U.S. Department of Labor

Mine Safety and Health Administration Industrial Park Road RR1, Box 251 Triadelphia, West Virginia 26059

December 13, 1999

MEMORANDUM FOR  LEE D. RATLIFF
                                  Assistant District Manager, North Central District
                                  Metal and NonMetal Mine Safety and Health

FROM:                       ARLIE B. MASSEY
                                  Electrical Engineer

SUBJECT:                  Executive Summary of Testing of Busbar from Kaiser 
                                  Aluminum And Chemical Company's Gramercy Plant

A series of eight dielectric tests were conducted on the phase "A" busbar that was removed from the Auxiliary Cabinet of Switch House No. 2 at Kaiser Aluminum And Chemical Company's Gramercy Plant. This busbar was involved in the phase to ground fault that occurred at approximately 4:43am on July 5, 1999. The busbar has two identifying numbers, PS-1 and PE 28. The purpose of the tests was to determine whether the busbar was effectively insulated for 13,800 volt system voltage. A total of eight tests were performed on the busbar at locations where the insulation was not damaged by the electrical fault. Each dielectric test was conducted by applying approximately 15,000 volts between the metallic bar and the outer surface of the insulation. The voltage was increased from approximately zero volts to approximately 15,000 volts at approximately 500 volts per second and maintained for approximately one minute.