Digging a little further into this, it is not just one brand of welder that is guilty of overloading supply cords and outlets, it would seem to be endemic.
This, from the sales brochure for the SteadyMig 206, sold by one of NZ's biggest welding supply current : "Input Rating @ 230V Single Phase : 3.5KVA @ 95A 18.8V, 15A Primary Draw".
Since this welder is good for "60% @ 125A, 20% @ 200A", it seems a safe bet that at 125A the primary draw is nearly 20A and at 200A just over 30A. This welder is supplied with a factory-fitted 15A plug and cord.
Even the 206's little brother, the 165, will draw a calculated 22A at full output.
I do not think that these are isolated cases, it looks like the formula that is being applied in the welding industry is that the primary draw x duty cycle must be no greater than the rating of the plug and socket.
I am going to inquire about this with the Energy Safety Service. I will post their response when I get it.
