Keeping it simple is a good rule to follow most of the time, and it certainly applies to safety padlocks and keys, as well as lockout steps for equipment maintenance.
Worker safety relies on the rare tandem of key integrity and precise lockout procedures. Depending on the type of facility, this usually involves machines and a host of production equipment. Items such as pumps, boilers, air handler units and hot water heaters have multiple energy sources — electrical, water, gas, steam — or different power connections like circuit breakers, valves and plugs.