What is the main function of a lockout device in energy control procedures?

• A. To verify the zero energy state
• B. To physically prevent energization by locking out the energy source
• C. To store energy for later use
• D. To display a warning tag

Answer: (B)

The main function of a lockout device is to physically prevent energization by locking the energy source in the off or safe position. When maintenance is performed, a worker places the device on the disconnecting means (like a switch or valve) and secures it with a lock that only the worker can remove. This creates positive control over the energy source, so others cannot re-energize the equipment until that lock is removed by the person who applied it. In systems with multiple energy sources, each source gets its own lock to ensure complete isolation. While other steps in energy control procedures—such as verifying zero energy, managing stored energy, or using warning tags—are important, the lockout device’s primary purpose is to physically prevent energization.