Above ground pool bonding

[Mowog]

Hi: We just got a DoughBoy above ground pool. It has a double insulated pump with no grounding lug. Everything except the pool wall is resin/plastic.

Would I benefit by the 8G bonding wire, which would only be bonded to then pool itself? I know I would leave an 8G pigtail in the pump area, but that would not be connected to anything at the present time.

Thanks, Bob

[BigDave]

Do you need, did you get a construction permit to build your pool? My local building inspector was quite specific about the codes we needed to follow which included bonding wire and its attachment to metal pool structures, the pool water and the pump housing.

[Mowog]

Yes, we have a permit. The permit is more specific for "barriers" to prevent people getting into the pool. The electrical section just wants NEC and manufacturers specs followed. Our pump is double insulated and just wants an appropriate outlet/switch, and a GFI. A listened Electrician friend is doing the line to the pump, but scratches his head at a ground wire that goes nowhere.

I've decided to add the 8G ground around the pool while the ground is freshly disturbed, bond it at 4 spots on the pool, add a ground plate to the skimmer, and add a pigtail near the pump for future use (in case someone changes the pump to non double insulated). Total material cost is about $125 additional. This whole bonding thing is confusing, but better safe than sorry- plus being in code always help when we decide to move.

Bob

[BigDave]

That's pretty much the NEC requirement for AG pools as I read it a couple years ago (without the pump bond). I'm still unsure about not including the pump housing in the bonding plan. But, if your electrician friend is betting his license on it ( he did sign the permit? ) then you should be OK - at least as far as the insurance goes. It is good that the bond wire is installed around the pool and bonded to the water.

The only un-bonded pools I've seen have been the Intex variety. Personally, when we had our donut, no one was allowed to touch the pool when it was connected to the electrical supply. Call me crazy but I wouldn't bet the lives of my family on the integrity of the insulation in the pump.

Just my 2 cents.

[PoolDoc]

Bonding and grounding are distinct and different ideas.

Bonding, properly done, creates an equipotential zone in which it is not possible for an uninsulated location to be at a different voltage from another location within that zone. No voltage difference = no potential for an electrical shock. See http://en.wikipedia.org/wiki/Electrical_bonding for a fuller -- if not completely accurate -- explanation.

Grounding involves tying one pole of an AC or DC circuit to the ground or earth. (Grounding is called "earthing" in UK-speak.) Grounding the external case of a motor, tool or other device eliminated the possibility of a voltage difference between the ground you're standing on, and the case of the tool you're working with. Explaining this more fully, and explaining the relationship between a "ground" and the "neutral" is somewhat difficult without getting into AC transformer wiring.

But here are some important points:

1. Both bonds and grounds fail if connections aren't maintained

2. Some allowed NEC methods are, in field practice, very likely to fail.
I personally hate conduit ground (grounds maintained via metal conduit, rather than by a separate wire) because if the conduit gets loose, the ground circuit is broken. I've been badly shocked by equipment that had a 'conduit ground'. Likewise, interrupted pool bond that uses the rebar or some other metal pool element as a primary path for the bonding circuit WILL fail in some pools.

3. I'm not sure what the current situation is, but in the past, the NEC *allowed*, but did not *require*, that the bonding circuit be tied to the grounding circuit. In actual fact, because inground pool pumps are both grounded and bonded, the bonding is grounded, at a minimum, via the pump motor case.
My recommendation is to (a) install un-interuppted bonding, that does not depend on any pool element to complete the circuit, (b) a fully wired ground to and from all exterior electrical panels, (c) a full driven ground rod at each pool panel, and (d) a wired connection between the panel ground and the bonding circuit.

4. But, it's not practical to tie the ground system to the bond field on AG pools using a double insulated pump, and serviced by a 2 wire feeder protected by a GFCI. In this case -- which I understand to be YOUR case -- I would recommend installing a full driven ground rod immediately adjacent to the pool, preferably in the dampest location around the pool, and tying the bonding wire to that ground rod.