WoW! I wonder what the voltage reading is from that reel to earth ground when the welder is running...looks like a transformer ready to melt, haha

well i see two problems, he has the wires mixed up . if this is a 120 volt plug. he should have used the bare conductor on the green screw & cut the red .or bought some 8/2 w grd & reidentified the white.if this is a 240 volt welder he should have bought a 4 wire male & female plug & wired them correctly.then hooked them too the welder.but if memory serves me right most welder only need 2 hot wires & an equipment ground. seems i have seen a few that do use 4 wires. please correct any mistakes i have mentioned.

The 50 A. 250 V. config. is the only thing correct about that abortion, NM used in place of a proper flex cord, botched color code, and the worst is the use of a surface mounted receptacle for a cord connector,when they are dropped (not if, when) they shatter leaving exposed live parts for the user to contend with.

Note: Arrow Hart makes a connector ( AH6709N) that would be more OSHA "friendly" then a 4 square box / raised cover / receptacle combo.

I can't count on both hands and both feet how many times I have been in welding shops and seen something like that, where they have used romex as a cord..
Albeit the wrong cable, that rack is actually grounded if you look close at the receptacle the ground contact is actually riveted to the metal backing of the receptacle and that in turn is bolted to the "rack".. and really, those receptacles even though they are not a proper cord " connector", the ones made by leviton are NOT bakelite (read "will shatter") anymore.. They are made of nylon... I have personally kicked one across the shop and into a block wall with no damage resulting!
IMHO, That wouldnt really be a bad rack, I would just put on the proper cord and NOT use it unless all of the cabtire was spooled out first, to prevent heat from building up in that "coil" of cord...

A.D

AD, I'll bet that rivet only goes through the plastic base and not all the way to the backing plate. I've never seen one grounded the way you're describing. I'll check a new one next time I'm in the store.

We have a real welder extension, and legal to boot.
125 ft of 6/3 SO, with rubber clad straight 6-50 caps, designed for portable cord assemblies.

It is rolled up onto a large tire rim, fully unrolled to use, although we haven't used it much since we got the long electrode leads on the welder.