Probability occurrence of estimated lightning surge current at lightning rod before and after installing dissipation array system (DAS)

Lightning surges in a telecommunication building were observed before and after installing a dissipation array system (DAS) for lightning in winter. A portable digitizing oscilloscope and a multichannel digitizing oscilloscope with an optical fiber system were used for the observation. The observed results from winter 1991 to winter 1996 show that the peak value occurrence probability at an antenna tower leg was not changed before and after installing the DAS and the occurrence at a pillar of the building was decreased a bit by installing the DAS. The peak value of the lightning current at the lightning rod of the building was estimated from the surges observed at the lightning rods, at a leg of each telecommunication tower, and at a building pillar. The occurrence calculated from this value was almost the same before and after installing the DAS