[TowerTalk] Grounding Standards

[Michael Keane K1MK]

At 03:04 PM 7/27/2007, Jim Lux wrote:
>At 08:32 AM 7/27/2007, Jim Brown wrote:
> >On Fri, 27 Jul 2007 11:04:26 -0400, Alan NV8A wrote:
> >
> >The grounding requirements of NEC are not terribly demanding, so
> >the stuff I'm seeing quoted here re: tower grounding seems a bit
> >suspect. I'd like to see citations of the numbered paragraphs that
> >call for the large conductors being discussed before I take it as
> >gospel.
>
>
>I think there's some conflation of the NEC grounding requirements
>(easy to meet for most cases) and NFPA lightning ground requirements
>(NFPA 780) and various manufacturer (e.g. Polyphaser) recommendations.
>
>(FWIW, NFPA 780 in the year 2000 revision started to recommend the
>use of radial ground conductors below ground level ot distribute
>lightning charge)
>
>There's also an IEC standard IEC62305 for lightning protection.

Some of the  changes in grounding standards that have been mentioned 
(10 ft. ground rods vs. 8 ft,; 2/0 AWG copper ground leads vs. 6 
tinned copper, etc.) are from the latest revision of the tower spec 
(ANSI/TIA-222 Rev G).

Since ANSI/TIA-222 Rev G is now included by reference in the IBC 
which already has been (or shortly will be) adopted as the state 
building code in most states, compliance with those standards are 
mandatory in most locales.

As the IBC also includes by reference portions of the NEC and the 
NFPA as well as ANSI/TIA-222 Rev G (specifically in regards to towers 
) there is (potentially) less confusion about what the building 
inspector will want to see before issuing a permit.

73,
Mike K1MK

Michael Keane K1MK
k1mk at alum.mit.edu