How Many Amps are Needed for a MIG Welder?

By ced •  Updated: 07/13/21 •  6 min read

This is a question I get asked a lot. Basically, it’s all about how much power I need to run my welder; the short answer is, “it depends”. The long answer is below.

What Manufacturers Recommend and What You Need

Each manufacturer has its own guidelines for how much power you should use for various applications. It is important to know that these guidelines may be quite different from one manufacturer to another, so don’t take them at face value but rather do some research on your particular application. I have listed the guidelines below along with my personal conclusions as to what they mean and what you should do with them.

The first thing we need to find out is what output rating we want from our welder. The output power of your welding machine will depend on a number of factors, including the type of metal being welded, the thickness of the metal being welded, and the size of the welding gun used.

Electrical Ratings

I will start with the basics. The electrical ratings given to a welder are basically how much power the welder can use before it is damaged. The ratings are given by amperes (amps) and voltages. Amps measure the rate of current flow, while volts measure how much pressure is pushing on your welds. The voltage rating is an important consideration when choosing a welder because it indicates how much heat you can put on the metal while welding at various settings. The higher the voltage rating of a welder, the more heat you can put on your metal without damage or melting your equipment.

I have listed two examples below for reference; these are not meant to be exact numbers but are just guidelines.

Example 1

Say you have a welder that has an amperage rating of 30 amps. This would mean that the arc produced by this welder will last for approximately 30 seconds before it shuts down (I will explain in more detail below). This is a relatively low-power welder, but it would still be able to weld some mild steel without damaging your equipment. The voltage on this welder is not important since the amperage rating is high enough to avoid any damage to your equipment. I would recommend using this welder for projects that are not too tough and only need to be welded for around 30 seconds at a time.

Example 2

Say you have a welder with a rating of 100 amps. The amperage rating is low, but the voltage is also low. This means that your arc will last between 1 to 5 seconds depending on your settings. This means that if you want to weld thicker steel or use heavier-duty equipment it may not be able to do this effectively. I would recommend using this welder for mild steel applications that require some welding power without causing damage to your equipment. You can also use it for small projects where the job takes less than 5 minutes with no cooling or fanning.

How Power Can Be Calculated

Power can be calculated in two ways: by calculating how many amps you are using or by using a power chart. I will explain how to do the latter in another article. Let’s take a look at the two ways of calculating power in more detail.

Calculating Power Using Amps

Calculating power using amps is very simple; all you have to do is divide the amps by the amount of time you are welding. This will give you their equivalent kilowatts (kw). With these numbers, you can perform calculations such as “how many kw does my welder need?” etc.. This is a good way to determine if you need more power or not.

Calculating Power Using Watts

The amount of power needed to weld a given metal depends on a lot of factors. As I mentioned earlier, your specific welder will have its own recommended power ratings. I have also listed below what each manufacturer recommends as their equivalents in kw (kilowatts). You can use these numbers to find out how many kw you need for your specific welder. To do this, just multiply the kilowatts by the amperage rating of the welder to get the equivalent amps. If you are using a 2-phase welder and it’s recommended amperage is 30 amps then you would know that it needs 750 watts.

Amperage Equivalent Watts

If you are using a 2-phase welder, you will need an amperage of 100 amps. This means that you would need a 2-phase welder that can produce 750 watts. If your welder is single-phase, then multiply the kilowatts by 50 to find out how many amps you need.

Here are some basic guidelines for welding projects:

Residential

For residential welding projects that will only be used on mild steel and aluminum, it is recommended that you use a 20 amp circuit with an output rating of at least 75 amps per phase. For greater power requirements, you can wire up two circuits in parallel: one for each side or both sides as needed to provide more current flow in a shorter period of time.

Commercial

For commercial welding projects, you can wire up two circuits in parallel which will provide for greater current flow with minimal voltage loss. The 20 amp circuit should be used as the minimum size circuit for residential use. For commercial projects that require a higher pressure of current, a 25 amp or 30 amp circuit should be used. For even greater power requirements, you can wire up three circuits in parallel to ensure that the voltage loss is minimized and that there will not be any lack of power if one of the circuits is damaged. This is a great idea if your welder has an overload protection feature, but if the welder does not have an overload protection feature it is best to always use at least two different circuits in parallel if you are increasing the power output.

Industrial

For industrial use, the 30 amp circuit should be used for residential use. For commercial and industrial projects that require a higher pressure of current, a 40 amp circuit should be used. For even greater power requirements, you can wire up four circuits in parallel which will ensure that voltage loss is minimized and there will not be any lack of power if one of the circuits is damaged.

(Visited 490 times, 1 visits today)

ced