After an electrician dies in an arc flash, the investigation reveals that negligence on the part of management is to blame
When an electrician at a Cleveland industrial plant got the call to rectify a work stoppage situation by replacing a blown 480V fuse, he was unaware of the one thing management should have told him but failed to: Not only did the system he was about to work on include parts that were more than 60 years old, it had been modified in such a way that almost guaranteed disaster. As he stood on a man lift and replaced the fuse in an obsolete and defective bus plug in a ceiling-mounted 480V bus duct, an arc flash erupted from the duct, engulfing him in flames and igniting his clothing. Although the flash only lasted a few seconds, that was long enough for him to suffer extensive burns that would kill him days later.
The attorney acting on behalf of the electrician's family discussed this accident with me to determine if a case could be brought against the electrician's employer. To be successful, such a case would require the attorney to prove willful negligence on the part of the employer. After looking at pictures of the damage done to the bus plug, I agreed to review the facts. I discovered that the next upstream circuit breaker was installed in 1941, but more troubling was the fact that it had been blocked in the closed position. I decided the case should be investigated.
Investigating the claim.
Before the arc flash occurred, the electrician had been attempting to install a cartridge fuse in a bus plug that was as old as the circuit breaker (Photo 1 above). He had been instructed to replace this fuse as soon as possible because it served a lighting circuit that had gone down and left a portion of the plant in the dark, which made it impossible for some plant workers to do their jobs.
The 3-phase bus plug energized a single-phase lighting load and was mounted on the underside of a 480V busway. The electrician encountered a phase-to-phase fault when one of the line-side fuse clips in this very old device bent over and made contact with an adjacent fuse clip. The upstream breaker was a 600A air circuit breaker also manufactured in 1941. This breaker had an external lever that opened the contacts. However, the lever had been held in the closed position with a block of wood (Photo 2 at right). I later determined that this had been done more than two decades earlier to prevent nuisance tripping. A 1,600A main circuit breaker, which was the next unit upstream, cleared the fault. If the 52-year-old 600A breaker hadn't been blocked and had been operating correctly, the fault would have cleared in less than 10 cycles, or 0.167 sec. This would have most likely reduced the fault energy to a level that would have allowed the electrician to survive. Shortly after the electrician's death, the plant installed a new breaker to replace the old unit.
Because the 600A breaker was blocked, the 1,600A breaker took almost 7 sec to clear the resulting line-to-line fault. However, examination of the bus plug showed that the initial line-to-line fault progressed to a 3-phase fault. The 1,600A breaker tripped within two cycles of the development of the 3-phase fault. Eyewitness testimony stated the fault lasted a long time.
At the conclusion of my investigation, I presented the attorney with a preliminary report that included the following findings:
Management purposely blocked the 600A circuit breaker in the closed position, which prevented it from tripping.
Management was irresponsible in the continued use of excessively aged and obsolete equipment on the 480V system, existing open conduits, and enclosures with exposed wiring.
Management allowed for inadequate documentation of the existing electrical system and instituted an inadequate lock-out/tag-out process.
Blocking the circuit breaker closed was a very serious safety violation. In fact, the resulting accident led to several OSHA fines and violations. How could a major plant operate for so long in this condition? I found that this condition was brought to management's attention in the mid-'80s when a forklift damaged the 480V busway and caused a fault that didn't immediately clear. No one was injured as a result of the fault, but the bus way incurred significant damage. The 600A circuit breaker was located on a platform in the ceiling about 100 ft away — not a convenient location.
In preparation for my testimony and the preliminary incident report, I discovered that management had testified in a deposition that it had developed a lock-out/tag-out procedure. I was anxious to review it.
During my deposition, the defendant's attorneys focused on two issues. The first was whether the electrician was following safe work practices. No one knew exactly what the electrician did as he was changing the fuse. However, he did use fuse pullers and was forced to replace the fuses hot because de-energizing the bus would have shut down a large area. Given these conditions and the fact that he wasn't electrocuted, it was difficult to lay any blame on him for what happened.
The defendant's attorney also tried to determine whether failure of the 600A circuit breaker actually caused the fatality. I went through the process of determining the available fault current from the utility and the calculations of available fault current at the failed bus plug. There was the impedance of the plant transformer, 1,600A bus, 600A cable, and the 480V bus way. The available fault current for a line-to-line fault at the bus plug fell just under the near-instantaneous trip level of the 1,600A circuit breaker. The results of my calculations matched the eyewitness accounts. I strongly recommended that all equipment installed more than 30 years ago should be tested and a condition assessment performed. It was my opinion that the plant's workers were still at risk of injury from the remaining obsolete equipment. It appeared that this electrician did everything he could reasonably do; management just exposed him to an unnecessary risk of danger. His only safe option was to refuse to do the work, which would have put his job in jeopardy.
However, I never had the opportunity to testify in court. The plant's owners settled with the deceased's estate for a significant amount. The attorney advised me that management feared a jury trial. Unfortunately, resolving the matter out of court prevented anyone from addressing the remaining issues, namely the obsolete electrical system and the questionable lock-out/tag-out procedures. And if management has any intention of continuing to require its workers to work hot, those are two problems that can't be ignored.
Hernandez is the president of Powerserve Technologies, Inc. in Riviera Beach, Fla.