Grounding a Tin Roof

[BXMMCC]

Well, seems like the house hasn't been bothered by lightning for a few years, nor the roof, so why not gamble that nothing will happen for a few more?

[DaveNay]

</font><font color="blue" class="small">( Well, seems like the house hasn't been bothered by lightning for a few years, nor the roof, so why not gamble that nothing will happen for a few more?
)</font>

Because [insert diety of choice here] reads TBN, and has now realized that he/she/it has missed that house for the last 200 years, and there is a lot of catching up to do! [img]/forums/images/graemlins/frown.gif[/img] [img]/forums/images/graemlins/frown.gif[/img] [img]/forums/images/graemlins/frown.gif[/img]

Dave

[chim]

Our company has done projects where the lightning protection systems were a part of our contract. We used a specialty subcontractor for the installation of all the lightning protection systems, without exception.

It looks easy enough to install, so long as you would have the correct design. One big concern is the potential to attract lightning - then not have the proper grounding path to deal with it. Having the wrong installation would likely be worse than having none at all.

And yes, they do use stranded aluminum for roof circuits and downleads. It has a weave to it (not a twist, like normal wire). Lightning rods are very sharp on the tip (to start the arc). There's a nuclear-powered lightning rod (covers an extremely large area and one will replace gobs of regular rods). Believe it or not - the first lightning protection subcontractor we used had a foreman named "Rod".................chim

[fivestring]

Does your company or subcontractor grant a warranty?
Guarantee that lightning will not strike the protected item?
Guarantee that if lightning does strike the protected item that it (and all contents and attachments) will be replaced by your company or subs?

Lightning and moving water (streams, rivers, freezing water) are the two biggest forces we know of.
Hard to stop either one.
Just ask folks that get flooded out by OLD MUDDY.

[chim]

On the projects I've been involved with, there were no warranties covering subsequent lightning damage. We have used two different reputable firms as subcontractors. At the completion of their work, the work was inspected and a "Master Label" was provided certifying the work was done properly.

I wasn't joking about nuclear-powered lightning rods. I think they went by the name "ellipsoid". They contain a small amount of radioactive material that is supposed to enhance the ionization of the air and have the cloud discharge before it has a chance to build into a damaging strike.

People from both subcontractors and at least one electrical engineer told me that although we have effective lightning protection systems, there was still a lot that is not fully understood about lightning.

[reb]

About 30 years ago a neighbor's house was hit by lightning and burned to the ground. As an electrical engineer and a confirmed diy-er, I figured I could install some kind of lightning protection system on my house. After a bit of research I concluded there was probably not enough scientific knowledge for a fool-proof system and whatever I did might be viewed by an insurance company as contributing to the problem if my house were hit. Therefore, I just cross my fingers during a storm. This is an area where I would go to a pro if I wanted to try something.

[cisco]

My contractor is about 80% through building a garage / apartment on my country property (30 X 42 ft, 2 story, 35 feet high, with 2 nine foot high doors for my tractor and boat bays). Such will have a coated aluminum roof, and the lightening protection stuff seems reasonable (done by a lightening protection subcontractor). There are rods along the apex of the roof every 6 feet or so, connected to each other in the attic with what appears to be 3/4" thick and loosely braided copper wiring. The wiring connects to grounds (8 foot in ground stakes) on each end of the dwelling, with the copper wire inside conduits going down those 2 sides of the dwelling. What else - hmm - surge arrestors on the main electrical line in and on the phone line. Despite all of the above, I will have lightening damage insurance, along with usual flood, etc. - I, like prior posts, may think the system, installed by professionals, will work, but I'm not certain, and I've seen what a lightening strike can do to a house.

[Logan]

Lightning seems to have a mind of its own and does what it wants when it hits. I had it hit a pine tree that was about ten feet from a shallow well that is about twenty feet from the house. It followed a tree root to the well and came into the house through the wiring, didn't hurt the well nor another, my deep well, on the same line. It came into the panel box in a closet four feet from where I was sitting at this computer. It knocked out a 13" TV in my daughter's room, got the microwave in the kitchen, and killed one of the two garage door openers and caused an ugly stain in my computer chair. It didn't make a mark on the well house or my home.

[SPIKER]

yep it will cause many a ugly stain on the carpet floor chair or any place a person may be standing at the time!.

We had one heck of a lightning storm last night and today too.!

last year this time my sisters house was nearly burnt down cause of it . when it hit it burnt the house 2 up from here (its replaced now with new construction) and burnt out her wiring panel and phones. she was lucky to be home and got the fire dept there soon enough to stop hers form going up!. though she also needed to call the carpet cleaners too! lol

her hubby hosed it down with a dry chemical extingusher and put it out before the got ther, but flames were already comming out the ves of the neibors house... the hosue between them not a scratch! (sity lots of aobut 80 feet or so wide.)

Mark M [img]/forums/images/graemlins/confused.gif[/img]

[To20Chris]

The individual pans in a standing seam roof are not all that well connected to each other electrically, especially after 70yrs! You would have to bond a ground conductor to each pan in order to make it effective. It has to be a really low resistance path (hence the low-inductance weave in the conductors) or it is not much good. Also, the roof is probably tern (tin coated steel), so you would have a hard time bonding anything to it that would not corrode after a few years (dissimilar metals). Go out and fine some really cool old lightning rods (the kinds with the glass spheres in them), and have someone put them up right. Or forget about it - you've got a much better chance of getting hurt on the way to work!