Hot Tub equipotential grid-bonding

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1793

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Louisville, Kentucky
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Inspector
When is it necessary to supply an equipotential grid for a hot tub installed outdoors at a single-family dwelling?

I think the Hot Tub is a factory stand-alone unit.

I look forward to reading replies.

Norb
 
Re: Hot Tub equipotential grid-bonding

The requirement for an equipotential grid for a pool was removed by a TIA last fall.

Regardless of the hot tub being a stand alone unit, heres how the rules in an article apply:
Part I applies to the entire article
Rules in the other parts only apply to that part unless a reference is made to another part.
Part II is permanently installed pools
Part IV is spas and heat tubs

For example look at the rule in 680.70
 
Re: Hot Tub equipotential grid-bonding

Tom:

680.42 refers to Parts I & II and the only equipotential I see mentioned is in Part II at 680.26.

So are you saying that the Equipotential for the Hot Tub is Not necessary?

The requirement for an equipotential grid for a pool was removed by a TIA last fall.
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Re: Hot Tub equipotential grid-bonding

Reference: 680.26 TIA 05-2 (NFPA 70) (SC 05-7-15)/Log No. 821) Pursuant to Section 5 of the NFPA Regulations Governing Committee Projects, the National Fire Protection Association has issued the following Tentative Interim Amendment to NFPA 70, National Electrical Code?, 2005 edition. The TIA was processed by the National Electrical Code? Committee, and was issued by the Standards Council on July 29, 2005, with an effective date of August 18, 2005. A Tentative Interim Amendment is tentative because it has not been processed through the entire standards-making procedures. It is interim because it is effective only between editions of the standard. A TIA automatically becomes a proposal of the proponent for the next edition of the standard; as such, it then is subject to all of the procedures of the standards-making process.

1. Revise 680.26 (C) & 680.26 (C)(1) as follows: (C) Equipotential Bonding Grid. The parts specified in 680.26(B) shall be connected to an equipotential bonding grid with a solid copper conductor, insulated, covered, or bare, not smaller than 8 AWG or rigid metal conduit of brass or other identified corrosion-resistant metal conduit. Connection shall be made by exothermic welding or by listed pressure connectors or clamps that are labeled as being suitable for the purpose and are of stainless steel, brass, copper, or copper alloy. The equipotential bonding grid shall conform to the contours of the pool and shall extend within or under paved walking surfaces for 1 m (3 ft) horizontally beyond the inside walls of the pool and shall be permitted to be any of the following: Exception: The equipotential bonding grid shall not be required to be installed under the bottom of or vertically along the walls of vinyl lined polymer wall, fiberglass composite, or other pools constructed of nonconductive materials. Any metal parts of the pool, including metal structural supports, shall be bonded in accordance with 680.26(B). For the purposes of this section, poured concrete, pneumatically applied (sprayed) concrete, and concrete block, with painted or plastered coatings, shall be considered conductive material. (1) Structural Reinforcing Steel. The structural reinforcing steel of a concrete pool or deck where the reinforcing rods are bonded together by the usual steel tie wires or the equivalent. Where deck reinforcing steel is not an integral part of the pool, the deck reinforcing steel shall be bonded to other parts of the bonding grid using a minimum 8 AWG solid copper conductor. Connection shall be per 680.26(D).

Copyright ? 2005 All Rights Reserved NATIONAL FIRE PROTECTION ASSOCIATION
 
Re: Hot Tub equipotential grid-bonding

So I take it that I would indeed need to construct a grid if this unit is sitting on concrete pavers.

If I read 680.26(5)(C)(3)b.'05 correctly I must make a grid of 12" x 12" #8 bare copper that would extend outward by 3' from the edges of this Hot Tub.
Hot Tub

How deep do I make this grid?

How do you attach each of the intersections? Acorn clamp, Kernies, etc..

As is obvious, this is the first time I've tried to do this.

Thanks in advance

Norb
 
Re: Hot Tub equipotential grid-bonding

shortcircuit2:

Thanks for the link it was very helpful. I hope I have one last question, since this is not a huge installation, would you go ahead and lay the grid under the pavers that the Hot Tub is sitting on and let it extend out beyond as well?

I do appreciate all of the help.

Norb
 
Re: Hot Tub equipotential grid-bonding

1793...it is not necessary to lay the grid beneath the tub so therefore I would not. The materials are quit expensive and I would only install as required...

shortcircuit2
 
Re: Hot Tub equipotential grid-bonding

I'm I missing somthing as the exception does remove the requirment for pools or hot tubs that are made from non-conductive matierals?

Exception: The equipotential bonding grid shall not be required to be installed under the bottom of or vertically along the walls of vinyl lined polymer wall, fiberglass composite, or other pools constructed of nonconductive materials . Any metal parts of the pool, including metal structural supports, shall be bonded in accordance with 680.26(B).
Most stand alone factory hot tubs are made of wood and fiberglass.

And from this requirment it seems to me it's talking about a pool or hot tub formed out of concrete:
The equipotential bonding grid shall conform to the contours of the pool and shall extend within or under paved walking surfaces for 1 m (3 ft) horizontally beyond the inside walls of the pool and shall be permitted to be any of the following
 
Re: Hot Tub equipotential grid-bonding

No Wayne you are not missing anything, you are right on, I agree 110%, and if one looks inside the wiring compartment at the metal within the tub one will see the bonding that is already in place :cool: :cool: .

[ January 24, 2006, 08:42 PM: Message edited by: Jhr ]
 
Re: Hot Tub equipotential grid-bonding

hurk27...I don't interpret the exception that way. The exception was written to clear up the confusion most were having with the original wording which seemed to require the bonding grid under and vertically along the sides of a inground nonconductive pool.

The purpose of the grid is to mask stray voltage where a person would be standing or sitting next to a pool within 3 feet measured horizontally from the inside wall thereby reducing any potential difference.

I don't see where the exception excludes the paved walking surface surrounding a nonconductive pool or hot tub...

shortcircuit2
 
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