gauge system, commonly referred to as AWG, in the United States to determine it. The AWG defines the diameter of solid round wires, which is otherwise known as the gauge. The capacity, commonly known as the ampacity, is the highest current it can handle.

When referring to the table below, note that the AWG value is opposite to the diameter. A higher AWG refers to a smaller diameter, which means an 8-gauge can support a higher capacity than a 10-gauge. The chart below defines the diameter in inches and millimeters. The chart should help determine which one to choose.

From the table, the one with the largest diameter is the 0000-gauge, while the smallest is the 40. The former lets more energy flow through it at any given time than the smaller ones will.

Standard wire gauge chart

 

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

 

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