Any isolation of energy systems, such as mechanical, electrical, process, hydraulic, and others, CANNOT proceed unless __________.

• A. All stored energy is discharged
• B. The area is evacuated
• C. Lockout devices are installed
• D. All instruments calibrated

Answer: (A)

Discharging all stored energy is essential because energy can be held in springs, compressed air, hydraulic accumulators, charged capacitors, or other stored forms. If any of that energy remains when you isolate the system, a sudden release could occur and injure someone or damage equipment. By ensuring there is no residual energy, you create a true zero-energy state, which makes the subsequent lockout safer and prevents re-energization during maintenance. Evacuating the area, calibrating instruments, or simply applying locks don’t guarantee this zero-energy condition—the safety hinges on removing stored energy first, after which lockout devices can be applied to keep the system from re-energizing.