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Discussion Starter · #1 ·
I'll be starting a job as a facilities maintenance leader next week and one of the dilemnas the facility is experiencing is recurring lightning damage to the security & fire system control boards. The buildings are less than 4 years old and I can see that the brick buildings have lightning protection throughout. Not sure if the buildings (8 of them) have concentric grounds under the foundations or just rods driven into the ground.

The company that installed the fire & security systems, and maintains them, can't figure out what the reason is with all the protection existing.

According to the director, the system boards fry even when lightning hits close by--not a direct hit to the building.

Just doing some brainstorming now so I can target some things to look at. But if everything checks out, isn't there some sort of capacitor that can be wired in line with the power feeds, neutral, and ground wires?

Anyone experience similar problems? If so, how did you correct your situation?
 

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Proper bonding!

Make sure that these systems are properly bonded to the building grounding electrode system, NOT grounded separately.
 

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This is a perplexing problem, especially since there are places that seem to be targets for lightning. I know of no science that explains it.

One thing to consider is that lightning is the discharge of a charge that builds up between earth and sky. If that charge can be "drained" off through lightning rods, then the sudden discharge (arcing) can be reduced or prevented. Odds are that the security system is serving as a good path to earth ground and might be fried without any actual lightning.

You could try building an alternate path that doesn't include the panels. I swear, some of the grounding techniques on metal buildings actually increase their conductivity to earth ground and make them perfect targets.
 

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Discussion Starter · #5 ·
During the walk-through guide with my boss, I asked him if the systems were tied in to the building's ground, but he didn't know. The roof is properly lined with lightning rods, though I did note that from the roof to the block & brick walls, the down conductors are thick braided aluminum. I thought the lightning ground conductors had to be copper. :blink:
 

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How many buildings & are they fed via different services?

Is the fire/ security system cable ( low voltage- ie ethernet, UTP, etc) routed between buildings?
 

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Discussion Starter · #7 ·
^^ I'll find that out next week when I start the job. I'll scrutinize the prints to see if the grounding system was properly designed. Of course, the installation may differ from the design....I've seen way too many cases of that with no "As-Built" updates made.
 

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Proper grounding above NEC mandated
Multilevel TVSS, high quality, properly installed.
 

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Is the facility fenced with security chain link fencing (10' or higher) if so check to see if the fence is bonded to the electrical service, ground and metal water supply. If so you will find more problems with the electrical service and copper plumbin pipes.
 

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Should have added does this facility have LPS (Lighting Protection System)
What is the routing of the FA and telcom conductors?
Are there optical couplers in use between the buildings.
Proper grounding above NEC mandated
Multilevel TVSS, high quality, properly installed.
GROUNDING to include low resistance to earth and bonding (as noted by others)

There are most likely a variety of issues that are causing yur problems. You should consider hiring a SPECIALISTS in LPS protection. These are more than just your local LPS company you need someone with a broad insight into the issues and how to resolve the short comings at this location.
 

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IF the fence is grounded to your building services cut the grounds and install seperate grounding/earthing/bonding for the fence. Ensure you have proper building grounding. When you get there ask if there have been problems with copper water supply pipes deteriorating from the inside out. If there were lighting ups systems original to the builds I bet they have been abandoned and replaced with generators.
 

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Discussion Starter · #13 ·
^^ The complex is 4-5 years old at the most, so I doubt any deterioration has occurred yet to pipes, nor have they altered any system. You all have provided me several good things to look at though! :thumbsup:

I'll keep ya posted!
 

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so I doubt any deterioration
Number 1 trouble shooting mistake you are assuming something you really do not know. Lightning hits will deteriorate the earth connection of your electrodes, water, humidity will corrode connections....NEVER ASSUME.
 

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IF the fence is grounded to your building services cut the grounds and install seperate grounding/earthing/bonding for the fence
And why would you say this. you have substantiation for this statement?

quote]If so you will find more problems with the electrical service and copper plumbin pipes. [/quote]

Please explain?

NFPA 780 Standards for Installation of Lighting Protection Systems I believe recommends bonding of all metqallic components. I'll be in the office on Tuesday and post.
 

