AG Pool wiring and other headaches

[JohnT]

Okay, I think I have been getting bonding and grounding confused.

You are not alone. Most electricians and pool installers don't get it either.

My pump will be located about eight feet from the pool. Everything that is bonded is supposed to be within five feet of the pool. The only metallic body greater than 4" square within five feet of my pool is the pool itself. Does this mean that bonding isn't necessary, unless I am to bond the different metal parts of the pool to itself?

That is exactly what you do: bond all of the metal pieces together so none can be at a different voltage. You also have to bond any conductive part of electrical equipment that could or does contact the pool water even if not within 5 feet. That would be some pump motors, heaters, SWCs etc..

Also, I keep reading that an earth ground rod is not desirable on a pool circuit, and I am baffled as to why that is the case. This seems to imply that any grounding that takes place is to do so through the residence grounding system. Is this correct?

By pool circuit, do you mean the power circuit for the pool? If so, it is bad practice to ground an electrical system at more than one point. You wind up with current flowing through the earth. Voltage is different at different points, so if you tie them together with a ground system, weird things happen. If you mean the bonding system, the idea is to create that "equipotential plane" which means anything the swimmer can touch is at one voltage. It doesn't matter if that voltage is the same as your house power, because any voltage without a reference is just an arbitrary number. If there is one thing conductive that a swimmer can touch that is at a different potential, then they can be shocked. Grounding just doesn't enter the equation. Adding a ground rod can make the whole mess subject to stray voltage problems. There was a FPN (Fine Print Note) added to the 2005 Code stating "equipotential stray voltage bonding conductors aren't required to extend to any panelboard, service equipment, or an electrode."

You really need to refer to the 2005 NEC. It explains some of this much more clearly than 2002. You may also want to Google for 2008 proposals for 680, as there is more change coming.

Look at Table 680.10 for burial depths. Clearly 18" min inside the 5 foot area.

[The Raddish]

By pool circuit, do you mean the power circuit for the pool? If so, it is bad practice to ground an electrical system at more than one point. You wind up with current flowing through the earth.

As an EE, I understand ground loops. During this whole process I've been trying to bring my EE knowledge with me. I'm not an electrician, but I have done more than a few wiring projects at home. This is the first time I've ever been confused, and I think it is more terminology than anything. Your explanation of bonding in your above post i think cleared up the muddied waters for me.

Getting back to the grounding rod issue, is a grounding rod required at the breaker box for the pool (which is a separate box from the house, but fed from the house box)? I had to return the copy of the 2002 NEC that I had borrowed from a friend, so I don't have access to it any more. I seem to have read conflicting info on the grounding rod for the pool breaker box.

Look at Table 680.10 for burial depths. Clearly 18" min inside the 5 foot area.

All of my underground conduit is greater than 10' away from the edge of the pool. It is nonmetallic, buried at about 14". Everything closer is above ground, attached to the deck structural members.