Originally Posted by jss12
llincoln just replied saying I need 8gauge wire and 125 amp breaker.
this once again makes no sense to me
Why not? You have to stop thinking inside the box on such installations, and follow the Code.
Section 240-4(D) does not apply here.
You are under 240-4(G), and that section refers to article 630. There are specific guidelines for welder circuits, and they have already been pointed out to you. The manufacturer has also confirmed their circuit chart is correct.
Just be sure that your #8 wire is installed in conduit.
630.32(B). For Conductors. Conductors that supply one or more welders shall be protected by an overcurrent device rated or set at not more than 300 percent of the conductor rating.
Table 310-16 shows that #8 THHN wire is capable of carrying 50 Amps. Same size as your receptacle and cord and plug on the welder, BTW. Multiply that by 3 and your max breaker size could be as high as 150 Amps. Since the manufacturer has already done the other duty-cycle calculations for this unit, they have determined that a 125 Amp breaker is sufficient.