Energy Isolation: Why Lockout/Tagout Saves Lives

Machines don't know you're inside them. A conveyor, mixer or press will start the moment someone flips the switch, and that someone may be on the other side of the building with no idea you've climbed in to clear a jam. Electricity isn't the only danger, either. Hydraulic pressure, compressed air, springs, gravity and stored heat can all move parts or release energy long after the power is "off."

The rule is easy to remember: isolate, lock, tag and verify before you put any part of yourself in harm's way.

What that looks like on the job

• Identify every energy source. Electrical, hydraulic, pneumatic, mechanical, thermal and chemical. Many machines have more than one.
• Isolate at the source. A stop button or a control switch is not an isolation.
• Apply your own lock and tag. If several people are working, each person applies their own lock, usually on a group lock box. You hold your key, so nobody can restart the machine while you're inside it.
• Release stored energy. Bleed pressure, block or lower raised parts, and let things cool down.
• Verify before you start work. Attempt a start where it is safe and appropriate, and confirm that every hazardous energy source is isolated or controlled using the verification method required for that equipment. If anything moves or reads live, stop and find out why.

Real-World Impact

The story behind many lockout fatalities is painfully similar: a worker reaches into a machine to clear a jam or make a quick adjustment, relying on a stop button or on a colleague's assurance that it's off, and someone restarts it. OSHA estimates that compliance with its lockout/tagout standard prevents around 120 deaths and 50,000 injuries every year in the United States. That is an estimate of lives saved by good practice, not a count of deaths, but it shows how much this one rule matters.

Source: U.S. Occupational Safety and Health Administration (OSHA), Control of Hazardous Energy

Reflective Questions

• Have you ever let someone else's lock, or someone's word, stand in for your own?
• Which machines on our site have a hidden energy source that's easy to forget?
• Do we always verify isolation before work starts, or do we skip it when we're confident?