I'm EXTREMELY familiar with lightning abatement, but I appreciate the links. I don't know what the last event was at the Church. It does not have a steeple, but does have the usual high slope roof.
This last event took out our: Fire Alarm (required replacement external power supply for horn/strobe synchronization) The fire alarm itself and all the remote sensors, horns, etc... were fine. The PBX (a real no-name POS, but it works.). That just needed a reset. Security Panel (blew the power supply fuse - this is a separate system from fire alarm) One Newmark dual CD player. And finally, the Strand Model 300 Theatrical light controller. And I think that's it.
Because my license would not cover me, I chose NOT to attempt repairs to the Fire Alarm system, but it was pretty obvious what was wrong with it - once you wiped the soot away. It's a Kiddie system and I probably couldn't get parts anyway?
The PBX was not grounded, and apparently had never been since the day it was installed. (?) Also, no additional protection other than whatever's outside at the Telco.
The Strand is a longer story. It had been baked a couple times before. 1 Channel DMX512 was DOA long time ago. Before my time. Dimmer packs in the back room (48 of them at 2KW each) never seem to have a problem. The RS485 comm-link is another story. Twice that I know of, it blew out the LTC485 transceiver chips back at the dimmer paks. This IC sits in the middle of the board and litterally gets its top blown off (cracked, etc..) Very obvious repair - and luckily Strand did put these in 8-pin DIP sockets. (A clear indication of high failure rate item??) Fine traces on underside of board don't seem to be bothered... (which is a bit curious?)
Back on the other end (control room), the Strand 300 is basically a PC outfitted with some special software an a DMX512 (XLR-type) daughterboard to do the RS485 conversion. This is what went out this last time. (There are only 2 channels on this board, and as I mentioned previously, 1 was previously DOA.) The PC portion was fine, but no DMX output. The daughter board "looked" fine and everything you could visually ID metered OK. I suspect the problem was on the protection parts, but no schematic or parts availability so it had to go back to Strand this time. All fixed now, and at least we have BOTH channels restored.
The grounds look really good. Ditto for power. It's clear the comm-link is the weak link but I honestly don't have a good handle on how lightning is getting into this. It is twisted pair (looks to be 16 or 18 guage. Run is about 150 feet or so. In metal rigid conduit all the way - some of which is outdoors.
About the only thing I can think of is the cable is damaged mid-way in the conduit. But if I pull this out I'm just going to switch to fiber optic and be done with it.
I do have plans to check the grounding for the entire building... This is Florida so the soil is s^it. I use the term "soil" loosely. I should have said "sand". I suspect this last strike was close enough to put a fault current in the earth, given the extent of the damage. Oh, I forgot to mention it also char-broiled an 115-volt outlet that was running a window shaker air-conditioner. (AC is fine) Some of our neighbors also had reported damage.
The Church is old enough (and unfortunate enough?) to have crappy Zinsco breakers, but of course that's not the problem other than they cost an arm and a leg. But hey, God will provide....
By the way Guy, Martin Uman was one of my professors in college. Very sharp when it comes to lightning. Half of what I know about it I learned from him. He's got some really excellent texts out there if ever get your hands on one.
Your comments about the existance / condition of the lightning rods warrants further investigation. My "work" there is free (as in volunteering) so I don't normally dig too deep into what-ifs. (present situation excepted) I don't recall seeing rods, but there may be some, and if poorly grounded -- well then, that's not helping much!
-mpm