In electrode welding (MMA), the correct polarity of the ground cable is crucial for stable welding behaviour and clean seams. Which polarity must be chosen depends on the type of electrode used. Some electrodes are operated at the positive pole, others at the negative pole.
Further information on selecting and the properties of various electrodes can be found in the article “Electrode Knowledge”.
Effect of Polarity
In MMA welding, the current flows between the electrode and the workpiece (ground connection).
The polarity influences where the main heat is generated:
Electrode at the negative pole (–) → more heat in the workpiece → deeper penetration, electrode stays cooler
Electrode at the positive pole (+) → more heat at the electrode → more stable arc, smoother control, but less penetration
Since different types of electrodes have different coatings, they have different requirements for current direction.
Therefore, it is important to observe the polarity recommended by the manufacturer.
Connecting the Ground Cable
According to the specifications of the electrodes, the electrode holder is connected to the positive or negative pole socket, and the ground cable with clamp is attached to the opposite pole socket.
Positive Electrode (Electrode at the Positive Pole)
→ Connect the ground cable to the negative pole (–) socket and secure it with a clockwise turn of the plug.
This polarity is used with most common electrodes (e.g. rutile and basic electrodes).
It ensures a stable arc, even seam formation and good penetration.
Negative Electrode (Electrode at the Negative Pole)
→ Connect the ground cable to the positive pole (+) socket and secure it with a clockwise turn of the plug.
This polarity is used with certain special electrodes or thin-walled workpieces,
to reduce heat input and avoid burn-through.
Notes
The correct polarity is indicated on the packaging or the electrode datasheet (e.g. “+”, “–” or “+/–”).
Incorrect polarity can lead to porosity, unstable arc or slag defects.
Ensure that the ground cable is connected firmly and cleanly – poor contact causes voltage fluctuations.
If you are unsure which polarity your electrode requires, take a look at the articles “Electrode Knowledge” and "Electrode Welding (Basics)" or contact us directly via the contact form.