sooooo now that I got my DT computer back up and running (Thanks SOCAL for all the help and ideas) , I got a new "Electronic" Fubar/flailex for you'all to ponder , last week  the complex maintenace dude gets on the roof of my Stran steel building to fix my night time Merc vapor lites , I have multiple surveilance cams mounted to the inside and outside of said building the "insides" are on dry wall the "out sides" on the steel (and the Cam bodies show "continuity" to ground thru the "S" vid coax ,I tested ) . I'm sitting at my desk actually watching "Mr Maintenance" as hes messing with the cover plate on the junction box for the lites (bad wire nut coonection and "BOOM" all my outside cams "go dark" , WTF mind you all the outside cams are directly screwed to the STEEL building HMMMM we systematicallly test and find all the outside cams are "ZAPPED" ,bad , failed , Ph*cked up,  Well $1000.00 bucks worth of new cams later we up again  I'm wondering ? What could have actually happened ?? I say he was fixing the 110 lites without the breaker off "arched a wire" and sent 110 "Bullet" to ground "spiking" my very sensitve Video Cams No other plausible explanation for 4 simultaneos outside Camera failures ?? Who wants to tackle this ?? I say they should reimburse me any thoughts ? I trust you guys judgment ! Tom

GT the Cams are 12v DC power thru the CPU on the "Survey" system  tom

Coincidence ?? 

probably not a coincidence tom. if he was working a hot circuit and he arced it against any of the building metal at all then that would cause an arc to your camera`s through the building steel and yes would wipe out your cams. do like Gt suggested and have them tested. they will be able to tell you more. but from what you have said that is what it sounds like he did. 
i would have them tested and see what the report says and if they were arced i would say try and have the company he worked for reimburse you. course that could be more trouble then it is worth also. good luck

X3   Do you have video recordings of the mishap?, Scare them into reimbersment 

Tom, you say the cameras are grounded through the "S" vid., but what about the body?, if not grounded, the camera is isolated, the problem is, if there ever was a lightning strike, you could be a dead man....the charge would go through the "S" cable and not to the building to ground...in other words, you would be the path of least resistance (unlike what Josh thinks LOL)..

GT

Guys I'm goin to the landlord today for a "pow wow" I know all the outside cams are dead , what I was meaning was that the camera bodies have some direct connection to the building (intended or not) in other words the possibility does exist for voltage to go directly back into the cmas from such an event (lightning too I suppose) Tom

My guess, the building is using a neutral to ground system, Tom. Pretty standard west coast stuff. And from what I read, the cams are 12 volt. IMO, the cams were prolly fine, and just the power supply/controller was affected. Could be wrong. The main thing that happened was that obviously, the dipshit didn't turn off any breakers before doing any of this. A big no no for obvious reason one, but reason two is depending on how much demand was on that same circuit at that time, he successfully sent a huge voltage spike throughout the complex. Tossing a breaker off then on tends to minimize this. Because of the neutral to ground system, your neutral wire can, and will, carry voltage if the hot wires are disconnected or start to have a poor connection. Stick your finger in either side of an electrical outlet and tell me which one shocks you.  The safety feature of neutral to ground is you're not likely to get electrocuted because it's connected to an approved ground anyway. Makes sense.

This is also why you turn off the goddamn breaker. Stored energy in the neutral wire, and worse should the physical ground of the system not be up to par, then connect the hot wires back again, alll that stored energy flows clean through everything hooked to the main panel. Let alone your lighting could very well be 277 volt three phase, in which case all he did was unhook 1 phase and worked on a system with 2 live lines still operating.

Saw this done at an apartment complex where 1, 2 ton A/C unit was being replaced, noone touched a breaker, blew every electronic device connected to 24 apartments and many light fixtures etc. Cost the Landlord and the Contractor more than a million dollars before it was said and done.

Find a local Commercial Journeyman electrician and ask him to go to the pow-wow with you. I'm quite sure the pin head responsible will all of a sudden "No Habla Englais".

Ray