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Discussion Starter · #17 ·
Update: I talked with the contractor that services the fire system and security systems. Found out that they actually have more problems burning up PC cards on the fire system. This is a design where all 8 buildings are "looped" together & feeding an annunciator in the 24-hr security desk for monitoring. They showed me 2 "cards" that were burnt where the signal cables were connected.

The cables are regular red fire cables with the foil shielding and is buried in PVC from bldg to bldg. Nothing else is in the PVC but these signal cables. The technician's best guess is that the cables are picking up a surge via inductance when lightning strikes nearby. The complex does sit on the highest ground in the county and gets a LOT of lightning strikes.

According to the tech's, the fire & security systems' power supplies don't really get damaged, which is leading me to believe that the facility grounds are working. However, one bldg DID get a direct strike and the fire system main PC board fried.

Does inductance sound like a possible cause? I've asked them to submit a proposal to replace the cable with fiber optics.
 

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Inductance? - maybe. Is there physical seperation between communication & power conductors sharing the same ditch? Secondary or primary?

Does the alarm cable routed between the buildings have a metallic shield? If so, is this bonded to the cable entry ground bar at the point of entry at each building?

Other possible causes-

A difference in ground resistance between the buildings.

A recurring fault condition causing a neutral or ground displacement.

Bottom line is communication modules in many security / fire panels won't tolerate even minute surges or transients.

You're on the right track... optically isolate the panels. Remember that if you replace the cable between the buildings with fiber you will need to bond the metallic central strength member and armor at the building point of entry unless you use an all dielectric fiber cable.
 

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ligthing damage

i know someone will not agree with me but this is just my input , most electricians think that a tvss or a arrestor is a capacitor , generally i must disagree , its a mov metal oxide varistor this is like a semiconductor two plates and the metal oxide in the middle of these and other stuff like ceramic and bla bla . when the rated voltage of that mov is hit by a lighting strike or a overvoltage problem it conducts and gets hot shorting out that voltage between the plates by conducting at only that rated voltage of that mov . shorts the fault , next this is just my thinking on multiple buildings on a common ground grid or site if a lighting strikes in that area or near that area ,it gos to ground we think but does it? , if you have multiple paths of high voltage they are split up and take many different directions its high magnetic effect when it hits induces current everywhere on site , you are not going to stop it!! i feel tvss,s and lighting arrestors are a waste of time on a service. it needs to be stop before that point! but i think lighting protection is or must be installed on equipment directly on that equipment only to protect it . let a strike hit give it time to travel in the grounded circuit and protect each system alone .the smaller hits scatter will be less in each area . its going there anyway .a little fire is better than one big one .i think most jobs have lighting arrestors per spec to be installed on fire alarm systems on there circuits in there fa tc cabinets meaning the power branch and the signal circuits , independent from the main service stuff , has anyone ever heard of the running ball theory if ground point is above all other ground points that one will be hit normally. the test is by rolling a computer generated simulated ball off high point of roof and as it rolls off the edge and hits the earth thats your protected area at that point from the point of start, meaning you might install one main rod or tower rod in the center of this area and ground it meaning above all other rods ,in florida we have this everday in the summer it rains at 4 pm every day somewhere and we get lighting strikes, even on sunny days no rain , just clouds overhead strange stuff,
 

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Discussion Starter · #20 ·
Inductance? - maybe. Is there physical seperation between communication & power conductors sharing the same ditch? Secondary or primary?
-- Yes, it is only the signal wires, which is really a typical fire alarm (red) cable with foil shielding. There is no AC power in the same conduit. I took a close look at the PC card and where it burned up, and it is just after the signal wire terminals on the card...the solder track burnt up. The "AC power side" of the board(s) seem to be taking the lightning hits pretty well.

Does the alarm cable routed between the buildings have a metallic shield? If so, is this bonded to the cable entry ground bar at the point of entry at each building?
-- According to the service contractor the foil shielding is NOT grounded to the building ground. When I heard this, I suggested that they run a solid copper wire jumper to bond the foil shielding to the panel ground.
 
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