Hot Tub on concrete deck

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electricrulez247

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We just did the electrical installation of a Self-contained Hot Tub on a existing concrete porch outside. The deck is 15 feet above grade has a steel frame with metal decking with concrete poured on top. We bonded the steel frame of the deck to the metal frame of the hot tub. Our AHJ had no problem with this, but we talked about if this had been a new concrete deck built to set a hot tub on then the requirements of 680.26(C) Equipotential Bonding Grid would apply. He cited 680.42 Outdoor Installations of Spas and Hot Tubs shall comply with the provisions of Part I and II of this article (680). (we use 2005 NEC)

With that in mind then any time you poured a concrete pad for a Self-contained Hot Tub, either on the ground or an "above grade deck", would require a Equipotential Bonding Grid.

We have been installing the Equipotential Bonding Grid on concrete pads poured on grade for Self-contained Hot Tubs per AHJ. The problem I have with this is the NEC in 680.26(C) is worded and written for a swimming pool. I can't see how to apply this to a Self-contained Hot Tub much less on a above grade concrete deck.

Somebody show me how 680.26(C) applys to a outdoor Self-contained Hot Tub. (in particlar one mounted on a above grade concrete deck)

All of art. 680 needs a major rewrite.
 
Thanks!
I was thinking about this. What problems have occured that caused the NFPA to require an EBG? Is this another skewed statistical proposal?

If it is a genuine problem and needed addressing, then so be it. But if this is another exercise in futility then...

Any substantiation?
 
tshea,
It is because of the stray voltage problems that exist on the power distribution system. At this point, the NEC bonding/grounding rules in 680 actually require that we energize everything that is connected to the bonding/grounding system. This happens because the utility primary and secondary neutrals are bonded together and the voltage drop on the primary neutral shows as a voltage between anything connected to the grounding/bonding system and remote earth. Remote earth is earth outside of the influence of any grounding electrode. This voltage is normally low, less than 5 volts, but in some cases this low voltage combined with a wet body and a large amount of skin in contact with the water has resulted in shocks.
Don
 
Another note about the TIA for 680.26. It does not become enforceable, you will still have to follow the requirements of the 2005 NEC as written, if your jurisdiction has adopted the '05.
The TIA will automatically become a proposal for the next code cycle.
 
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).
Click to expand...

So, looking at this, it appears to me that both the steel supports and the concrete under the hot tub are still required to be bonded. Correct?

Just want to be sure I'm on the same page... :)
 
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