The real question to ask when an interlock is bypassed

What’s the first question you ask when you find an injury or near miss situation where an interlock or other safeguarding device was bypassed? Do you ask why the employee bypassed the safeguard – or do you ask what is it about the task that required bypassing? This is a subtle but significant difference.

The first approach usually leads to an immediate discussion of the hazards and chastising the employee for the bypass. I’ll explain why that approach is often flawed.

I recently investigated an accident where an interlock into a robot cell had been intentionally defeated. An employee went into the cell to master a fixture and the robot activated, thankfully causing only a minor injury. The maintenance worker who performed the bypass was beside himself with guilt. I asked if the task could be done without power. The answer was, “No.” Mastering the fixture required power, but the cell had been designed to eliminate all power if someone went through the interlocked door.

A combination of using thinking based upon Task Based Risk Assessment (TaBRA) and a rudimentary understanding of machinery opens our eyes to the fact that the cell was improperly designed. If the employees don’t defeat the safeguard, the plant cannot run. How’s that for an eye-opener?

Avoiding the simplistic approach

Just this past week, I returned from another client where we are working on lockout-tagout and using TaBRA. The safety manager went over to a new machine being commissioned by a skilled worker. In this case, the interlock had not been activated to put the machine in a state where there would be no motion. After a few minutes of listening to the exchange, I asked the worker, “Do you need power to do your work?” He looked at me quizzically and replied, “Of course, I’m doing troubleshooting trying to get the machine running.”

There were indeed hazards, but the simplistic approach of thinking a safeguard designed to protect an operator could afford proper protection for this worker doing this task is flawed thinking. Critical thinking involving the worker, engineering and safety is needed to address such a situation.

If you find that your workers are bypassing safeguards and your continued efforts to correct the problem are not yielding results, you might ask, “Does the task you are doing require power?” If not, you have a shortcut and should act accordingly. If the answer is “Yes,” you need to find suitable safeguarding and methods to allow the work to be done safely.