"Equipotential grid:" seldom has anything so agitated code issues as much as when this idea was introduced to swimming pools a few cycles back. In 2005 the NEC called for a copper mesh; by 2008 the language had backed off somewhat, to where ordinary steel reinforcing mesh qualified.
The real confusion abounded when the pool deck was something besides concrete; for example, when pavers were set in a bed of sand.
When I did such a pool last year, I went 'beyond' the strict NEC requirements, and actually did use a roll of the copper mesh for the areas adjacent to the pool equipment, and between the pool equipment and the pool itself. My reasoning was that this area was where faults were more likely to develop, and I chose the copper for its' greater corrosion resistance.
That single roll of mesh (3' x 50'), and the associated split-bolt connectors, cost about $850. Net. My cost. It covered about 1/4 of the pool perimeter.
According to the latest IAEI update, this part of the code has been the subject of much discussion by the 2011 panel. It seems that ONE inspector, backed by ONE manufacturer, has instituted some manner of 'appeal' to get the copper mesh requirement included in the 2011 NEC.
This 'appeal' process is a new twist to me! Proposal, committee, vote ... then local adoption / ammendment .... I thought that's how the NEC was made - not by endless litigation funded by deep pockets.
I would say if there was an elevated deck of non-conductive material around the above ground pool, 3 feet out, no grid. If you can stand in the mud and put your hand in the pool, grid. The rule said "paved surface" in 2005, now it just says "perimeter surface" which would include grass/mud. Reno the grid requirement in concrete was rebar, bonded, just like pool steel or you could use the copper mesh, later (2008) reduced to a single #8 ring. The reality is, a single #3 rebar looping the pool might be cheaper that the #8 copper. They also removed the word "bar" so, presumably it could be regular "six over" steel mesh. Ask your AHJ
As I understand it, the specific issue here is not just to have a grid, but to require it to be of copper. The advocate asserts that the single #8 wire that we already have encircling the pool is not adequate.
If you are bonding dirt, it has to be copper. If this is encased in concrete it can be the steel rebar or presumably after 2008, steel mesh.
I understand some people do not think a single #8 is sufficient but Florida decided in 2006-7 that this would work and adopted the 2008 rule early as an addendum. (probably driven by the pool lobby) I am not sure where any of this actually came from and what testing was done to prove the effectiveness but differences in soil material, moisture content and the surface itself would make this testing somewhat useless when any of those changed from the tested media.
It HAS to be copper if you're bonding dirt? Where is that derived from? I spent a considerable amopuntof time with out local AHJ before developing my plan, and we all managed to miss that little detail.
I have also seen companies that sell rubber mats that go all around the hot tub so that you don't have to use the grounding ring. This comes in handy when you set a tub upon an existing concrete patio.