When employees perform maintenance on machinery or equipment, you must ensure that they know how to protect themselves from the release of hazardous energy. OSHA’s control of hazardous energy (lockout/tagout) standard at 1910.147 requires you to create procedures for employee protection.
Your primary tool for providing protection is the energy isolating device — a mechanical device (like a circuit breaker or disconnect switch) that physically prevents the transmission or release of hazardous energy. A simple on/off switch might turn off the power, but it does not isolate the equipment from the energy source.