[682bear]

Yesterday I was welding a piece of 1/2 x 2 inch flat stock to some 2 x 3/16 wall square tubing. I use a Millermatic 211 and had it set for 3/16 material thickness with the autoset feature and .030 ER70S-6 wire...

After welding about 16 inches, I went to move my ground clamp to a different place and noticed that the ground wire was warm all the way back to the machine. Is this normal? I haven't noticed that happening before, but I don't usually weld material thicker than 1/8 inch except in short beads...

I've always been told if a wire heats up, then it is too small to carry the amount of amps that is being required of it...

Thanks- Bear

[Poland308]

It might also be from a bad clamp. Either a weak spring or just a bad connection either at or in the welder or at the work piece. Were you clamped directly to the part you were welding? Warm is not bad but keep an eye on it.

[682bear]

Yeah... I had the ground clamp attached directly to the workpiece.

-Bear

[DLewis0289]

Amperage, current (I) is heat. Cable undersized for amperage. Loose connections (high resistance). Welders have a special place in the NEC (NFPA 70), there is accommodations (de-rating) built around duty cycles.

Inspect for loose connections, verify cable rating for ampacity.

[Otto Nobedder]

If the whole cable is warm to the machine fitting, I'd disassemble, clean, and retighten were the cable goes into your Dinse connector at the machine. (If the trouble is at the clamp end, only the clamp and a few inches of the cable get warm). Also inspect the mating surfaces of the Dinse connector, and clean as needed. If this doesn't fix it, you may have to open the machine and check it's side of the connection for cleanliness/tightness.

Some warmth is normal if you're welding at the top end of the machine's ability, but with the 251 I have to do spray-arc at 250A for several minutes for the cable to be noticeable warm.

Steve S

[The_Fixer]

Steve is correct.
Highest heat buildup will be at the point of highest resistance...ie. poor connection.
Check for oxidation of wire and connector. If the wire is discolored, cut it off back to clean point and reconnect.
It is also correct that the wire will warm up if used at the high end of current capacity. Getting very hot is a sign of trouble though.

Many cheaper welder manufacturers will provide an undersize return (earth) wire on their welders sometimes, in which case probably better to replace it with a heavier duty one.
Having said that though, duty cycle comes into this. This where at the higher power end of usage, you may only be able to weld for a minute or two, and let the machine rest for a few.
There have been instances (not me I tell you) when this has been pretty frustrating and the side panels got taken off the welder and a heavy duty fan was placed over the power unit to force cool it. It would run much longer before the thermal cutout would kick in and it would cool down much sooner.
Not really recommended practice, but it did save waiting around all day for the welder.

[682bear]

This machine doesn't have a dinse connector on the ground cable... it is a #6 AWG cable that runs through a hole in the front panel and attaches to a lug inside the side panel. I think I will make up another ground cable out of the largest wire that will go through the hole in the front panel without modifying it... probably a #4... and get a better ground clamp while I am at it.

The machine is practically new, it has only had two 2lb rolls of wire through it... I checked the connections at both ends of the cable and they were both tight.

Thanks- Bear

[Otto Nobedder]

Good plan. #6 isn't much of a ground wire for the 211 at it's high end. The heavier the ground, the better.

Steve S

[DLewis0289]

#6AWG ?????? gotta be a misprint........go 1/0