Gasless ('MIG') Welding – What is the correct polarity?

Date: 17-01-2018

Can’t remember which terminals the torch & earth clamp go to?   Wire not running properly?   Poor penetration?

Don’t stress – even the most experienced welders can get it wrong!  If your gasless welding wire is not running properly, or has poor penetration, then there’s a good chance that the polarity is wrong.

When running gasless welding wire – connect the Earth to positive and Torch to negative, otherwise known as "DC electrode negative", or "straight polarity".

(This is the opposite to standard MIG welding with gas, which is torch/wire positive and earth negative).


Earth to Positive (+)

Connect the earth lead to the positive (+) terminal on the front of your welder.




Torch to Negative (-)

The polarity connections for the torch are commonly found either on the inside of the welder (near the wire drive system as shown below) or on the front of the welder.
Usually there will be a short lead that can be connected to either a positive or negative terminal.  Connect this to the Negative (-) terminal. 


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This blog is intended to help with:  What is the correct polarity for MIG welding without gas? // Where should I connect the earth lead when using gasless MIG wire?

While all care has been taken, Weldclass accepts no responsibility for any inaccuracies, errors or omissions in this information or links and attachments. Any comments, suggestions & recommendations are of a general nature only and may not apply to particular applications. It is the sole responsibility of the user and/or operator to select the appropriate product for their intended purpose and to ensure that the product selected is capable of performing correctly and safely in the intended application. E.&O.E.

  • Date: 06-03-2023
    Bill Wallis Golden Bay Piano Service

    I don't know how I accomplished any MIG welds at all without switching the polarity cables that I just discovered beside the spool of wire, but am sure it'll work better than the struggle I was having after reading this article. Cheers, Bill on the hill still
  • Date: 20-04-2020

    Hello Graeme, thank you for your question. If your MIG welder does not have +/- terminals (either inside or outside the machine), then unfortunately there is no way to change the polarity. These days the vast majority of MIG welders will have ability to change polarity, due to the popularity of gasless wire. If you are looking for a portable 240V machine to run off 10A power, our 180MST machine is very popular for both gas & gasless work.
  • Date: 18-04-2020
    Graeme Coates

    Hi, I have a mig welder with no + or -- plugs to swap for gasless welding. Can the polarity still be changed? Any help would be greatly appreciated. Thankyou in advance Graeme
  • Date: 04-12-2019
    Bruce Spence Community College Northern Inland

    Hi, I've found my way to your site to verify, for our students, what we talk about in our training when we are discussing "gasless" wires. But there are a few things that seem to persist that should not when we are talking about welding. The return lead is NOT a ground. And, as well, the material we weld on is the parent metal NOT base metal. We seem to adopt American terminology that is not covered under our welding codes. It is confusing enough to explain the field of welding without adopting incorrect information. These are just two examples, there are many more.
  • Date: 08-04-2019
    Matthew welderpedia

    Hi, there I really enjoyed your information about all the different types of welding. I am not a certified welder but am self-taught and the issues I had when I was trying to learn MIG welding was knowing how to set up my machine. But luckily I found some real information on google and youtube. I would suggest to anybody learning welding to find some good information online first this will make the process a bit easier.