219 / | HD | ELECTRIC HEATING |
50 | DF | METAL HEATING (E.G., RESISTANCE HEATING) {19} |
121.11 | DF | .~ By arc {16} |
130.1 | DF | .~.~ Including arc-power supplies {5} |
130.21 | DF | .~.~.~ With automatic output control (e.g., shortcircuit, infrared) {3} |
130.31 | .~.~.~.~ Responsive to arc voltage only |