equipotential bonding grid under wooden decks?

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LYLE2231

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If it's a 120V cord and cap connected I'd say no. Most spas have OEM gfi circuitry built in anyway. I wouldn't consider wood decking a conductor to begin with. Particularly if its above gnd.
 
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Volta

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Jacques Menache said:
Is it necessary to have an equipotential bonding grid under a wooden deck for an outdoor spa? And how to do that after the deck has been built?
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It doesn't need to be a grid if the hot tub has a non-conductive (vinyl or fiberglass) shell 680.26(B)(1).

It can be a single #8 wire, 21" +/- 3" from the inside walls.

The fight would be between 680.26(A) and 680.26(B)(2)(b)(5). The first (A) wants the performance to reduce gradients "in the pool area".

The second (5) specifies sub-grade. No exception given (except rebar :roll:). I would like to see the #8 supported to the bottom of the deck that would seem to meet the overall intent of 680.26(A), but doesn't meet the requirements. Maybe next cycle. :)
 
kbsparky

kbsparky

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Location
Delmarva, USA
This sounds about as useful as grounding a plastic water pipe ... :confused:

What about a spa or hot tub sitting on the top of a deck that is elevated 3 floors up? We have had this type of installation around here in the past ...
 
iwire

iwire

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LYLE2231 said:
If it's a 120V cord and cap connected I'd say no. Most spas have OEM gfi circuitry built in anyway. I wouldn't consider wood decking a conductor to begin with. Particularly if its above gnd.
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OK if you were standing wet and barefoot on a wood deck would you bet your life on the wood being an insulator? :grin:
 
George Stolz

George Stolz

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Windsor, CO NEC: 2017
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kbsparky said:
This sounds about as useful as grounding a plastic water pipe ... :confused:
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That's kinda my thought.

iwire said:
OK if you were standing wet and barefoot on a wood deck would you bet your life on the wood being an insulator? :grin:
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LOL - Well, let's see. I would trust it as an insulator roughly the same as I would trust it as a conductor.

I mean, I was incredulous when the pool water bonding requirement came to be, but now I've become accustomed to the idea. I just can't see the point of attempting to bond wood. I can see banning wood, I suppose, in years to come, because it presents this issue.

The thing is, it seems as though building a wood deck has been the stock answer around here to dodge equipotential bonding around an outdoor spa forever. Now that fundamental attitude is being called into question, I'm not quite sure how to respond to that... :)
 
mikeames

mikeames

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Teacher - Master Electrician - 2017 NEC
George Stolz said:
The thing is, it seems as though building a wood deck has been the stock answer around here to dodge equipotential bonding around an outdoor spa forever. Now that fundamental attitude is being called into question, I'm not quite sure how to respond to that... :)
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Seems like the tail is wagging the dog.
 
electricmanscott

electricmanscott

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Location
Boston, MA
Any body want to take a stab at what Dennis pointed out?


Not sure how this will comply with


680.26(B)(2) Perimeter Surfaces.
(b)(5) The required conductor shall be secured within or under the perimeter surface 100 mm to 150 mm (4 in. to 6 in.) below the subgrade
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