R 408.11272 Open circuit and no-load voltages of arc welding machines.

Rule 1272. (1) When an arc welding machine is operated without being connected to a load, the open circuit voltage shall not exceed the values shown in table 1 when rated voltage is applied to the primary winding or when a generator type arc welding machine is operating a maximum rated no-load speed. TABLE 1 MAXIMUM OPEN CIRCUIT VOLTAGES OF WELDING MACHINES Max. Open Circuit (no-load) Voltage Welding Current Manual and Semiautomatic Machines Automatic Machines ac 80 rms 100 rms dc > 10% Ripple Voltage 80 rms 100 average dc < 10% Ripple Voltage 100 average 100 average (2) When welding and cutting processes require values of open circuit voltages higher than 100, insulation or other means shall be provided to prevent the operator from making accidental contact with the high voltage. (3) Equipment working through resistors from DC trolley voltages of 250 to 600 volts shall have a protective device for automatically disconnecting the power during arc off periods. (4) Automatic control devices for reducing no-load voltage below 50 volts shall be provided where AC welding is to be done under wet conditions that could provide a shock hazard.