Arcing to gun?

[Robotstar5]

Also the case isn't connected to welding earth so it doesn't matter if the live wire touches the case during a birds nest situation.

I reckon the motor will be isolated to stop the case becoming live rather than preventing a short to earth.

Unless the case is against the workbench like a couple I've had at work, the hot wire made a right mess of the plastic wire feed housings

 

[rtbcomp]

Unless the case is against the workbench like a couple I've had at work, the hot wire made a right mess of the plastic wire feed housings

Yes, a case for not putting the welder on the bench, as mentioned in one or two other threads

 

[Robotstar5]

Yes, a case for not putting the welder on the bench, as mentioned in one or two other threads

I sometimes wonder about our "welders", I reckon if the torch wasn't a nice blue colour they wouldn't know which bit to hold

 

[arceyered]

As stated by the replies before the power is transfered at the tip and no where else .
also the feed roll assembly should be insulated from the rest of the machine we used to have this problem when rubbish broke down the insulation on the feed roll assembly. ie bits of wire and grinding particals wedged down the feed roll assembly

 

[KemppiFrog]

Think about it, if the power was at the rollers, the whole wire from then on is carrying the amps. So would melt anywhere along the feed, not just at the tip/surface. The roller section needs to be isolated to avoid the connection to earth through the chassis, which must be earthed for safety reasons.
KF
BTW, I had a problem with my first 100amp hobby MIG that caused the wire liner to melt. So, bin there, dun that.

Think the question has been answered above with the shroud shorting.

 

[rtbcomp]

........ The roller section needs to be isolated to avoid the connection to earth through the chassis, which must be earthed for safety reasons.
..........

Yes, but the welding and safety earths are separate.

Isolating the rollers stops the chassis becoming live just in case the box comes into contact with the workpiece or welding earth.