The locks and tags are to be applied to a machine’s “energy isolating devices.” These are mechanical devices that prevent the flow of energy to the machine. OSHA says that an energy isolating device could be “a manually operated electrical circuit breaker; a disconnect switch; a line valve; a block; and any similar device used to block or isolate energy.”
Examples of what are not energy isolating devices include “push buttons, selector switches, and other control circuit type devices.” The buttons, switches, and dials on a machine’s control panel are not energy isolating devices.