When a machine's safety precautions fail, the operator is often put at risk. And when that happens, emergency stops can save lives.

Not long ago two electricians in an auto assembly plant entered a cell to check equipment on two robots. While they examined the equipment, one accidentally hit a limit switch, and one of the robots came to life. The robot pinned him between some equipment. His partner tried to hold onto the robot to keep it from striking him.

Luckily, two nearby employees heard the commotion and pressed the emergency stop button.

All moving parts represent potential dangers, but over many years government and industry have compiled a lengthy list of rules governing safety equipment. But sometimes rules aren't followed and accidents happen. The emergency stop can bail people out of dangerous situations.

Which is why emergency stops are necessary. According to the National Fire Protection Association's Standard, all industrial machines must have "a stop control that, when actuated, initiates immediate stopping control action of the machine tool."

Here's what to look for around your workstation.

Emergency stops should be located near the operators. That means in every location work can be done, both regular operation and maintenance. The stop button must be completely unobstructed.

In some workplaces, employers place barriers in front of an emergency stop device to prevent someone from accidentally bumping it. Demand that all guards be removed, because in an emergency situation, every second is critical.

A properly designed emergency stop halts all motion on a machine, no matter what mode it is running in. It should not rely on the machine's programmable logic controller to perform the safety function. Rather, it needs to drop power to all moving parts.

Emergency stops must be continuously operational, and they must also be periodically tested. For these tests, there must be an established protocol. And during the test, every device on a machine must be examined.

Of course, emergency stops are meant to be used in addition to other safety precautions, not instead of them. If your employer ignores other machine guarding, relying only on the emergency stops, then you are at risk. Emergency stops are not substitutes for other protections.

To find the complete standard governing emergency stops go to: www.nfpa.org

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