Jupe Blue

Does anyone have a good drawing for a layout of an equipotential grid for a new outdoor hot tub install? I'm trying to explain it to a customer and they want a drawing for the guy who will install the concrete pad.

Thanks.

B4T

See if this helps.. http://www.spadepot.com/spacyclopedi...ot-tub-spa.htm

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sbrn33

Does a portable spa need an equipotential grid? Not an inground one but a normal 6 foot by 6 foot above ground tub.

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nitro71

Under the 08 code they do if enforced. You can just put a circle of copper around the tub in the ground. There's the drawing for it.

Dennis Alwon

The 2005 NEC required a mesh type grid for an epb but as others stated a bare copper #8 can encircle the tub using the dimensions in 680.26 (B)(2)(b).

Also if you are under the 2011 NEC there is a TIA that amends the epb under most conditions.

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Jupe Blue

What does TIA stand for? Not coming up with the acronym at this moment.

Dennis Alwon

Tentative Interim Amendment

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Dennis Alwon

You can read it here

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Jupe Blue

Dennis,

Thanks for the info. Did not know there was such a thing as a TIA.

Question: Is the ground (dirt) considered a permanent perimeter surface? Or is that term in relation to structures like a deck or concrete walkway?

The TIA states:


680.42(B) Bonding. Bonding by metal-to-metal mounting on a common frame or base shall be permitted.
Exception No. 1: The metal bands or hoops used to secure wooden staves shall not be required to be bonded as required in 680.26.
Exception No. 2: A listed self-contained spa or hot tub that meets all of the following conditions shall not be required to have
equipotential bonding of perimeter surfaces installed as required in 680.26(B)(2):
(1) Is installed in accordance with manufacturer’s instructions on or above grade.
(2) The vertical measurement from all permanent perimeter surfaces within 30 horizontal inches (76 cm) of the spa to the top
rim of the spa is greater than 28 inches (71 cm).

sbrn33

So like I said. Your normal portable tub installed above grade doesn't need this.
Right?

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Stop trying to think logically, it won't help you here. Just do as we say and everything will be alright.

Jupe Blue

Well I've never installed a bonding grid, but I've only hooked up replacement spas. Question is whether a brand new install would require one. If not required, would it be safer to go ahead and install it?

Would you also be required to bond any re-bar (or wire mesh) in the concrete pad?

B W E

Yes it does. If you look at the handbook, it even uses the above ground package unit in their dimensional drawings.

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Dennis Alwon

I believe it is in reference to either or any surface that is next to the tub.

It depends on what year NEC your area uses. This TIA is only good for 2011 NEC. I think that is a joke but that is what it refers to and in my state that is what I am told. We are under the 2008 still so we must use install the epb. I have also seen many tubs that were set into a deck so that this TIA would not be allowed.

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National Electrical

Standard pool grids are 18"-24" from edge of pool and attached at 4 points of the pool. (aboveground) The same should hold true with a hot tub except for the 4 attachments since most hot tubs are fiberglass. Make sure to attach grid to motor if it is not insulated, along with any other metal objects with in 6 feet. A hot tub is nothing more then a small pool so the same risk is present.