Electrical Hazard -- Billboard

It was the first time that JQ had been assigned to put up a billboard without supervision. When they found him on the billboard's catwalk, he was dead.

There were burn marks on the aluminum ladder, on the sign, and a nearby power line was down.

 

It was clear that JQ was electrocuted when his ladder made contact with the power line.
By the time I was called in to conduct an investigation, the aluminum ladder had been misplaced and the power lines had been moved so as to be further from the billboard.
The findings of an earlier investigation concluded that JQ was probably lifting the ladder to move it to another location when he lost control of it and it fell backwards onto the power line.
HF Investigation and Analysis: An accurate 3D computer model was created of the billboard, the ladder, and of a figure representing JQ. The locations of the burn marks on the sign, on the ladder, and on JQ were positioned on the model. The various components of the model were systematically manipulated in an attempt to account for the observed pattern of burn marks and JQ's final rest position on the catwalk.
The conclusion of the previous investigation was not supported. The location of the burn marks did not support that JQ lost control of the ladder and that it fell backwards. Rather, more likely than not, JQ was rotating the ladder so that he could use it to climb down from the billboard, which was the standard procedure.
The accident might not have occurred if the power line had been a few feet further away from the billboard. (Clearly, aluminum ladders should not be used in the vicinity of power lines.)
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G. David Sloan, Inc., 1999, www.gdsloan.com, Olympia, WA, USA

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