Fronius MMA Cable Sets FAQs
Cable sets for manual metal arc (stick) welding: what they contain and how to choose, fit and look after the leads, plugs, holder and clamp.
How do I choose the right cable cross-section?
Cable size is given as the cross-section of the copper conductor in square millimetres. A larger cross-section carries more current. Cable that is too small for the current will overheat, which is a fire, cable failure and shock risk, while cable that is bigger than needed gives no better welding.
Match the size to the maximum output of your welding machine and the duty cycle you will actually use, using the cable maker's rating chart. Length, insulation temperature rating and ambient temperature also affect how much current a cable can carry safely.
Does lead length matter?
Yes. The electrode lead and the return lead together form the welding circuit, and the total length of both is what counts. Longer runs lose more voltage along the cable, so longer leads usually need a larger cross-section to compensate.
Use leads only as long as the job needs. If you regularly work a long way from the machine, step up to a larger cable size instead of simply joining extra lengths, and check connections, as each joint adds resistance. Check your machine's manual for any maximum lead length it recommends.
How do I know which plug size I need?
Plugs are sized to suit the cable cross-section, and each plug size covers a range of cable sizes, so check the range given by the plug maker. The plug must also match the socket on the welding machine, so check the machine's manual for the socket type.
Choose a plug that suits both the cable size and the current it will carry. A plug that is a poor fit for the cable, or one that is not fully inserted and locked, can make a poor connection that gets hot. Fit and tighten plugs so they make full contact. Labelling varies between makers, so if you are unsure, check the plug maker's details.
Where should the return clamp be connected?
Connect it to the workpiece as close to the arc as is practical, onto clean, bright metal. Remove rust, paint, mill scale or primer where the clamp bites, because these conduct poorly and add resistance.
Do not let the return current pass through metal rails, pipes or frames that are not part of the workpiece. Keep the clamp tight, as a weak spring is a common cause of poor contact. Check the clamp is rated for the current in use, as an undersized clamp can overheat.