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What Size Wire for Welder Extension Cord? (Detailed Answer)

Written by Edwin Jones / Fact checked by Andrew Wright

what size wire for welder extension cord

One of the most important aspects of using a welder is selecting the proper wire size for its extension cable. This is because the wire affects the safety and functionality of our equipment.

In this article, I will cover the aspects to consider when determining what size wire for welder extension cord, as well as its amperage. I’ll also give you some useful tips, so make sure you read all the way through.

What Size of Extension Cord For Welding Machine?


When it comes to welding, having the proper equipment is crucial for the safety and result of the project. In this case, the extension cord must not be overlooked, since it normally draws a large amount of current.

In most cases, the extension cord gauge wire for welder is determined by the amperage and voltage of the machine.

However, as higher resistance may result in voltage drops, the cable length must also be considered. As a result, depending on the length needed, you may need to use a much larger wire than usual.

To give you an idea about the recommended extension size for various ratings of welding machines, below is the minimum cord size chart that you may use as a reference.

1. Welding Extension Cord Wire Size Chart

Power Supply Ratings Wire Gauge For Different Lengths of Extension Cord
Amperage (Amps) Voltage (volts) 25 ft 50 ft 75 ft 100 ft
15 amps 120 12 AWG 12 AWG 10 AWG 8 AWG
20 amps 120 10 AWG 10 AWG 8 AWG 8 AWG
30 amps 120/240 8 AWG 8 AWG 8 AWG 6 AWG
40 amps 240 6 AWG 6 AWG 6 AWG 6 AWG
50 amps 240 6 AWG 6 AWG 6 AWG 6 AWG

2. Types of Cords

Aside from knowing the size of the extension cord, it’s also a good idea to know which sort of cord is best for you. In this case, let me give you a general concept of the pre-made and DIY options, so you can determine which suits your needs.

Pre-made Extension Cord


Pre-made extension cords are those produced by various manufacturers and come with a plug and connector. Furthermore, these cords are available in a variety of diameters and lengths based on their amperage ratings.

If you need one quickly, this is the most convenient alternative. You can get a ready-to-use heavy-duty 240V or 120V welder extension cord with the AWG and length of your choice.

Additionally, this sort of wire usually delivers a high level of safety because all accredited producers put it through safety and durability tests. However, one drawback of this type is that it usually costs you more, especially if you need a larger size like 6 AWG.

DIY Welder Extension Cord


Pre-made extension cables are manufactured cords. Another alternative is DIY cords, which you need to create yourself. This simple task requires only a few supplies, such as electrical cords, a plug, and an outlet connector. Aside from that, you may need basic tools such as a wire stripper and screw sets.

When selecting this option, it is critical to be mindful of the rating of your materials. For example, within a 50-foot radius, you can only use a 10-2 wire for welder with a power rating of 120V for up to 20 amps. A welder with higher amperage will need a bigger wire.

On the bright side, this is an excellent solution if you want to save money. Just remember that when making a DIY extension cord, consider using a SOOW wire as it is flexible, unlike hard Romex, which is only suitable for fixed circuit installation.

The Importance of Wire Gauge Size and Amps

It is important to understand wire gauge and amperage rating, since a welding machine’s current output is more significant than its amperage input. For example, a 120V welding machine with a power input of 30 amp typically creates an output of 140 amps on average.

In this case, the wire gauge and amperage should be considered. Wire gauge refers to the thickness of the wire used in an extension cord, which also determines the amount of current it can handle without taking any damage. It basically means that thicker wires or a smaller number of AWG can carry more current.

Some Tips for Extension Cords


If you are new to electricals, specifically using an extension cord for welding power, it is necessary to have an idea of how to avoid potential hazards. Therefore, the following tips might be useful.


  • Be aware of the power ratings of your welding machine.
  • Use a circuit, including breaker and outlet ratings, equal to or greater than the power ratings of your welding equipment.
  • Use large, short cables to minimize voltage drops.
  • Use only heavy-duty extension cord
  • Always check if there is damage to your extension cord.


  • Don’t use a Romex or any solid wire as it is not flexible and durable enough for welding applications.
  • Don’t use a low-rated circuit that can’t support the power of the welding machine.
  • Don’t coil your extension cord as it can cause higher resistance, resulting in overheating of wires.
  • Don’t use a wire with no ground connection.
  • Don’t use any other equipment in a circuit where your welding machine is connected.
  • Don’t use a very long extension cord.

Frequently Asked Questions


Can I Run a Welder on Standard Household Outlet?

A lower voltage welder can usually be run on a regular outlet. However, when there are high voltage requirements (usually 220V), a 50 amp welder will not work on this circuit.

What Type of Plug Can I Use With 220V Extension Cord for Welder?

The type of plug used in a 220v welder extension cord depends on the rating of the welding machine. In most cases, it is a 3-prong NEMA 6-50P or NEMA 10-50P.

What Does a Welder Extension Cord 6/3 Mean?

The number 6/3 on the extension cord label typically refers to the size and number of wires. So, a 6/3 extension cord has a 6 gauge size and three strands of wire.


Knowing what size wire for welder extension cord to use can help make your welding works safer and more efficient. After all, the appropriate cord size will ensure a sufficient power supply and prevent electrical hazards.

Please note that the chart above is only the minimum recommendation for various welder ratings. If you need a cable for your welding application, I highly suggest using the largest recommended size for each voltage.

In this case, you can use 8 gauge for a 120V unit and 6 gauge for a 240V unit.

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