Printing plant employee is electrocuted after changing out 3-phase pump motor
Have you ever heard the expression, “green is ground the world around”? I have, many times. But do you ever personally check the green conductor to see if it actually is connected to ground — and is at ground potential? Unfortunately, an employee in a Florida print shop did not — a decision that ultimately led to his death.
As retailers in the United States and around the world continue to recall thousands — if not millions — of toys, tubes of toothpaste, and other miscellaneous products manufactured in China, I am reminded of this particular case — a case that involved electrically powered printing equipment also manufactured in China. The equipment installed in the print shop did not display a UL or similar label; nor was it inspected or installed by a licensed electrician. When an original Chinese pump motor failed and was replaced with a motor manufactured to U.S. standards, the stage was set for serious injury or death. As this case will demonstrate, what you don't know can kill you.
The site of the electrocution was a small specialty print shop. The accident occurred when the owner of the business and two other employees were adjusting what's called a “glazing machine” or ultraviolet coater.
Depositions, statements, and police reports taken after the incident indicated that the owner and one employee were working on one side of the machine while the victim was working on the other. Attempting to clear a paper jam — or possibly make some other type of adjustment — the group was working in the area of the machine where coating solution was applied to the paper. During this process, the victim suddenly called out and then fell silent. When the owner walked around the equipment to check on his employee, the victim was non-responsive, appearing to have caught his arm in the machine. Although the owner immediately disconnected the electric supply to the machine in an effort to free the man's arm, the victim slumped to the floor.
Emergency medical services quickly responded, attempting to resuscitate the worker, and transported him to a local emergency room — where he was pronounced dead by the E.R. physician. According to the medical examiner, the cause of death was electrocution.
The estate of the deceased filed suit against the company that manufactured the printing equipment and the company that imported the printing equipment from overseas. In that lawsuit, the plaintiff alleged (among other things) that the suspect printing equipment was defective — and that the defendants (the importer and the manufacturer) knew, or should have known, that the equipment was defective and a potential source of lethal electrical current. The plaintiff's employer, the print shop, was not named in the lawsuit.
I was called as an expert witness by the importer's counsel to analyze the forensic evidence.
Because I became involved in the case some time after the date of loss, it just so happened that the print shop had gone out of business, the site had been re-let, the new tenant had remodeled the space, and a creditor had repossessed the equipment in question; therefore, it could not be located. Given the situation, my task was to reconstruct the accident from the historical evidence and advise counsel on my conclusions.
I quickly learned several issues of importance were not in dispute or were quickly confirmed. Invoices clearly showed that the print shop where the deceased was working had purchased the ultraviolet coater from the defendants. The owner of the print shop had seen a similar ultraviolet coater, of European manufacture, at a trade show and subsequently heard that a “Chinese copy” of the ultraviolet coater could be purchased at a significant savings. Next, he located, purchased, and imported the ultraviolet coater from a Chinese manufacturer through an importer in Florida and an agent in California.
The chain of possession of the ultraviolet coater started with the manufacturer, continued through the manufacturer's agent in California, then through the importer in Florida (the company I was helping defend), and finally ended with the print shop. The installation took place with the assistance of Chinese nationals, employed by the manufacturer's agent, who reportedly spoke little (if any) English. Furthermore, the manuals that came with the equipment had only a title page in English; the balance of the document was in Chinese. There was also no evidence that a licensed electrician performed the installation.
My investigative efforts also uncovered some red flags relating to service issues with the ultraviolet coater. Some items were replaced or repaired under warranty. However, as the ultraviolet coater continued to fail to meet expectations, factory support slowed and then stopped.
After a small 3-phase pump motor failed, the stage was set for impending danger. The motor and pump powered a reservoir that stored the glazing or ultraviolet coating solution. Little was known about the motor, as it contained no manufacturer's label or similar information. Usage would have indicated that the pump was wired for 230V, 3-phase, 60 Hz. Size would have indicated that it had a fractional horsepower output.
The solution was pumped out of the reservoir to charge the ultraviolet coater and then returned to the reservoir after use. Although connected as an integral part of the ultraviolet coater, the reservoir was actually a separate metal tank, with the pump and motor mounted on top. It was connected to the balance of the ultraviolet coater by an electrical service cord and a rubber hose. In what was apparently a money-saving effort, the owner located and obtained a replacement pump motor from a local supplier to solve the problem, and the deceased installed it himself.
