Lack of safe working practices, failure to wear personal protective equipment, and a live circuit breaker lead to electrocution in water treatment plant.
After a team of manufacturer service representatives perform maintenance on a motor pump assembly at a suburban water treatment facility, the plant manager calls in a licensed electrician to complete the "electrical details" of the job. After de-energizing the 480V circuit serving this pump, the service reps remove the damaged assembly and transfer a spare assembly into the housing of the unit under repair.
As they leave the room for a coffee break, the plant manager accompanies the electrician into the pump room where he is to "rack-in" the circuit breaker that will re-energize the circuit serving the repaired motor pump. (It was the policy of the water treatment facility to have one of its electricians on site when manufacturers perform any operational or maintenance procedure on any equipment.)
Just as the plant manager leaves the room to retrieve a pair of rubber gloves for the electrician, he sees a flash. He turns to see the electrician partially lying on the floor with the upper two-thirds of his body located inside the circuit breaker panel. The manager immediately calls 911. Although the local fire department and police are quick to respond, the electrician dies.
A short time later, two state electrical inspectors and an OSHA team arrive on the scene to investigate the accident. The plant retained our forensic engineering firm to evaluate the situation, determine what happened, and hopefully assign responsibility for the accident.
During follow-up interviews, the plant manager said he questioned the electrician on the whereabouts of his rubber gloves. The electrician said they were in his truck (although they were too small). Since the manager kept a spare pair in the emergency power room, he promptly went to retrieve them. Unfortunately, the electrician's choice to start his work rather than waiting for the appropriate personal protective equipment (PPE) created a deadly consequence.
The evening following the incident, an experienced electrical team dismantled Panel No. 4 where the electrician lost his life. Each individual wore 17kV-rated rubber gloves, hard hats with face shields, safety shoes, and other personal protective equipment. As they removed parts from the panel, the team found no signs of a tool or tools anywhere near the panel or in proximity to the location where the electrocution occurred.
A supervisor and two other electricians conducted an extensive inspection of the deceased's tools and tool belt. Since none of them had burn marks or any other damage, it was obvious a tool did not make contact with a live part. From this evidence, the OSHA team, state inspectors, and my staff concluded the electrician must have placed his unprotected hand inside the 480V control panel and his skin contacted an energized part.
A comprehensive inspection of the breaker revealed greater damage to the phase-B parts than the Phase-A parts. The damage to Phase-C components was greater than the damage to both of the others. The shade (an insulation barrier designed to cover certain live parts of the circuit breaker) was partially broken on the C phase side.
Before the incident, the electrician told the plant manager he intended to "do something inside the panel." We assume it was probably some type of a "make shift" repair of the shade. The shade probably acted as an obstacle that interfered with the re-racking of the breaker. (Note: The plant manager observed the broken shade before the electrician commenced his work. Therefore, the damage was not the result of the electrician's contact with a live part.)
The medical examiner determined the electrician died from "severe electrical shock." Similarly, the autopsy report identified an "abrasion of the right forearm." The abrasion on the right forearm was more than likely the point of contact with an energized bus.
Based on our investigation and evaluation, we concluded none of the manufacturer's service representatives or water treatment plant employees bore any blame for the death, notwithstanding the condition of the shade. Had the electrician used proper PPE, this accident would not have resulted in death.
During our investigation, the family of the deceased asked us to determine who owned the switchgear. We advised the attorney representing the family that this was a "legal" matter and not an "engineering" issue. If we determined the water treatment plant to be the owner, then the family might attempt to recover money beyond the limit workmen's compensation statue imposes. Similarly, if we found the owner to be a third party, then yet another litigation could result.
Sidebar: OSHA Violations
Investigators identified the following OSHA violations in this tragedy.
29 CFR 1910.132(d)(1): The employer did not perform a workplace assessment to determine if hazards were present or were likely to be present, which necessitate the use of personal protective equipment (PPE). The employer did not conduct an adequate workplace assessment in that (1) it failed to provide or require the use of a rubber mat to isolate employees from ground; and (2) it did not provide or require an employee to wear fire-retardant clothing while working around high-voltage equipment.
29 CFR 1910.132(f)(1): The employer did not provide training to each employee required to use PPE when necessary. Circumstances of this incident show the employer had not adequately trained electricians on the use of PPE when working on, or around, high-voltage equipment.
29 CFR 1910.147(c) (4) (i): Procedures were not developed, documented, and utilized for the control of potentially hazardous energy when employees are engaged in activities covered in this section. The employer failed to establish/document procedures for the control of potentially hazardous energy on all serviced equipment.
29 CFR 1910.335 (a) (1) (I): Employees working in areas where potential electrical hazards exist were not provided with, and/or did not use, electrical protective equipment for the work to be performed. The deceased employee did not wear PPE.