Knowing which size to pick is important, so you can use the right one for your equipment that requires electricity. If this is your first time reading about the topic, we cover some basic things to know about it.
Summary: Buying recommendations
What electrical components do I need for a project? The rule of thumb that techs will usually go by is that for a 70 amp circuit breaker, 4-gauge copper wire is the right size to go with. For an 80 amp, you need a 4-gauge copper wire size. For a 100 amp service, you will need a 1-gauge wire size.
For 125 amps, you will need a 1-gauge copper wire size. For 150 amp, you will need a 1/0-size copper wire size. For a 200 amp service, you will need a 250 kcmil-gauge copper wire size. For a 400 amp service, you will need a 600 kcmil-gauge copper wire size. For 600 amp, you will need a 1500 kcmil-gauge wire size.
We’ve got you covered if you want to buy a circuit breaker or a sub-panel. Here are all the products we recommend based on NEC’s ampacity chart to ensure safety.
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Table of Contents
125 amp
The right wire size for 125 amp service is a gauge 1 copper or a 2/0 aluminum to be on the safe side. Look at the table below to see the sub panel and breaker we recommend for 125 amps of service.
| Name | 1/0 AWG |
| Company | WindyNation |
| Feature | Flexible Cable |
| Item Weight | 9.94 pounds |
| Length | 25′ – 100′ |
Pros
- It does what it’s supposed to.
- Delivery was smooth.
Cons
- 1/0 AWG is expensive.
- The shown product is only 25′.
- The chosen product surprisingly had no reviews at the time we bought it.
150 amp
For 150 amp, you need a 3/0 wire size made of aluminum. Otherwise, a 1/0 is the smallest you can go with when looking at copper.
Suppose you have a circuit breaker at home with this rating, and you would like to use it.
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
The right 200 amp wire size is 250 made of aluminum or a 3/0 made of copper. Here’s a table with the different sub-panel and breakers we recommend for this power level.
Pros
- It arrived as intended.
- No complaints about the product we received.
- The price was fair, everything considered.
Cons
- It’s not always available for purchase on Amazon.
- Alternatives are hard to find on Amazon.
300 amp
For 300 amp service, you will want copper wire size 500 kcmil to handle the load.
400 amp
The right 400 amp wire size requires an aluminum wire size of 1000 kcmil. In contrast, a copper 600 kcmil can handle that amount of power. Take a look at the NEC electrical cable chart below.
600 amp
The right wire size for 600 amp service is at least 1500 kcmil assuming a temperature of 167°F for the conductor.
Full wire size chart
Check the chart below to find the right wire size for 70 or 80 amps. We have the right wire size for you if you need something more substantial, like 100, 125, or 150 amps. Scroll down further if you need the wire size for 200, 300, 400, or 600 amps.
| Max amp for | Aluminum | Max amp for | Copper | Our recommendation | ||
| Wire Gauge | 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 diameter of the product. 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 comes in several options.
Instead of referring to its actual thickness, people use its gauge. 6 and 4 are just some of the numbers you’ll encounter. You could also come across gauges like 1/0, 2/0, and 3/0.
It is inversely proportional to the diameter. It 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 tool 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, consider how much electrical current it can handle by identifying the devices you will use.
The United States and 65 other countries use the AWG as the unit of measure. Other countries use the Imperial Standard, defined by the British Board of Trade.
Make sure to read two of our other resources on Thermo King alarm codes and an in-depth look at welding gas or welding glasses.
Choosing the right one
They usually burn 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. He’ll have all the necessary information and be able to pull the necessary permits. There are many reasons and situations where you want to hire a pro.
They have all their information in order and know everything there is to know about wiring size requirements and breaker amps. For instance, would you have thought about the importance of a grounding electrode, and do you know what romex wire is?
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 different electrical components always need to be compatible with one another.
If you have a 60 amp circuit breaker for your water heater, read the next section as we guide you to understand the basics. We’ll ensure you know which products go with your clothes dryer or air conditioner.
