Class M vs. Class K Welding Cables: Which One Should You Choose?

Class M vs. Class K Welding Cables

A welding cable, also known as a welding lead, is a special type of electric cable used to connect a welding machine to an electrode holder or clamp. The cable transfers electrical energy generated by the welding machine to the electrode holder, which then converts it into an electrical arc or heat to melt and fuse two metals together.

Welding cable are categorized into different classes, depending on factors like their current-carrying capacity, gauge and voltage rating. As a welder, two of the most common classes of welding cables that you’re likely to come across are Class M and Class K cables. Here’s a detailed comparison between these two commonly available classes of welding cables.

Class M vs Class K Welding Cables: A Detailed Comparison

Although both Class M and Class K cables may have similar physical appearances, there are some significant differences that set them apart. Here is a closer look at these differences between Class M and Class K welding cables.

●       Strand Gauge

Similar to most traditional electrical cables, Class M and Class K welding cable also feature a stranded copper conductor. However, the difference between the two cables lies in the strand count — which is measured in AWG or American Wire Gauge. AWG measures the thickness of wires; the larger the AWG, the thinner the wire strands are and vice versa. The copper strands in Class K cables are 30 AWG, whereas the strands in Class M cables are 34 AWG.

●       Flexibility

Since Class M cables feature thinner 34 AWG copper strands, they’re far more flexible than Class K cables, which use the thicker 30 AWG copper strands. This makes Class M cables far more versatile and well-suited for a wider range of welding jobs than Class K cables.

●       Durability

Although Class M cables feature thinner strands, their strand count is greater than that of Class K cables. These additional strands enhance the durability of Class M electrical cables and make them more resistant to heat.

●       Insulation

Another major difference between Class M and Class K welding cables is the outer insulation that they come with. Class K cables feature a thermoset jacket made from Ethylene Propylene Diene Monomer (EPDM) Rubber.

Class M cables, on the other hand, feature thermoset jackets made from EPDM or other tougher materials like Neoprene and Super Vu-Tron. All in all, Class M cables with Neoprene and Super Vu-Tron jackets come with better resistance to abrasion, cuts and punctures.

●       Temperature Rating

When high amperage current is passed through an electric cable, it generates heat. The welding cable you choose should be capable of withstanding such high temperatures. In this aspect too, Class M and Class K welding cables differ from one another. While Class K cables have a maximum temperature rating of 90°C, Class M cables are rated to withstand temperatures of up to 105°C.

Which Class of Welding Cable Should You Choose?

Ultimately, the choice between Class M and Class K welding cables depends on the specific needs of your welding application.

For instance, if your welding job demands flexibility and maneuverability, opting for a Class M cable may be the right choice. Additionally, Class M cables are ideal for rugged work environments and heavy-duty welding applications due to their tougher and more durable thermoset jackets.

On the other hand, Class K cables are more suitable for light to moderate welding applications. Furthermore, they’re relatively inexpensive and more widely available when compared to Class M cables.


Both Class M and Class K welding cables are rated for up to 600V, making them ideal choices for a wide range of welding applications. However, despite their similarities, there are several structural and functional differences between the two.

Therefore, before deciding on the type of cable for your welding setup, make sure to thoroughly assess your requirements. This way, you can ensure that you get the most suitable welding cable for your welding job.