@gjacobse We have a tower beside our house that is isolated from the house to prevent a dual-ground situation.

All cables that run into the house are completely isolated to prevent anything jumping in.

We had a client in Edmonton that had a fax modem and a fax service running on a PC. When we set it up the POTS line was grounded prior to running into the PC. Somewhere along the way something was moved around and the POTS line in from the wall got plugged in to the PC modem directly.

An active storm had a strike against the pole in the alley and sure enough besides the boom scaring the carp out of folks the PC was dead. When we opened it up the controller chip on the modem was literally blown out as was the chipset chip under the heatsink. Time for a new PC!