Size of down conductor

[Abdu]

Hi all,
Please, I need to know what is the size of down conductor should be chosen for connecting the lighting aerial mounted above the telecom tower to the goround?.
What British or American standard recommends,?
Thank you so much in advance for your assistance.

 

[tom baker]

There is a separate NFPA standard - 790 - for lightning, its not in the NEC. Size of the down conductor is a basic part of lightning protection, you need to get a qualified person for your lightning protection system.

 

[tom baker]

Telecom towers if metal, typically won't have lightning protection as the tower itself is a lightning rod, and is very low impedance.
What's important is the grounding of the tower, get a copy of motorola R56.