These methods also require removing and replacing much more dirt than shoring or a trench box. Contact utility companies to locate power lines before digging. The OSHA regulation to protect workers from the hazards of excavation and trenching work is 29 CFR 1926.650-652 . Others have burned to death or drowned when a valve was opened when it should have been closed. These types of incidents happen most often while machinery is being repaired or maintained.
Electricity is the most common type of energy used to run machinery.
Hydraulic, pneumatic, mechanical, heat or chemical energy are other types of energy that are used to run equipment. In this method, a tag is attached to the switch, circuit breaker or valve when the machinery is turned off. The purpose of the tag is to keep it from being used until the tag is removed. Figure 6 shows a valve that is locked out and tagged out. Figure 6 Lockout is safer than tagout.