Working on a residential pool project, a young laborer loses his life after trying to force a 120V plug into a 240V receptacle while standing in water.
When the construction crew came to work one morning on a residential project, they discovered the tragic scene: an 18-yr-old laborer lying in a puddle of water at one end of an emptied 50-ft-long swimming pool. At this point, no one knew much about the victim, except that he was new to the job and probably didn't have much experience. To help uncover the events leading up to this fatal electrical accident, the insurance company hired our forensic engineering firm to search for answers.
It all started when the new owner of this $2-million house embarked on a rehabilitation project for the house and grounds. When construction reached the final cleanup stage, the pool contractor completed his final washdown on the replastered pool, leaving a 1-ft puddle of water.
Based on interviews with the superintendent and other workers, we began to unravel the unfortunate steps the victim took. Late in the day, the foreman asked him to pick up a sump pump (left in the yard by the pool contractor) and pump out the remaining 1-ft puddle in the pool. Characterized by coworkers as conscientious, the young worker followed these instructions, after everyone left the job site.
The events that followed are inferred, based on the young worker's task at hand. First, he must have picked up an extension cord lying on the patio (the tile c ontractor used this heavy-duty cord to power a tile saw). Next, he plugged it into a 2-pole, 3-wire, grounded 30A, twist-lock type, 240V gang box lying nearby. He'd seen the tile setter use this gang box for his big saw. The worker then pulled this extension cord over the side of the pool and attempted to plug the 2-pole, 3-wire, 120V standard male plug (at the end of the sump pump's 10-ft extension cord) into the receptacle placed at the end of the heavy-duty extension line. At this point, he ran into an obstacle. Since the sump pump's cord had straight blades at the end, it wouldn't fit into the receptacle. This is where he got into trouble.
While standing in the puddle, he attempted to force the 2-pole, 120V male plug into the power cord's 240V female receptacle. Although it's not clear how he got the spades to enter the 240V receptacle, he had pliers in his back pocket. We surmised he bent the blades and put the pliers in his pocket, before attempting to make the connection. At the moment of contact, we assume there was a connection between the plug and receptacle (one or both probably wet), his wet hands, his body, and the puddle. The resulting power flow through his body caused burns on his hands and legs and was enough to cause his muscles to freeze and his heart to stop.
Upon further inspection, we found the power supplied to the site came from a temporary 4 in. by 4 in. power pole, with a 200A fused disconnect switch. This switch fed three other gang boxes strung throughout the site via 4-conductor waterproof cords. The conductors of each cord connected to the disconnect switch with lugs held in place by screws taped into each bus inside the switch. There was no separate fusing of the individual circuits at the switch, nor were there fuses in the gang boxes. Of the 200A fuses at the disconnect switch, one was blown, thus opening the involved circuit.
Since this incident occurred some time ago, prior to the rigorous inspection procedures followed today, such a jerry-rigged electrical arrangement would not meet today's safety standards or accepted practices used by careful electricians. Although we may become irritated at all of the National Electrical Code, OSHA standards, and inspections mandated by current-day construction and building requirements, this case is a good reminder of the importance of such requirements.
This accident clearly resulted from a combination of unfortunate circumstances. First of all, the worker should have received some training regarding the voltages and usage of the available cables and potential dangers of working with electric power in the vicinity of water. Similarly, had someone familiar with the basics of electrical installation and/or pool construction been present, this tragic accident may not have occurred.
This case proves characteristic of many forensic engineering investigations: Accidents are seldom the result of a single action. Rather, they're the combination of unfortunate, simultaneous events. This case ended with the insurance carrier that hired us paying damages on behalf of the general contractor.
Garrett is the chief executive officer for Garrett Engineers, Inc. in Long Beach, Calif.