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#201890 - 06/30/11 12:32 AM storm damage  
schenimann  Offline
Joined: Feb 2008
Posts: 193
Western North Carolina
We have had a rash of thunderstorms here recently. It seems like almost everyday we have the daily afternoon lightening show. The sky goes dark and the power flickers.

Saturday before Father's Day our church had a wedding during one of these. Well it turned out the storm caused a lot of damage. They lost the dimmer packs for the lights, tv lights, the sound system(amps, controllers, speakers, sound boards, etc) and the video system(HD cameras, 2 projectors for the 8 ft screens, etc.) Our church is on the cable network and streams every service with HD cameras so there is a pretty extensive audio/video department. So far the estimate is up to about $250k for the video alone.

They are meeting with the insurance people next week to determine coverage.

They are looking at updating the surge suppression. The utility has a system that you can rent for around 30/mo. This seems good except that because it is commercial it is not waranteed. From what I understand, part of the issue wasn't so much the lightening but the power flickering causing the equipment to cycle on and off. You may be able to shed light on this for me. I am pretty good friends with all parties at the church involved and would like a better understanding of what is happening.

Is there a device that you can install on circuits to cause the whole circuit to drop out if the power flickers? It would require a manual reset but would stop the power cycling.

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#201891 - 06/30/11 01:36 AM Re: storm damage [Re: schenimann]  
LarryC  Offline
Joined: Jul 2004
Posts: 783
Winchester, NH, US
I suspect a significant difference in voltage was created between the structure's electrical system "ground" and the cable system "ground" due to local lightning strikes. The excess voltage followed all possible paths to earth and unfortunatly some of it was thru the A/V equipment.

How old is the church's electrical Service? Specifically the grounding system.

What is the soil like? Red clay?

As far as fluctuating voltage levels, a good quality UPS should minimize the dropping out of the electronics due to low voltage.

A multi-level approach to prevent this issue from happening again can be as follows:

1) Keep all electrical and electronics referenced to the same level. It is not the voltage that did you in, it was the DIFFERENCE of voltage that did you in. Create a quality low impeadance earthing system. TIE EVERTHING TO IT! That means the electrical service, phone service, cable service, structual steel, in ground pool and other water features, and all other metal piped services. Create a good ground reference in each room with an electronics rack. Try 6 inch wide heavy duty copper flashing as a ground conductor. Make all of the bonding conductors as short as possible and as wide as possible.

2) Multiple levels of surge suppresion. Use a surge suppression system at the main panel. Followed by one at the sub panels that feed the A/V systems. Followed by local surge suppressors at individual loads if necessary. Install surge suppression systems on the Phone lines where they enter the building. Do the same for the cable lines WHERE THEY ENTER THE BUILDING. All of the surge suppressors should be bonded to the same grounding system.

3) Protect against brownouts and short term power outages by using QUALITY Uninteruptable Power Supplies (UPS). Quality means units that isolate the output power from the input power.

I am assuming that the church was built or updated with properly grounded outlets everywhere and all of the wiring is in steel conduit.

Does the church have a lightning protection system? If so, is it connected the rest of the grounding system?

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