Two Human Errors Can Defeat a Lockout

We investigated a lockout gone afoul. A maintenance mechanic was interfacing with machinery. He was performing a repair. He set up a lockout for the repair. However, a ground fault involving a 480-V branch circuit still occurred.

The company had a written hazardous energy control process. This husband, father, and grandfather was trained and authorized for hazardous energy control. He had completed several hundred lockouts over 20-years without incident. The mechanic’s annual re-certification was current. He was known to work safely.

The facility has a machine-specific Energy Control Procedure. He followed it. We found the locks on isolation points. The keys were in a group lock box. His lock was on the lock box. His key was found in his toolbox.

Yet, he was still shocked.


Two Errors Occurred

The first error was isolating the wrong disconnect. This facility had numerous multi-stage machines and appliances in a congested area. The machinery had been installed, upgraded, modified, and rebuilt over the years. We counted 17 electrical disconnects within 10 ft. of the machinery footprint. None of the disconnects were labeled. This mechanic opened a circuit and isolated it with a lock and identification tag. The target machine was still energized.

The second error was failing to verify zero energy state. The mechanic or a second person did not press the machine actuator to verify zero energy state. He assumed that the lockout was applied properly. The at-risk behavior of short-cutting the energy control procedure nearly killed him.


Preventing These Errors

These errors are quite common. We’ve seen these errors in multiple cases. When we lead the SafeTask® Lockout course, we teach authorized how to prevent these errors.

A work station can be confusing when it has multiple machines.  A simple control that significantly improves the safety margin for a lockout task is to label all of the isolation points. An isolation point is a gate that stops the flow of energy. Your isolation points referenced in energy control procedures should be labeled with unique alpha-numeric addresses. This means that is each isolation point receives a label with an identifier. And, no two identifiers are the same. While this control is not required by the OSHA or ANSI standards, it is a critical.

Another simple human factors improvement is to cross reference the unique alpha-numeric addresses in your energy control procedures.  This improvement further avoids the error of isolating the wrong energy source. Had the 17 electrical disconnects been labeled and cross reference, the maintenance mechanic could have applied the lockout to the correct isolation point or gate. This incident was preventable.

Risk-taking during lockouts is still all too common. A simple safe behavior can significantly improve the safety margin during a lockout. Establish in your lockout practice that a second person, other than the person who set up the lockout, verifies zero energy state for lockout tasks along with the authorized person performing the  task. Most of our SafeTask® users take this extra precaution for complex lockouts.

Another way to reduce risk-taking is to teach a skill set to perform lockouts. When we reviewed this company’s training process, the lockout training was heavily focused on memorizing OSHA compliance details. The training process did not teach a skill set nor the task flow for lockout.

These improvements can avoid common errors during lockout tasks. Come to our SafeTask® Lockout course for authorized persons and we can show you how to improve the rate of safe behaviors during lockouts.

About Bryan Raughley

Bryan’s expertise is safety supervision, behavior-based safety, and safety management systems. He works with all levels of an organization by applying the SafeTask® System to implement solutions, making work tasks safer.