Lightning strikes the third time. Thoughts please.

[rick hart]

There is a church, built late 1990 that has been struck at least three times causing damage to equipment but, not any to the building or 1600A fusable, six switch service entrance. The building is wood frame, on slab in the highesty point in the county. The EGC (at least a 2/0 cable is visible as it goes into the attic. I have not taken the panels off to see if this is the only EGC of if one also is in the slab.
A Franklin type lightning arrestor system is installed but it does not appear to be bonded to the Equipment Grounding Electrode. Their cable is bonded to a #6 copper ground for the phone utility. I did not see any bond between the phone an electric service.
This building has a good quality 4 wire fused TVSS on the service entrance. The fuses never blow on the TVSS, the fuses in the switch board don't blow BUT fuses down stream from the service for A/C controls, smoke beam detectors and electronics are hit hard.
I noticed that the computer network patchbay, DSL modem and Fire control ( about 100 feet away from the service entrance) also have a #8 solid copper ground wire attached to the cabinet but I do not see where this was grounded. Almost all damage is quite a distance from the electrical service but nothing burned or missing.

Questions:

1. The lightning system and the service entrance need to be bonded together?
2. The phone, data hub, fire alarm ground need to go to the service entrance rather than "pick up a ground somewhere" that we see all too often
3. With fuses blowing away from the service entrance, does that indicate that the surge current is coming from somewhere else. I'm thinking current swell rather that a voltage transient is causing these problems.
4. Has anyone had a similar problem that was fixed by-------?
Thanks in advance for any thoughts. I need to find the source of this damage.

 

[physis]

Re: Lightning strikes the third time. Thoughts please.

I really know almost nothing about lightning compared to some of the other guys but I have a questuion though.

Are lightning rods used anymore nowdays? Wouldn't this be like exactly the kind of place you'd use one?

I'd think the buildings gonna be hit many more times in the future. I'd be really interested in putting it somewhere away from the building if I could.

 

[bphgravity]

Re: Lightning strikes the third time. Thoughts please.

Perhaps the church needs to change religious affiliation?

The lightning protection system must certainly be bonded to the grounding electrode system for the service. You may also need to add more air terminals and down conductors. See the NFPA 780 for lightning protection installation and design.

 

[physis]

Re: Lightning strikes the third time. Thoughts please.

Perhaps the church needs to change religious affiliation?

 

[physis]

Re: Lightning strikes the third time. Thoughts please.

Are air terminals little lightning rods?

 

[charlie]

Re: Lightning strikes the third time. Thoughts please.

Are air terminals little lightning rods?

Air terminal is the correct name for lightning rod?

 

[physis]

Re: Lightning strikes the third time. Thoughts please.

That's nifty. All of a sudden lightning rod is slang? Must have been superceded by NEC terminology.

Edit: Error B

Edit: Air terminal does sound cooler though.

[ July 15, 2005, 04:48 PM: Message edited by: physis ]

 

[rick hart]

Re: Lightning strikes the third time. Thoughts please.

I have some more info that I hope will stir some comments.
The service GEC (2/0) runs through the attic in close proximity of data cables, telephone trunk line, fire system cables. Cable length is over 150 feet before clamping to the cold water supply. Most of the water supply was ran in the attic also, leaving just about 30 feet under slab before attaching to the city supply- PVC.
There is a driven rod at the service with a #6 THHN going to the ground bus in the bottom of the switchgear. The 2/0 attaches to the neutral terminals above; bonding jumper is installed. I suspect that the TVSS is shorting to ground the strike but, since there is not a solid path to ground, the current is finding its way to ground through all sorts of equipment.

I don't think there is an effective ground here. I'm thinking that a 30-40 feet long, 2 foot deep trench should be dug with driven rods every 10-15 feet and cadweld a 3/0 copper cable should be added. I figure that will be a more attractive path for a strike to follow than the cable in the attic.
As far as the affiliation- maybe they are on to something there and it's the devil that's scared! ;-)

Once again, thanks for any comments.

 

[benaround]

Re: Lightning strikes the third time. Thoughts please.

rick,

In the grounding vs. bonding Forum, Under the topic of satellite dish mast,Bennie,has some words of wisdom on lightning. Check it out.

frank

 

[redfish]

Re: Lightning strikes the third time. Thoughts please.

If aluminum air terminals are used, then a braided aluminum cable should be used as the down conductor. You should also run a 2' deep trench all the way around the building if possible. Drive a 3/4" ground rod every 30 -50 feet and cadweld 2/0 across them to form a ground ring. Bond the down conductor(a down conductor should be run down each end of the building and if possible down all four corners)to the grid, and bond the comm. hub to the grid using 2/0 and cadweld. Lightning protection is a big job and not inexpensive, but it will pay for itself by preventing damaging lightning effects.

 

[mc5w]

Re: Lightning strikes the third time. Thoughts please.

An assisted care facility went up about 3 blocks from where I live a few years ago and it has a lightning rod system.

Army Manual 5-690 requires that the ground ring for a lightning rod system be at the bottom of a 10 foot deep trench and the ground rods driven below the trench if soild conditions permit. The ground ring is required to be at least 1/0 copper. You can download Army Manual 5-690 for free and distribution is unlimited - not classified or copyrighted.

Army Manual 5-690 also has a lot of other details of how to build a lightnig rod system as well as other details of any other heavy duty grounding situation.

[ July 19, 2005, 01:48 AM: Message edited by: mc5w ]

 

[rick hart]

Re: Lightning strikes the third time. Thoughts please.

I never knew that existed- looks a little like NFPA 780 in parts. Thanks for the tip. This looks exactly like what I need to know.