Lightning or Static rod on the top of a house

[daronwilson]

Hey folks,

We're not big lightning attractors here on the left coast, but I know many of you folks deal with a fair amount of it. I have a customer with a metal roof and they are concerned with lightning. The roof is likely ungrounded, but they want a 'lightning rod' installed at the peak. I really can't find much in the NEC for sizing, and frankly don't know how big and what to go with.

If anyone has any direction they can point me to with a link for guidelines, I'd appreciate it.

thanks,

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[skip555]

I was just reading about this

the book is "creative homeowner wiring and advanced projects"

dont let the name throw you its actually a good primer

isbn 1-58011-062-2 I checked my copy out of the local library

they have a chapter on lightning rods and they quote the following as refrence

nfpa -natinal fire protection association "NFPA 780 Standards for installation of lightning protection systems" 1997

LPI -lightning protection Institue : Standards and practices LPI-175

UL -underwriters lab standard ul 96A

 

[ANFPS26]

Here is one link I found on a Google search:

http://www.lightningrod.com/manual2_example.html

Jim

 

[mikeydidit]

Here is another for you Daron.

http://www.bobvila.com/wwwboard/messages/72786.html

Mike Jones
LSUHSC

 

[daronwilson]

Thanks, found the NFPA reference shortly after posting, the others look interesting too. Looks like more work than the average customer is going to be willing to pay, but good info none the less.

thanks guys!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[RandyVSP]

Daron :

Another option is to use a copper ground rod, inverted, and mounted in a bracket, then use 1/0 insulated copper to the ground, and then exothermic weld this to at least 2 - 10 ft ground rods.

I used something like this on a FM Broadcast tower years ago and it worked. Actually saw direct hits on it!

The reality is unless they are on top of a hill, I dont think lightning is a issue. My area has hundreds of metal roofs and none seem to be a issue. BUT, If they have locust trees around, better double the grounds....they get hit alot more than any other type tree....

Randy

 

[dforney]

Safe to just skip it. Up north it is more common to see them for some reason, somebody is making some good money on them.. but you just do not see them around here, and this is the lightening capital of the world. They aften do not appear on 1 or 2 story commercial buildings either. There is no code requirement and we nor our associated firms just don't specify them.

Just have them plant a tall tree 20 - 30 yards away. (-:

 

[skip555]

dforney

which lightning capital of the world are you in ?

Im in sw fla which I had always heard to be lightning capital but I have seen other regions make the claim.


around here there are lots of metal roofs without lightning rods

I do however see them on some large buildings

 

[dforney]

Bradenton / Sarasota / Tampa Area.

Yeah, Under the stories we don't spec them, 3/4 stories optional, over that - mandatory. Exception being theme park buildings in special scenarios.

 

[skip555]

Bradenton / Sarasota / Tampa Area

me to

 

[dforney]

So it is safe to say we know our lightning then.

 

[dforney]

Barely relevant to the topic, however, I stumbled across this website today.. a little interesting - for this area anyway.

http://www.scgov.net/lightning.aspx

 

[skip555]

thanks

I bookmarked it in my weather folder

another cool way to waste time here in the coming months