We just completed replacing tens of thousands of dollars in network hardware for a client who sustained a DIRECT lightning hit. It completely fried two Yagi antennas, two 50′ low-loss coax cables, two bridges, a Cisco 2600 series router, three 48-port Cisco switches, workstations, NIC cards, the smart jack for their T1 backup line, the phone closet air conditioner, the phone system, and some other hardware.
It appears lightning hit the ungrounded antenna mast, and arced through about 3/16″ of mastik and vinyl electrical tape where the antenna and the coax were joined and rode on the ground side of the coax. From there, everything went south. It caused the Cisco BR350 power injectors to literally blow their casings apart, which were sitting on top of a switch and a plastic bag. The bag was melted, and there are black outlines on the switch where the power injectors used to be. It also left black outlines on the otherwise white wall where the bridges were mounted.
Just remember – if you put up an antenna mast – ground the mast properly or at the very least, make sure it’s not the tallest structure around. Use a good 6′ or longer ground rod and don’t skimp on the heavy duty braided cable. Check your local electrical code, as it may specify minimum requirements for grounding.