equipotential bonding grid under wooden decks?

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Hey Jacques, glad to see you made it on the forum finally.

The issue of the equipotential bonding is a real issue. Two things: First is the tub really on a wooden deck or is it on a concrete foundation that is under the deck. Second , if it is on the deck you better make sure the tub is listed without extra support-- I know in the county one of the boys looks for this.

At the state meeting last year that question arose and one of the cmp (code making panel) members stated it absolutely had to be done. Now how do you do it? That is the trick.

The way the code is written I think the only way to comply would be to have the grid install in the ground under the deck and tub. This could help by making a better contact from deck to grid by running the grid up some supporting posts around the tub.
 
George Stolz said:
I'd say no e-bonding grid/perimeter surface grid required. How do you connect to a wood deck?
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You could staple the wire up the post but I don't think that is necessary. The grid would be in the earth below and could take any potential difference to the ground thru the deck. There is usually some moisture in the decks but I agree it is a bizarre setup and no good way to accomplish this grounding.
 
I was under the impression that the main purpose of the grid is to reduce touch potential in the area to 0v not so much to ground althoug that is a bennifit. If thats the case what good does the grid do if it effectivly in a remote location thats not being stood on. Bondign the gid to an elevate tup (on the deck above) would serve the same purpose as a few ground rods?
 
This was sent to me from a supplier of copper equipotential grids pool related and we had a citation where the inspector wanted the grid under the deck an with 6 in of fill cover dirt on top of it.

Per the 2005 NEC, section 680.26 you are indeed required to have an equipotential bonding grid around the entire perimeter of the pool, whether there is a concrete deck wooden deck or no deck. This is to protect anyone getting in/out of the pool from experiencing stray current. The code reads that you need it 3? going out horizontally from the inside wall of the pool.
 
what i would do then is to install it around the slab 3ft all the way around , if inspector don't like that then i guess you tear the slab out an start new.
 
We got hit on a pool because deck builder showed up 3 days ahead of time an we didn't get the grid in before deck was built an I thought myself why even have it under a deck but I was wrong so the deck guys had to remove quite a bit of deck to install the grid an back fill with 6in of dirt.
 
I have to say the bonding grid under a deck is seems useless but it is in the NEC.
I have a related question. Outdoor spas shall comply with the provisions of Parts I and II of article 680. So what about 680.26(C)? The interior of spas are non-metallic, are you now required to drop a piece of metal in the water in order to have the necessary surface of 9 sq inches of conductive metal in contact with water?
 
Do you think a wood deck is an "unpaved surface"? That would be the only interpretation that would require stringing a piece of copper under it. That doesn't seem right, IMO.
 
Mvillines said:
I have to say the bonding grid under a deck is seems useless but it is in the NEC.
I have a related question. Outdoor spas shall comply with the provisions of Parts I and II of article 680. So what about 680.26(C)? The interior of spas are non-metallic, are you now required to drop a piece of metal in the water in order to have the necessary surface of 9 sq inches of conductive metal in contact with water?
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There is a bond bushing,
I believe it's made by "bond safe" that accomplishes this nicely, I'll se if I can find a link


Here ya go http://www.bondsafe680.com/inground.html Although this is not the bushing I was speaking of,,,they still work
 
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