Loose bolts contributed to the collapse of 30 extra-high-voltage transmission towers as Hurricane Wilma moved across South Florida, an independent engineering analysis has determined. The October 2005 storm crippled Florida Power & Light Co.’s electrical system.
The 30 steel-pole H-frame structures on FPL’s Conservation-Corbett 500-kV transmission line between Palm Beach and Broward counties failed completely. Juno Beach, Fla.-based FPL retained KEMA Inc., a Dutch engineering firm, to investigate the performance of its electrical infrastructure during the storm. KEMA found that hand tightening of crossbrace connection bolts, a foundation failure resulting from faulty installation and one tensile failure together could have initiated a cascading affect bringing down the H-frames.