i have never seen one caused from a welder wiring and I have seen some shady setups. On a buzzer light wire can work but there is such a difference in drop between a 12 and a 10 it just works better and isn't a worry should someone haul azz and exceed the duty cycle. Something to consider is on a machine with a factory cord its likely a 12 (250a feeders come bigger) but 12 with a 50a plug. The main reason the breaker is there is as a disconnect and to provide for short circuit interruption. This is a circuit for a welder, the wire is protected by the theory that the machine will overheat before it cooks the wire,,, in the real world not so good, a buzzer will run fine wayyyyyyy beyond its rated output, that could cause a problem.