What safety procedure prevents a machine from being started while someone is working on it?

• A. LOTO (Lock Out Tag Out)
• B. Lockout Only
• C. Tag Out
• D. Safety Shutdown

Answer: (A)

The main idea is to keep the machine from being energized while someone is working by isolating all energy sources and making that isolation permanent until the task is finished. Lock Out Tag Out achieves this by placing a physical lock on the energy-isolating device to prevent re-energizing, and attaching a tag that clearly states who is responsible and why the lock is in place. The combination of a lock and a tag provides both a tangible barrier and a clear warning, which is essential for safe maintenance.

Relying on a lock alone still prevents restart, but without a warning tag the situation may lack clear accountability and communication, which can lead to someone unknowingly re-energizing the machine. A tag alone warns but does not provide a physical barrier, so someone could potentially restore power. A safety shutdown is automatic protection that stops the machine, but it doesn’t establish a controlled, lockable isolation for ongoing maintenance or guarantee that the equipment remains isolated while work is done.