Proper grounding of lightning protection

[trek1]

I have been searching the NEC and would like any input into grounding radio electronics (base stations and antenna systems). With new installs it is easy to spec a bus bar to tie to. In an older building, without a ground window/bus bar is it permissible to use existing electrical conduit? There is also a fire protection sprinkler stand pipe. Any help would be appreciated. If you know the specific section that would also be helpful.
Thanks

 

[dereckbc]

Re: Proper grounding of lightning protection

Trek1, there are some sections in the NEC that give minimum safety requirements (not operational). Do not have my code book in front of me but I think it is articles 800 through 840. One is for antennas, CATV, telephone, etc. They are all basically the same giving minimum wire sizes, length etc.

You would not want to run any discharge grounds inside the facility to conduit or a ground window bar. They go directly to the GEC, or electrode system like a ground ring.

If this is a commercial application like broadcast, common carrier, or wireless, these industries have there own proprietary methods which are compliant with NEC, but not covered by the NEC.

If this is for buisness use on a shoe string budget check out the ARRL.

[ December 18, 2003, 02:31 PM: Message edited by: dereckbc ]

 

[tom baker]

Re: Proper grounding of lightning protection

Radio mast grounding is covered in Art 810, if you use coax its covered in Art 820. Typical commerical practices is to use a single point ground, with a copper buss bar just inside the building, for the impulse supressor. A bonding jumper extends outside to the electrical grounding system and antenna mast.
A very good reference is Polyphasers " the grounds for lightning and EMF protection" Also the polyphase web site has a lot of good white papers. Keep in mind even though the polyphaser info is good, you'll need the NEC to comply with the grounding and bonding requirements.