Lightning Protection Conductor Sizing

[ROMM]

Hi All,

Anybody know of how to size lightning downconductors from lightning masted air terminals.

Regards

 

[alehman]

NFPA 780 specifies conductor sizes. Two classes of systems are specified, depnding on structure height. There are several sizes of conductors specified in each class. 'main conductors' for class 1 are roughly #2 AWG and for class 2 are roughly #2/0 AWG. In the U.S., lightning protection systems are constructed with special braided conductors which are not exact AWG sizes.

 

[ROMM]

Thanks Aleham, Can you help me i am in australia, where
can I see nfpa780 and im not sure of the #2/0 awg? what does this mean. I am used to 37/2.03(120 sq mm) conductor size notation. Your assistance is greatly appreciated.

 

[alehman]

NFPA 780 is published by the U.S. National Fire Protection Association. It is a lengthy document on lightning protection design and is available for a fee from

http://www.nfpa.org/catalog/product.asp?pid=78004&src=nfpa

AWG (American Wire Gauge) is the English/US wire size designation. See

http://www.aseapower.com/technotes/tn_004.htm

NFPA specifies the stranding no/size as well, which you may not be able to match in Australia.

 

[cuky2000]

Down conductor, for lightning protection are sized according with structure high per NFPA.
For additional references, consult the NFPA - 780, NFPA- 78 and Tables 4-4.3 A & B in the proposed NFPA 781 document enclosed.

http://www.lightningpreventor.com/pdf/nfpa/nfpa.pdf