Shortcuts in safety and incorrect wiring lead to severe injury in manufacturing plant. How did this happen, and who is at fault?
An accident was bound to happen. For some time, both production lines at a manufacturing/packing facility were operating at full capacity. And as business grew, overtime became a necessity. Due to extended hours of operation, a piece of equipment, associated with the conveyor system of Line B, developed problems. The entire production line backed up, causing products to cascade off the conveyor.
Called in to fix the problem, a maintenance worker positioned the system's motor controller in the OFF position, to adjust a particular gearbox. With his hand inside the gearbox, he asked a fellow worker (standing on the other side of the conveyor) to hand him a screwdriver. Leaning forward, the fellow worker's body hit the ON button, energizing the machinery.
As the worker's hand became entangled in the machinery, others rushed to shut off the power. One tried turning off the same motor controller that was accidentally turned on, but he wasn't fast enough. The small OFF button was inside a recessed guard!
During this delay, other workers ran to what they thought was the "main switch," which was more than 12 ft away. When they tried to shut off the so-called "main switch," which served both production lines (A and B), they discovered conveyer Line B would not shut off. (Later, our forensic engineers learned the power to feed all of the equipment on Line B was from the line side of the "main switch," feeding the original production Line A.)
As the workers realized what was happening, one used a screwdriver to depress the small OFF button on the motor controller. By this time, the maintenance worker was in horrible pain. He suffered a crushed hand and severed appendages.
Correspondingly, a national insurer retained our firm to conduct an investigation of the circumstances leading up to the injury of the factory worker.
In the course of our investigation, we discovered the vendor who sold the manufacturer the equipment contained in Line B had also wired the equipment. Because the "main switch" was not readily accessible, and more importantly, it waswired incorrectly, the maintenance worker had the legal right to look beyond the workman's compensation laws that protected his employer and seek remedy from the third party who was responsible.
After some time, we conducted a follow-up analysis/report on behalf of the injured workman. Our original client authorized and encouraged us to provide that service. (In case of a recovery from a third party, the workman's compensation insurer frequently recovers some costs.)
In our report, we note the ON switch should be the small button housed in the recessed protector, to require a deliberate effort to energize the machine. The OFF switch is more appropriately a large "mushroom" red push button, to shut the machine off with a minimum time delay.
Our report reveals that due to faulty wiring, a poorly placed main switch, and unacceptable ON/OFF switches, workers could not turn off the affected machinery in the shortest time possible.
NEC Sec. 430-107 requires that one of the disconnecting means "shall be readily accessible." The term "should" in the NEC is an advisory word. However, the term "shall" is mandatory. Article 100 defines "Readily accessible" as "Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc."
Continuing with the report, we analyzed the recommended use of lockout/tagout procedures. Workers frequently use this procedure when working on equipment that, if operated, could cause physical injury or damage to equipment. In this case, the maintenance worker needed power to the gearbox to complete his adjustments. Although this case is still active, everyone involved can learn from it. Inspect any equipment you or outside vendors install or repair in your facility. Take time to make sure installations comply with all codes and standards. And, never forget safety when working with machinery.
From time to time, it's wise to refocus on the intention of the National Electrical Code, as articulated in Sec. 90-1(a) "Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity."
As the industry engineer and later the maintenance crews who modify the production operation blend the diversity of energy in use and manufacturing equipment, important safety features are often omitted. OSHA works to prevent the lack of safety procedures. Even with this agency in operation, people tend to overlook essential safety precautions. You must review all aspects of your operations to prevent accidents. Do this now, not tomorrow! Recognize the wisdom inherent when complying with safety codes and standards.