Lightning protection for metal pole building

[srs]

I got into a discussion with some friends concerning lightning protection for metal pole barns. As expected a few opinions were given whether one should have some type of lightning rod, grounding, etc. Here are some conclusions as to what was recommended. By the way the building is a Morton metal pole building with a standard cupola on top with a Morton weathervane. The building will eventually have water supplied to it and a 100 amp subpanel box run from the home.
Some people said:
(A) don't add any protection,
(B) one person said add lightning rods,
(C) and one person said to ground each corner of the metal building with copper wire and an 8' grounding rod.

(A) The reason for not adding any protection is the odds are the building will not get struck by lightning
(B) The reason for adding protection with lightning rods is if struck it will send (hopefully) all electric directly into the ground, but with lightning rods (I thought) it would attract lightning.
(C) The reason for grounding each corner of the building is that if struck the electrical discharge will dissipate safely (breakup, lose energy) and send the current into the ground. I kinda like this thought, but I have no idea if this is true or not.

Anybody have some good thoughts here? Inspector 507???

 

[hilld]

My metal barn is grounded directly via 2 ground rods. I had to install the ground rods as I have seperate electrical service to the building. In addition, the building is also bonded to the electrical ground (all metal building). I don't know if this is sufficient for lightning protection, however, I am assuming ( I could be wrong ) that since I am grounded, adding more grounding rods would not add to the level of protection of the building.

Derek

 

[HappyCPE]

Thunder and lightning as I type!
Here is a website that might help:
http://www.lightningarrestors.com/installation.html
Or, try this one:
http://www.lightningrod.com/manual2_example.html

My understanding is that, rather than attracting lightning, a system will tend to dissapate the natural charges between the ground and clouds, making the chances of a strike that much less. No, I'm NOT an expert!

 

[srs]

thank you for the info.

 

[Paddy]

Do you have a concrete slab? Is there wire or rebar in it? If yes, you have nearly a perfect Gausing/Faraday cage if you do a little bonding slab to sides. That is completly surounded by a conductive material. Inside the skin V=0

I'm a high voltage test engineer and perfom tests called Lighting impulse tests at 1800 kV, 1,800,000 volts. The labs have demonstration days where cars are flashed to and Cages with people inside. Note in the photo, there is a person inside!

 

[Lucky1]

Recently bought a copper and brass weather vane at a auction I was at. My guestion is does this have to be grounded? It is going on a metal pole shed. thank you

 

[MrJimi]

I am by far NOT a lightning expert! I have lived in Florida for 26 years and our stuff has been hit by lightening and 5 out of 6 times, it come in the darn ground. Last time it hit a 4 foot tall chain link fence that had a electric fence charger wired to it but NOT plugged in?
Imagine lighting coming in the ground and wiping everything plugged in. 200 amp panel and all the breakers etc. Then our sorry insurance company drops us and wont pay for all the damage. Thats sad
thanks
Jim

 

[SPIKER]

lightning is fun stuff for sure.

most codes, NEC ect will require that metal buildings be bonded and grounded by grounding rods/methods which are OK too many issues but yes there needs to be some sort of approved grounding methods, the metal skin needs this and the elechookup will need bonded as well when done...

as far as lighting rods, normally the rods are all tied into a metal wire which is then run all the way down into the ground with a grounding rod. the cable/wire will draw the lighting around the structure into the earth, hopefully avoiding damage to the building. usually only works ONCE then requires repair. (new wire or rods or at least a good straighteneing...

anyhow be sure that the metal siding is fully in good bond to each piece/section and side to side and roof to sides. this will not only help prevent damage from strikes but from errant electrical issues which can cause rust of corrosion to develope...

mark M

 

[srs]

Paddy, are you saying to bond the metal walls with the rebar/wire and then attach that to a ground rod? If so, do I do it at one point or several? FYI, the concrete will be installed a few months after the building is completed. Thank you for your help.

 

[Paddy]

Yes, Bond your walls to the floor steel. As you saw in the photo, once you creat the cage effect, all is safe in side. As far as grounding, the principle is to protect with in. A car is not grounded but the contents (people) are safe in a strike. Grounding won't hurt but in the case of a direct strike to a metal building, you couldn't keep it from going to ground if you tried!