> That's what Lincoln says - 45-amp wire feeding a machine that pulls up to 65
> or 72 amps, protected by a slow-blow 125-amp breaker. Whaaaaat???
>
> I sure hope someone can explain this -- I'm really curious how these specs
> can be right.
I'm not an electrician, and I try not to play one on the net, but
I think this is all about duty cycle. Ampacity ratings for a particular
wire gauge are typically based on continuous duty - and the goal
is that they don't get so hot that they melt the insulation. Welders
don't run at 100% duty cycle - some run as low as 25% - so the
wire and insulation don't generate as much heat.
This was even legal in the NEC when I last looked it up, some 5-8 years
ago (when I put in a circuit for my welder-to-be ... which I still
don't have).
My read of those specs is that the welder may pull up to 125A *momentarily*
in normal operation, but the overall current draw will be similar to
continuous 45A.
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