@poncho62 If you do end up reconfiguring your leads, consider some or all parts of the following plan:
1. Make quick disconnects at the machine itself. Commercial and industrial power supplies, as well as engine drives, already have studs or quick disconnects. But some of the home / farm / hobby power supplies do not, such as the ubiquitous Lincoln tombstone (not the curved top Idealarc, but the angle top AC225 and AC/DC 225) that have the leads directly wired in to the machine. If you are going to be swapping built in leads around anyway, why not install cabinet mounted through panel disconnets, or install very short 6" leads out of the machine with Tweco or Lenco camlock disconnects, clearly marked positive and negative.
This has several benefits. The machine can be moved easier, because it can be readily divorced from the leads for transport and rapidly reconnected again. The weight of the heavy leads can be separated from the weight of the heavy transformer, which sometimes makes a big difference in being able to move the thing from point A to point B, the older we get (I've noticed many of the members here are retired, not strapping young lads). The other benefits of quick disconnects at the machine itself (if yours doesn't already have them) will become self-evident in the subsequent points below.
2. Make two whips. A work clamp whip, and a stinger whip. The whips can be between 8 to 15 feet long. I'd aim somewhere in the upper middle, around 12' long, but the exact length chosen might be influenced by what cable you can obtain, recycle from the machine being modified, or already have on hand. Ideally, the whips should be of lighter, more supple cabling, with higher, thinner strand count for flexibility, and EPDM jacketing for suppleness. These whips are short leads, so they'll be by you at all times, not being run over by a forklift 100 feet away. The exact gauge size will be dictated by the maximum current output of your machine, but the idea is to meet the gauge requirement only for the short distance between the machine and the end of the whip.
3. Make two heavy leads, with quick disconnects at each end, male on one end, female on the other. These heavy leads can be anywhere from 20' to 50' long. If I make anymore of these for myself, I'd probably make them 25' long. These should be heavy gauge, in the aughts if you plan on making more than just two and daisy chaining them, as
@hill-billy and
@welding seabee described in their war stories from work posted previously above. With a constellation of at least two of these heavy extension leads and your light whips, you'll have between 30' to 60' of reach away from the machine (depending on how long you choose to make your two classes of leads).
You can't lose with this set up... except for the costs of the cable and the constellation of quick disconnects to make it. But these costs can all be recouped by selling the leads individually or as a set separate and apart from the welding machine itself, because the leads can be used on any machine.
With easily separable leads, you only need run the length of lead that you need. In a home shop environment, it will usually only be the two whips. But if having to weld a metal gate post on the fence line, the welding machine can stay put, and the heavy leads can be rolled out as required, with the light whips clicked in at the ends of the heavy leads. My DC power supply doesn't have a polarity switch, but the quick disconnects enable me to easily change polarity when desired. The welding set up can also be stored more compactly, by not having all the lead roped around the power supply.
Just a suggestion, if you are planning on reworking the leads to your machine anyway.