Ground Brass Sculpture on Roof?

[TheGingerElectrician]

I have a customer who called to ask if we could ground a metal sculpture on his roof here in TN. The code book doesn't really address this does it? It's a standard composite roof and stick frame on a detached building. I don't know if the building has its own ground rod but we would certainly add them in the event he doesn't have them and bond to the panel out there. Any advice if we need to bond the brass sculpture or if even necessary and where I can go to size it? 250 only covers electrodes for alternating current systems...

 

[infinity]

Why does he want this grounded? Is this for lightning protection?

 

[TheGingerElectrician]

Why does he want this grounded? Is this for lightning protection?

Yes he is concerned about lightning protection but we would also need to bond it if we did something like that correct?

 

[gary deinhard]

I have a customer who called to ask if we could ground a metal sculpture on his roof here in TN. The code book doesn't really address this does it? It's a standard composite roof and stick frame on a detached building. I don't know if the building has its own ground rod but we would certainly add them in the event he doesn't have them and bond to the panel out there. Any advice if we need to bond the brass sculpture or if even necessary and where I can go to size it? 250 only covers electrodes for alternating current systems...

A number 4 copper or # 2 copper is sufficient. Down to a ground rod. Not to the service.

 

[herding_cats]

I had a physics teacher in college that was a renowned expert on lightning. He wrote a book about it about 20 years ago.

He claimed that lightning rods did NOTHING to redirect energy or to protect anything. He claimed that lightning rods do not attract or redirect lightning strikes at all. He was a member of that go to area I think in west Texas or new Mexico? that has the highest rates of lightning strikes. He was a really weird guy. I wonder if he had been hit too many times?

 

[tom baker]

A number 4 copper or # 2 copper is sufficient. Down to a ground rod. Not to the service.

First, a lightning protection system ground wire goes to a separate electrode, which is bonded to the building GES.
Second, lightning protection systems have very specific requirements, our advice is to advise the owner that the design and installation must be done by s UL certified company. Will a ground wire work? Maybe. But if not and you installed you would be liable.

 

[tom baker]

I had a physics teacher in college that was a renowned expert on lightning. He wrote a book about it about 20 years ago.

He claimed that lightning rods did NOTHING to redirect energy or to protect anything. He claimed that lightning rods do not attract or redirect lightning strikes at all. He was a member of that go to area I think in west Texas or new Mexico? that has the highest rates of lightning strikes. He was a really weird guy. I wonder if he had been hit too many times?

Cell towers have extensive lightning systems that can take direct strikes with no damage

 

[infinity]

Yes he is concerned about lightning protection but we would also need to bond it if we did something like that correct?

As Tom stated if the concern is about lightning then a lightning protection system should be used and not just a random ground rod and a piece of wire. Lightning protection system use braided style wire, air terminals, and electrodes. They also get connected to the building GES.

 

[herding_cats]

Cell towers have extensive lightning systems that can take direct strikes with no damage

Yeah that makes sense. I’m just repeating what he always talked about.

 

[Rock86]

I had a physics teacher in college that was a renowned expert on lightning. He wrote a book about it about 20 years ago.

He claimed that lightning rods did NOTHING to redirect energy or to protect anything. He claimed that lightning rods do not attract or redirect lightning strikes at all. He was a member of that go to area I think in west Texas or new Mexico? that has the highest rates of lightning strikes. He was a really weird guy. I wonder if he had been hit too many times?

Did he own a DeLorean?

 

[herding_cats]

I don’t think so.

 

[Tulsa Electrician]

I had a physics teacher in college that was a renowned expert on lightning. He wrote a book about it about 20 years ago.

From a scene in the movie, hunt for red October. What book? One of favorite parts.

If you can find the title please post. I would like to read it.
Thank you.

 

[herding_cats]

 

[Tulsa Electrician]

Thank you.
I will give it a read.

 

[TheGingerElectrician]

As Tom stated if the concern is about lightning then a lightning protection system should be used and not just a random ground rod and a piece of wire. Lightning protection system use braided style wire, air terminals, and electrodes. They also get connected to the building GES.

So they do need bonded to the GES like i was thinking then...

 

[xformer]

A number 4 copper or # 2 copper is sufficient. Down to a ground rod. Not to the service.

IMHO... I would use lightning protection cable.

 

[Rock86]

If you have access, thumb through NFPA 780 for lightning protection.

 

[synchro]

As Rob (Infinity) mentioned above, lightning protection systems often use braided cable, and it may be flat and relatively wide. Also copper strap is used when it's practical to do so. This minimizes the loss of the conductor's effective cross section due to the skin effect at higher frequencies. Lightning has significant energy at 10 KHz and beyond. Some info about this is at the link below:

https://www.eetimes.com/get-grounde...evices-from-lightning-transients-part-2-of-2/