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Class K vs Class M Welding Cable

In our This vs That series, we're comparing (and contrasting) two seemingly similar products. A lot of products seem the same at first glance but can greatly affect the outcome of your next application. Today, we're comparing Class K and Class M Welding Cables. They're very similar products, so how do you know which is best for your next application? Let's find out!

What is Class K Welding Cable?

Class K Welding Cable is considered the standard welding cable. It features a singular stranded bare copper conductor made up of 30 AWG strands. Like all welding cables, class K also features a thermoset jacket. Most Class K cables feature Ethylene Propylene Diene Monomer Rubber (EPDM) jacketing. They are also most commonly available in red or black jackets. These cables are ideal for use in secondary voltage resistance welding leads and power supply applications not exceeding 600V AC. It is also suitable for use as a battery cable.

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What is Class M Welding Cable?

Class M Welding Cable is the more flexible, more durable welding cable. It features also features a singular fully annealed stranded bare copper conductor, but it is made up of 34 AWG strands. This cable's smaller strands and higher strand count are what make it more flexible. Class M cables have thermoset jacketing as well, either EPDM or Neoprene. General Cable, a major supplier of these welding cables, makes theirs with Super Vu-Tron jacketing. These jackets are almost always orange to indicate a tougher construction, as well as for safety reasons.

This type of welding cable is also UL/CSA listed. They are suitable for use as battery cable, in secondary voltage resistance welding leads, and in power supply applications. However, sizes 1/0 AWG to 500 MCM may also be installed in conduit or trays in power supplies, hoists, cranes, and other applications that do not exceed 600V.

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What is the difference between Class K and Class M Welding Cable?

The main difference between these welding cables is in their stranding. Since Class M Welding Cable has smaller gauge strands, it is much more flexible. Class M Welding Cable also has a thicker jacket, which makes it more durable and allows it to have a higher ampacity than Class K. The last major difference between these two types of cable is their price. Since Class M Cable requires more copper and more jacketing material, it tends to be more expensive.

However, there are many similarities between these cables as well. Both cables have a maximum voltage rating of 600V. Maximum temperatures also always fall between +90°C and +105°C depending on the manufacturer. Both are also commonly available in the same gauge sizes, from 6 AWG to 500 MCM. They also share the same basic construction of a bare copper conductor and thermoset jacket.

Allied Wire and Cable carries an extensive stock of Class K Welding Cable and General Cable Class M Welding Cable. To learn more about Welding Cable, you can read our Welding Cable FAQs and our Welding Cable Specifications Article. Have more questions? Contact us today!