The deceased was described in depositions and reports as an experienced pressman. Nothing was noted, however, that indicated he was experienced in the troubleshooting and replacement of 3-phase motors. More to the point, the deceased was reported to have warned his fellow workers to be careful of the repaired reservoir, as it was producing electrical “shocks” — apparently without realizing the underlying danger. This action (the repair of the reservoir) produced the only piece of physical evidence I was able to inspect — the original failed pump motor had been saved. The junction box of the original motor, showing wire connection lugs, is shown in Photo 1.
Another illuminating piece of evidence I discovered was a report from a local electrician who was hired by the owner of the print shop after the electrocution to make an onsite inspection. Possessing excellent credentials, the electrician had been licensed and active in the trade for many years. He was retained as an expert witness by the plaintiff's attorney.
In his report, the electrician maintained that the reservoir was energized relative to ground and sitting on sheets of cardboard, which effectively isolated it from earth contact and ground. He also noted that the electrical service cord between the control panel of the ultraviolet coater and the reservoir contained three insulated conductors colored black, red, and green (Photo 2). The replacement pump motor contained four conductors (black, red, white, and green). At the time of his inspection, the supply conductors and motor conductors were connected black to black, red to red, and green to green and white — an arrangement that proved to be fatal (click here to see Figure).
A review of police reports and photographic evidence indicated that the deceased was found in a position between (and in close proximity to) the ultraviolet coater and the previously described reservoir. As part of my investigation, I located an exemplar ultraviolet coater in use at another location, making arrangements to visit the site to inspect and photograph the equipment. Although the exemplar was identical to the subject equipment, it had been rewired by its owner. Much of the original wiring harness was abandoned in place, so the exemplar was similar enough to confirm the physical parameters of the accident scene. The owners were able to relate in considerable detail what they had found in the original electrical wiring as well as what changes had been made to their equipment. I was able to locate, confirm, and photograph the original supply cord between the control panel and the reservoir pump motor.
I also inspected and photographed the original pump and motor. The original had been saved after it was replaced prior to the electrocution. As you can see in Photo 1, the wiring connections in the pump motor housing were indeed colored; however, the colors did not include green. A separate threaded hole was provided for a grounding screw, but I observed no scratches or similar evidence to indicate it had ever been used.
Based on my investigation, I offered the following conclusions. The deceased was electrocuted by electrical current flowing from the energized reservoir to the grounded ultraviolet coater frame. The ultraviolet coater was wired for (and connected to) a nominal 3-phase, 230V electric supply. The wiring error in the connection of the replacement pump motor had energized the housing of the pump motor, pump, and reservoir with phase voltage relative to earth ground. The position of the deceased allowed for simultaneous contact with the metallic reservoir and the grounded frame of the ultraviolet coater. The current path was through the body core.
The deceased, who was neither experienced in this type of work nor a licensed electrician, created the danger when he replaced and mis-wired the pump motor on the reservoir. However, the use of a green insulated conductor as a phase conductor could have fooled even an experienced electrician.
A settlement was reached for an undisclosed amount prior to the case going to trial.
There are several lessons to be learned from this tragic accident. First of all, if you don't know what you're doing, leave well enough alone.
The pump motor was replaced without the benefit of an experienced electrician. For the deceased (the pressman who replaced the pump motor), this was a fatal lesson. Although he expected the green wire to be ground, he clearly did not have the experience to understand the relationship between the number of conductors in the cord and the requirements of a 3-phase pump motor.
The equipment involved was imported from China at a significant savings over comparable equipment from Europe. I have investigated a number of electrical incidents that related to electrical goods manufactured in China. In some of those cases, as in this case, there was no evidence of a UL or similar tag. In some cases, there was a UL tag; however, the tag was counterfeit. In this case, absent a UL or similar label, an inspection should have been made of the equipment, once it reached the United States to determine if it was safe and appropriate for its intended use. The owner failed to have such an inspection and relied entirely on the manufacturer.
The equipment was installed without the benefit of a licensed electrician as required by local and state codes. Although the use of a licensed installer would not have prevented this death, the installer might have noticed the non-standard use of color coding, coupled with the lack of grounds, and warned the owner. Nevertheless, it would have been up to the owner to bear the expense of re-wiring the equipment — a cost he would likely have been unwilling or unable to bear.
Falany is a registered professional engineer and certified electrical contractor in the state of Florida. He is an expert witness and forensic investigator with FORCON International Corp., Brandon, Fla.