indoor pool grounding

[gflux]

New York Code states that "all metallic parts of pool... including the reinforcing metal of pool, coping stones, and decks" must be bonded. Well, the pool and coping stones are bonded. The floor area (deck?) past the coping stone consists of 1 1/2" stone with 2 1/2" of mud resting on a 4" reinforced concrete slab. The stone has not been installed yet. The sub slab reinforcing is welded wire mesh but was not tie wired throughout so it is not a continuous grid.
Could the sub slab really act as a conductor, despite a 4" stone and mud barrier between it and the finish floor level?
We are considering drilling into the sub slab to connect to the mesh reinforcing but we'll never get a real grid and we may unsettle the copings.
Any comments, suggestions? Let the stoning begin.

 

[pierre]

Re: indoor pool grounding

There have been so many situations lately with 'stray voltage', that I believe the Equipotential Bonding of which you are speaking of is more importance than ever. Bonding the decking if you can is a very good idea, especially since wet/moist concrete is hydrostatic and will conduct current very well.
I am surprised you got the inspection without the bonding in place before you ran you wire.

Pierre

 

[jro]

Re: indoor pool grounding

The floor area (deck?) past the coping stone consists of 1 1/2" stone with 2 1/2" of mud resting on a 4" reinforced concrete slab. The stone has not been installed yet. The sub slab reinforcing is welded wire mesh but was not tie wired throughout so it is not a continuous grid.

I'll add this fyi, in part, NEC 2002 680.26 (B) (1)All metallic parts of the pool structure, including the reinforcing metal of the pool shell, coping stones, and deck, shall be bonded. The usual steel tie wires shall be considered sutible for bonding the reinforcing steel.

[ November 14, 2003, 10:56 PM: Message edited by: jro ]

 

[gwz2]

Re: indoor pool grounding

I take gflux 's post as saying the welded wire mesh ' sections' were not tie wired together.

If so, then the 680.26(B)(1) was not ' in compliance '.

gwz2

 

[Guest]

Re: indoor pool grounding

Originally posted by pierre:
<big snip> wet/moist concrete is hydrostatic and will conduct current very well. Pierre

My understanding is that wet concrete is hydrostatic until it sets up. Then it is static. I am familiar with hydrostatic being used with pressure as in hydro-static-pressure. Once concrete kicks it is no longer hydrostatic. Yes, it still contains moisture, but I am not familiar with set up concrete being referred to as hydrostatic.

I know exactly what is being conveyed by the use of the term hydrostatic here, but I'm wondering if it's the right term, or if there is a more specific one?

Mirriam-Webster One entry found for hydrostatic.
Main Entry: hy?dro?stat?ic
Pronunciation: "hI-dr&-'sta-tik
Function: adjective
Etymology: probably from New Latin hydrostaticus, from hydr- + staticus static
Date: 1666
: of or relating to fluids at rest or to the pressures they exert or transmit -- compare HYDROKINETIC
- hy?dro?stat?i?cal?ly /-ti-k(&-)lE/ adverb

 

[gflux]

Re: indoor pool grounding

We've decided to play it safe and we're chopping through the slab to expose the reinforcing and ground it at the expansion joints. This is where we lose our continuous grid.
I'm not convinced though that steel wire 7" below the finish floor could act as a significant conductor.
Thanks for your responses.