Copper-Conductor Ground Ring
Copper-Conductor Ground Ring
(OP)
I am retired from a weapons-test site where, for safety concerns, every building, bunker and magazine has a ground ring of 4/0-AWG copper conductor directly buried, encircling each—with ¾"x10' copper-clad rods at corners. Early on, {1950s to 1970s} seven-strand conductor was used, but later contractors got away with installing more readily available nineteen strand.
The soil there is immensely corrosive, and concerns are that 19 strand has a greater surface area exposed to corrosive soil than 7 strand. Figure (7/19)^0.5 = 0.61 per-unit—thus 7 strand has 39% less surface area than 19 strand.
My question is, in this application, should 4/0-AWG 7-strand conductor perform appreciably longer than 19 strand?
The soil there is immensely corrosive, and concerns are that 19 strand has a greater surface area exposed to corrosive soil than 7 strand. Figure (7/19)^0.5 = 0.61 per-unit—thus 7 strand has 39% less surface area than 19 strand.
My question is, in this application, should 4/0-AWG 7-strand conductor perform appreciably longer than 19 strand?






RE: Copper-Conductor Ground Ring
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RE: Copper-Conductor Ground Ring
I don't know if the weapon-test site is provided with cathodic protection.
If no cathodic protection is provided the embedded [buried] structure reinforcing steel will be corroded and the entire underground structure will be in danger, namely if it is in a highly corrosive soil. So, I think that using copper bare cables and the copper-clad rods what concerns is the embedded steel corrosion and less the corrosion of the copper surface.
I think copper lead [or tin] covered cable and stainless steel grounding rod will solve both corrosion problems. A new problem will be the connections [better welded and covered also with a moisture resistant material as bitumen or hot shrinking polymer]
See
http://www
As copper lead covered cable supplier may Bayka [Germany]
htt
For welding material may be
http://www.erico.com/products.asp?folderid=41
Also for stainless steel electrodes see:
http://www.erico.com/public/library/fep/LT0359.pdf
As sealant for welded surfaces may be:
RAYCHEM S1061-2-500[hot shrinking]
See:
http://c
BTW:I think that the outer surface of 4/0 cable does not depend so on the number of strands. And if the surface exposed is bigger the current density will be smaller so the corrosion will stay in the same limits.
This is my opinion.
Best Regards
RE: Copper-Conductor Ground Ring
7anoter4, there's no cathodic protection there—just grounding for lightning-air terminals, service-entrance, and diagnostic equipment. Most buildings are under 1500 square feet.
My view is that moisture and dissolved corrosive salts would affect all surfaces on the conductor stranding.
Thanks a lot for your comments.
RE: Copper-Conductor Ground Ring
19 strand conductor has a somewhat lower inductance than 7 strand and thus will be slightly more effective in dispersing high frequency lightning surges into the earth.
RE: Copper-Conductor Ground Ring
RE: Copper-Conductor Ground Ring
Best Regards
RE: Copper-Conductor Ground Ring