[TowerTalk] Grounding Standard

[Jim Lux]

At 07:46 AM 7/26/2007, Larry Burke wrote:

>As I understand it, back on January 1, 2006, tower grounding standards in
>the US were specified in ANSI/TIA-222-G-2005 to state that the connections
>between the tower and grounding electrodes, or between the electrodes
>themselves, shall be no smaller in surface area than 2/0 solid (way up from
>#6 AWG in the previous revision of the standard). Also, the grounding
>electrodes shall be a minimum of 5/8 inch diameter and 10 ft long.


The key here is "surface area"  (or did it say cross sectional area)..

2/0 is 0.364 inches in diameter, so 3/8" OD copper tubing would 
serve, as would some bar stock.




>I decided I'd see how "doable" this standard is on a ham budget. The first
>roadblock I came across was in even finding 2/0 solid. I called one of the
>largest electrical suppliers in the Houston area (think heavy industry,
>refineries, etc) and got a big "huh?" when I asked their wire and cable guru
>about this. He didn't have a clue where one could get such a thing. He also
>offered that he sells plenty of #2 AWG solid tinned for this application,
>but has never been asked about solid 2/0. So maybe it really doesn't have to
>be "solid"..
>
>Further digging resulted in a Wireless Estimator article that indicated the
>"2/0 solid surface area" could be met with the use of 2/0 or 4/0 tinned
>concentric strand. Yet I see respected folks on TowerTalk advise against the
>use of stranded wire in ground service. I guess copper strap could also be
>used if of the appropriate surface area.

I've seen stranded 2/0 and 4/0 used in this sort of application (e.g. 
to bond from the building shell structural steel to a UFER type 
ground in the foundation, and for bonding pieces of the shell together)

But, I've not looked at recent construction, so maybe it's changed.

Jim, W6RMK