The correct polarity of the ground cable is crucial for a clean weld appearance and a stable arc. The polarity varies depending on the welding wire or material used.
Below you will learn how to correctly connect the ground cable on RED by Lorch MIG/MAG welding machines with polarity reversal device.
Polarity of the Ground Cable
The polarity depends on the type of wire used.
The earth/ground cable is connected either to the negative pole (–) or the positive pole (+).
The other pole is occupied by the polarity reversal device or the torch connection.
Solid Wire, Rutile and Metal Powder Flux-Cored Wire
Connect the ground cable to the negative pole (–) socket and secure it with a clockwise turn of the plug.
The plug of the polarity reversal device is connected to the positive pole (+).
Typical application:
This polarity (wire positive) is used for most MIG/MAG welding tasks with shielding gas. It ensures a stable arc, good penetration, and clean seams.
Suitable for:
Structural steel
Stainless steel
Aluminium (with shielding gas)
Structural Steel
Structural steels are unalloyed or low-alloy steels that are easy to weld.
With shielding gas (e.g. CO₂ or argon mixture), good seam quality and stable arc control are achieved.
Polarity: Torch/Positive – Ground/Negative
Stainless Steel
Stainless steel is also welded with shielding gas (argon + CO₂ or argon + O₂).
The positive torch polarity ensures a concentrated arc and clean, low-spatter seams.
Pay attention to moderate heat input to avoid discoloration.
Polarity: Torch/Positive – Ground/Negative
Aluminium
In aluminium welding (MIG), solid wire (e.g. AlMg or AlSi) is used with argon or argon mixture gas.
The polarity with wire at the positive pole ensures optimal penetration and a stable arc.
Polarity: Torch/Positive – Ground/Negative
Self-Shielded Flux-Cored Wire (Flux-Cored Wire without Gas)
Connect the ground cable to the positive pole (+) socket and secure it with a clockwise turn of the plug.
The plug of the polarity reversal device is connected to the negative pole (–).
Typical application:
This polarity (wire negative) is used when welding without separate shielding gas.
It ensures a stable arc and sufficient penetration, even under adverse environmental conditions.
Suitable for:
Structural steel outdoors
Repair work outdoors or on construction sites
Situations where wind or drafts might disturb the shielding gas coverage
Summary Table: Wire Types and Polarity
| Wire Type / Material | Shielding Gas Required | Torch / Wire Connection | Ground Cable Connection | Typical Application |
|---|---|---|---|---|
| Solid Wire (Structural Steel) | Yes (CO₂ or Ar mix) | Positive (+) | Negative (–) | General welding tasks, workshop |
| Stainless Steel (Solid Wire) | Yes (Ar + CO₂ / O₂) | Positive (+) | Negative (–) | Thin & stainless steel sheets, constructions |
| Aluminium (Solid Wire) | Yes (Argon / Ar mix) | Positive (+) | Negative (–) | Aluminium components, bodywork, workshop |
| Rutile/Metal Powder Flux-Cored Wire | Yes (CO₂ / Ar mix) | Positive (+) | Negative (–) | Low-spatter seams, good appearance |
| Self-Shielded Flux-Cored Wire | No | Negative (–) | Positive (+) | Outdoor, assembly, repairs |
Notes
Ensure that the plugs fit firmly – a loose contact can cause disturbances, unstable arc, or error messages.
Keep contact surfaces clean: Remove dirt, oil, or rust from the connections.
Always use the recommended polarity for your wire type to avoid material defects and excessive spatter.
If you are unsure which polarity you need for your material or wire, consult the operating manual of your RED by Lorch device or send an enquiry via the contact form.