A Lockout/Tagout Failure Can Energize a Machine in an Instant
Verify zero energy before a hand ever goes inside
Failure to control hazardous energy is one of OSHA's most-cited standards and a leading cause of amputations, crush injuries, and electrocutions during servicing and maintenance. A machine that looks 'off' can still hold electrical, hydraulic, pneumatic, or stored mechanical energy. OSHA Scan analyzes job-site photos to flag energy-isolating devices that are unlocked, untagged, or bypassed before anyone reaches into the danger zone.
- A lockout/tagout failure is any situation where a machine or circuit is serviced without all energy sources isolated, locked, tagged, and verified at zero. It shows up as a disconnect switch left in the 'on' position, a breaker with no lock installed, a tag hanging without a physical lock, or a valve that was never bled of stored pressure before work began.
- In practice, these gaps appear when a technician makes a 'quick adjustment' without applying a personal lock, when multiple crews work on one machine but only one lock is set, or when a startup happens because no one confirmed the isolation point before re-energizing. Group tasks and shift changes are especially dangerous because a returning worker may assume the machine is still safe when a lock was quietly removed.
- The threat is invisible: a disconnect that appears open can still feed a control circuit, and a stopped conveyor can hold gravitational or spring energy. There is no warning sound before an unexpected startup, which is exactly why photo-based verification of every isolation point matters before hands enter the machine.
What is the difference between lockout and tagout?
Lockout uses a physical lock to hold an energy-isolating device in the safe position, while tagout uses a warning tag alone. OSHA prefers lockout because a tag is only a warning; tagout is permitted only when a device cannot accept a lock and equivalent protection is provided.
Does stopping or turning off a machine count as lockout?
No. Pressing stop or turning a control switch only pauses operation; the machine can be restarted. Lockout requires isolating each energy source at its disconnect, applying a physical lock, tagging it, and verifying zero energy before servicing.
Who is allowed to apply a lockout device?
Only authorized employees trained on the specific equipment and its energy-control procedure may apply locks and tags. Affected and other employees must be trained to recognize lockout and never remove or bypass someone else's lock.
How do you handle lockout when several workers service one machine?
Use group lockout: each authorized worker applies their own personal lock to a group lockout box or hasp. The machine cannot be re-energized until every worker removes their individual lock, so no one is left unprotected.