Equipotential grid for hot tub

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jtester

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Las Cruces N.M.
I have a customer who wants to put a hot tub on an existing porch concrete slab. The slab has a stamped design, and is stained to color it. Looking at the 2008 NEC, 680.42 says the installation must comply with Part II, which requires equipotential bonding including the perimeter, 680.26(B)(2)(a) and (b). Since it is an existing slab, I don't have structural steel available, and can't comply with (b) either because I can't get within or under the perimeter surface.

It seems that it is not permissible to install a hot tub on an existing slab under these conditions.

Has anyone dealt with this before?

Thanks for all your help

Jim
 
You are correct, you are required to have an equipotential bonding grid installed for an outside hot tub. If you have an existing concrete slab you must either replace it and install an Equipotential bonding grid or not install the hot tub on the existing slab.

Chris
 
raider1 said:
You are correct, you are required to have an equipotential bonding grid installed for an outside hot tub. If you have an existing concrete slab you must either replace it and install an Equipotential bonding grid or not install the hot tub on the existing slab.

Chris
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For many people buying hot tubs to stick on their old patio this is a bit of a shocker. I've seen quite a few lately that were installed without permits or inspections solely for this reason.
 
infinity said:
For many people buying hot tubs to stick on their old patio this is a bit of a shocker. I've seen quite a few lately that were installed without permits or inspections solely for this reason.
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I agree, in the 5+ years I have been an inspector I have only inspected 1 new outdoor hot tub install, and that just happend to be because they needed a new service to get enough power to supply the new hot tub.:)

Chris
 
hot tub perimeter surfaces

hot tub perimeter surfaces

in the 2008 nec 680.42 states outdoor tub installations must conform to parts 1 and 2 of art. 680.am i right in thinking a tub installed on a concrete floor in a basement would not have to have the cement floor as part of the equipotential bonding grid?
 
Here in NJ if you install a new hot tub on an existing concrete patio/platform you can use non conductive rubber matts or a wood decking in place of the equipotential bonding grid [ as per 2005 NEC and rehab code]. I have never fully understood the rubber matts, what is a non cunductive rubber matt, how does one install it, what kind of listing should it have, and where would one purchase them? I have gotten different oppinions from contractors and inspectors so the last tub I did I layed down a copper bonding grid mesh and then installed a wooden deck over it.
 
tekelec said:
Here in NJ if you install a new hot tub on an existing concrete patio/platform you can use non conductive rubber matts or a wood decking in place of the equipotential bonding grid [ as per 2005 NEC and rehab code]. I have never fully understood the rubber matts, what is a non cunductive rubber matt, how does one install it, what kind of listing should it have, and where would one purchase them? I have gotten different oppinions from contractors and inspectors so the last tub I did I layed down a copper bonding grid mesh and then installed a wooden deck over it.
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Do you have an official reference that states this?
 
jtester said:
I have a customer who wants to put a hot tub on an existing porch concrete slab. The slab has a stamped design, and is stained to color it. Looking at the 2008 NEC, 680.42 says the installation must comply with Part II, which requires equipotential bonding including the perimeter, 680.26(B)(2)(a) and (b). Since it is an existing slab, I don't have structural steel available, and can't comply with (b) either because I can't get within or under the perimeter surface.

It seems that it is not permissible to install a hot tub on an existing slab under these conditions.

Has anyone dealt with this before?

Thanks for all your help

Jim
Click to expand...

Why not expose the rebar under where the tub is going to be placed?
 
I can agree with the fact that most slabs may not have rebar. I have seen the poured designer slabs that get imprints poured with rebar.

If it does not have rebar, the installer is going to have some explaining to do to the owner...I would like to be a fly on the wall when that happens. :D
 
Pierre C Belarge said:
I can agree with the fact that most slabs may not have rebar. I have seen the poured designer slabs that get imprints poured with rebar.

If it does not have rebar, the installer is going to have some explaining to do to the owner...I would like to be a fly on the wall when that happens. :D
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There is nothing in the building codes that I am aware of that require reinforcing steel in an exterior slab for a patio.

Chris
 
I was told that in Kentucky they are making us saw cut the concrete and insert a ground ring then patch the concrete. I do not have the details of exactly how they expect this to be done, but will if I ever need to install a hot tub on concrete.
 
dhalleron said:
I was told that in Kentucky they are making us saw cut the concrete and insert a ground ring then patch the concrete. I do not have the details of exactly how they expect this to be done, but will if I ever need to install a hot tub on concrete.
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It's best to make the builders or homeowners aware before the pad is poured.
 
Dennis Alwon said:
It's best to make the builders or homeowners aware before the pad is poured.
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We are required to saw cut an existing slab. For example a 40 year old home that someone is now adding a tub. Hopefully we would have the grounding installed properly if the slab and tub were new.
 
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