ECN Forum Forums Code Related Discussion NEC & other Code issues Pool wiring

The #12s are GROUNDS, the #8s are BONDS ... not the same thing, you need both at the light, pump etc. There should be a lug on the pump for the #8 copper.
The "grid" is all of that stuff you BOND together with the #8s. That is pretty much anything metal near the pool or in the water circulation system. That includes your pool and deck steel, ladder cups, diving board stands, the metal pool cage if it is within 5' anywhere, window and door frames in that 5' envelope. In 2005 you are also extending a copper grid in the dirt, 3' out, if you don't have deck steel. If any of the rebar is epoxy coated you need to duplicate it with copper or some other acceptible method. (Say goodbye to coated rebar and pool pavers)
It is imp[ortant to understyand the function of the eqipotential bonding grid is not to ground anything, simply to assure everything is at the same voltage.
It incidentally gets connected to the groundiung electrode system by the equipment grounding conductors via the equipment.

Greg- Your last reply was probably one of the best if not the best capsule statment of wiring a pool/spa and addressing the bonding and grounding needs. If I can only remember it when I run my classes

You could say that. The last time I checked, 1/2" red brass conduit was about $6 a foot.

No wonder deck boxes always used to be flush-mounted, as close to the pool edge as possible.

Has anyone ever had any problems with stray voltage and pools? Or plastic/fiberglass pools and stray voltage?

Harold:
There was/is a situation of stray voltage around my neighborhood in Brick. It was in the Asbury Park Press a few times in fall.

Seems 'they' are saying it's JCP&L/GPU source due to 'single wire earth return' utility transmission system. I don't have a firm grip on it, but something about bare neutral, and grd rods at each pole, neutral 'undersized'; less resistance in/at rod & earth to the pools. One home had >24v at the pool, with the service disconnected.

I have not heard anything over the winter on this, and NO I don't have a pool!!!

John

That is the reason for the equipotential BONDING grid. Even if the pool was 24vac referenced to "something else", everything within 5 feet of the water would be 24v and you would be the bird on the wire. No current would flow through your body.

The more that gets included in your bonding grid, the bigger the safe area would be.

Large ground shifts between adjacent buildings are pretty common here in Florida anyway.

OK...Harold Endean...if the pool is fiberglass with no metal objects to bond, and there is stray voltage in the ground surrounding the pool, can the water in the pool be conductive enough to establish a path for the stray voltage to cause harm to persons using the pool?

shortcircuit

I have seen at least 2-3 problems where there was stray voltage in the area on someones brand new fiberglass pool. In the first instance, the EC asked me how he should bond the pool since there was no metal anywhere. I sad that if he ran a #8 bonding wire all around the pool, he would be safe in case they added anything metal to this pool. A year later I hear that there is about a 10 volt difference between the water and the cement patio around the pool. The EC not only checked the pool, but he checked a iron railing to the front door, a neighbors house, and other metal parts in the neighborhood. He was finding stray voltage everywhere. I am not involved with that town anymore so I don't know the outcome of this job.

Another EC wired a fiberglass pool and I asked him about stray voltage and he looked at me like I had 2 heads. About 2 weeks later I get a call from the EC asking me what he should do about the stray voltage. Long story-short, he installed about 20 ground rods all around the pool with exotermic welded connections and the problem went away. It seems a neighbors house must be having a problem. The reason I say that was because when the new rods where install on the neighbors side, the voltage went away.

I suppose this stray voltage on plastic pools is why they added 680.26(C).
You will be establishing a bonding grid in the dirt if there is no concrete or concrete pool deck rebar. If there is a concrete deck with rebar that should be part of your bonding grid, along with the pump and light so I am not sure why the water would be at a different potential. There is a TIA removing the requirement for a ground mat under a glass pool (the way it reads now) but that may come back if there is still a problem.

gfretwell, what I'm trying to understand is, if the fiberglass pool has nothing to bond (no light or metal objects) and the pools pump is double insulated without bonding, how can there be a potential differance between the stray voltage in the earth surrounding the pool and the water in the pool? I can't see a conductive path in this scenario.

Now...if the pool motor is bonded in the above fiberglass pool installation with no light or metal objects to bond, does the water in the pool create a path for the stray voltage to be harmful to a person useing the pool?

My answer would be no. I would think the resistance of the water would be too high and dangerous levels of current would not flow...?

shortcircuit