R 408.40743 Design requirements for arc welding machines.

Rule 743. (1) A controller integrally mounted in an electric motor-driven welding machine shall have the capacity for carrying rated motor current and shall be capable of making and interrupting stalled rotor current of the motor. (2) Input power terminals, tap change devices, and live metal parts connected to input circuits shall be completely enclosed and shall be accessible only by use of tools. (3) Welding lead terminals shall be protected from accidental electrical contact by personnel or metal objects. If a welding lead terminal normally used for connection to the work is connected to a grounded enclosure, it shall be done by a conductor not less than 2 sizes smaller than the grounding conductor and it shall be so marked. (4) Portable control devices, such as push buttons, shall not be connected to an AC circuit of more than 120 volts. Exposed metal parts of a portable control device operating above 50 volts shall be grounded. (5) Auto transformers or AC reactors shall not be used to draw welding current directly from any AC power source having a voltage of more than 80 volts.