Sizes of DINSE Plugs, Connectors, and Sockets
I looked up DINSE SKS 120 plug and found on the American website 2 different versions of the same PDF document and on their European website 2 different PDF files one of which explains some things about sizes.
There are 3 different diameter pins for the plugs and male power inlets. The smallest is 9 millimeters diameter, the medium is 13 mm diameter, and the large 120 size is 15 mm. The largest plug is the SKS 120 and the corresponding panel socket socket BES 95/120.
There are 3 different size adapters. The RSS 50/25 is 13mm female 9 mm male. The RSS S50/B25 is 9mm female 13 mm female. These are sold by Everlast as well as a number of other vendors. The RSS 95/120 13 mm female 15 mm male so that cables 2/0 copper or smaller can be plugged into the BES 95/120 female panel mounted socket.
If you really need to use 3/0 or 4/0 copper welding cables ( and I doubt that you would need to do this ) with Everlast welders there are 3 options. One of them is to retrofit the welder with the BES 95/120 socket. Then, use 15 mm male 13 mm female adapter for smaller welding cables. The second is that the SKK 95 plug and the BKS female cord connector will both take 3/0 copper. The third if you believe in using antioxidant compound such as Ilsco Deox(R) that is listed for use on copper is to put 2/0 copper into the plug, 3/0 copper into the large connector, then use a split bolt connector to put the 2 together. Then, tape with Scotch 88 electrical tape which has a broader range temperature than Scotch 33.
The probably cheaper option would be to use a 6 or better yet 4 gauge extension cord and move the welding machine. This would put the voltage drop on the higher voltage lower current side of the machine.
Mike Cole, Ohio Electrical Contractor License No. EL45,008.