- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
no-- I guess not, but then it seems totally worthless doesn't it? :grin:
Do you need a bonding grid around a hot tub?
- Thread starter zappy
- Start date
- Status
look at 680.26 (B) (6) (a) 08 NEC
- Location
- Illinois
- Occupation
- retired electrician
I think that the unbonded wet wood is a hazard with a pool where the water is bonded. We are required by the code to energize the water and if we don't also energize the wood or any other type of material that can be touched by a person in the water we have a hazard.
The code needs to be changed to prohibit any electrical equipment of any type that is in contact with the water and the any pumps need to be of the double insulated type. Bonding would still be required for all conductive or semi-conductive items within reach of the water, but any connection, direct or indirect to the electrical system would be prohibited.
The code needs to be changed to prohibit any electrical equipment of any type that is in contact with the water and the any pumps need to be of the double insulated type. Bonding would still be required for all conductive or semi-conductive items within reach of the water, but any connection, direct or indirect to the electrical system would be prohibited.
do you think that a #8 below a wood deck will do anything? I am just trying think what this would accomplish, i agree it is required but will it reduce voltage gradients in the pool area
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
dennis the last part of that section says that where there is no connection between the pool bonding grid and the equipment grounding system, the bonding conductor shall be connected to the EGC of the motor circuit
electricmanscott
Senior Member
- Location
- Boston, MA
electricmanscott
Senior Member
- Location
- Boston, MA
OK. I'll buy into this. If you had a job to install this spa tub are you telling me that you would either lay the grid on the ground or take a sod shovel, lift up a layer of sod, install the grid under it and re-lay the sod ? You can't be serious about this can you
You have no choice but to do this. Just as if it were an above ground pool surrounded by grass.
So, to bond or not to bond, isnt really the question, as much as exactly what to bond? I mean, wet wood is conductive, even if it is dry on the outside surface. How would I bond it? I have bonded concrete pads when they were poured for spas and tubs. Some manufacturers recommend a ground rod, but, most dont even touch the subject and leave as much liability on the "licensed electrician" as possible.
- Location
- Illinois
- Occupation
- retired electrician
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Don, Not sure what you mean by this. How is the water being bonded or energized ? How do you bond the wood, where do you bond it and in how many places do you bond it ? Are deck screws through the floor board to the rafter below considered a mechanical connection ?don_resqcapt19 said:
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Try this experiment - buy an 8' 2 x 4, take a piece of # 12 awg, screw it into one end and plug the other end of the wire into the hot side of a receptacle. On the other end of the 2 x 4 use a meter and measure from the end of the 2 x 4 to any solid ground you can find. Tell us how much voltage you have. If you can't find any unplug the wire, wet down the 2 x 4 and try the experiment againvango said:
That's simple. All deck lumber is now required to come supplied with a # 8 solid pigtail wire to simplify the bonding :grin:
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I was told that you would bond the earth below the deck. Seems strange to me
- Location
- Illinois
- Occupation
- retired electrician
The water is being energized by the voltage drop on the primary and secondary neutrals that provide the building power. The code rules require that the pool bonding system be connected to the building electrical grounding system (the last part of 680.26(B) doesn't really mean what it says, as there is no way to have a bonding system that is not connected to the electrical grounding system if there is any electrical equipment associated with the pool) and this will energize the water. In areas where the utility uses phase to phase connections to the primary of their transformer, there will be very little voltage on the grounding system as you will only have the voltage drop on the secondary neutral conductor, but in areas were a phase to neutral connection is used on the primary of the transformer there will be more voltage. In some cases this voltage will be 5 volts (some studies show that this voltage on the water can make it very difficult for a person to leave the water if the deck is not at the same voltage) or more and the pool water and bonding system will be energized to this voltage. Not you will have to read the voltage to "remote earth" (earth that is outside the influence of any grounding electrode system or bonding system, often defined as 50' or more form any such system).
As far as bonding the wood, I have no idea if it can even be accomplished, however it is my opinion that the code requires it. The most effective bonding would likely be a conductor run on the tops of the joists before the decking is installed.
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Scott, we wouldn't have this forum if the NEC were written so clearly that everyone was able to interpret it in exactly the same way. While I believe the CMP's devoted numerous hours into formulating all sections of the NEC there are some sections that have to be more carefully scrutinized. 680.26(B)(2) is one of those sections.
The language in the 2005 code called for the EPBG to be placed under "paved walking surfaces" whereas the 2008 code calls for the EPBG to be included in "unpaved" surfaces. I'm sure that over 95% of the spa installations we'll all come across will include some type of paved surface. (Is wooden decking considered a paved or unpaved surface ?) However, the OP did mention that the spa tub will be sitting on either soil or concrete. In the case of concrete there's no discussion required. However, in the case of soil you have to just sit back and ask yourself "If I filed under the 2005 code am I going to dig up the sod and lay down a 3' bonding grid under it "? If I filed under the 2008 code am I going to trench down 4" - 6" and lay in a # 8 solid wire all the way around the tub ? In either case, if you gave a price to do the job would you get it knowing that you had to install the grid (labor and material)?
I am of the opinion that section 680.26(B)(2) needs to be revised again and fine tuned. I think the CMP came to the realization that the bonding grid in the 2005 code added more expense to the job than safety benefit and changed that requirement in the 2008 cycle. This section needs to be looked at again and the language changed or made more clear.
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
I'll accept your word for it. Whether you're right or wrong at least you're well spoken on the subject.
I'm sure it gets more complicated if the deck is Trex or Timber Tech.:roll:
- Location
- Massachusetts
As far as the grid being required under grass or soil it is 100% clear, it must have the grid. There is no gray area, the only unclear part is what happens when there is a wood deck.
What does 'unpaved surface' mean to you?:-?
electricmanscott
Senior Member
- Location
- Boston, MA
Commentary from the 2008 handbook....
The requirement for bonding perimeter surfaces now applies to paved and unpaved surfaces. An example of an unpaved surface would be the lawn surrounding a permanently installed above ground swimming pool.
Further along...
Where structural reinforcing steel is not available, a single bare solid #8 AWG or larger copper conductor can be installed around the perimeter of the pool in an area measuring between 18 in and 24 in from the inside pool walls. This 8 AWG bonding conductor can be installed in the paving material or it can be burried in the material below the paving material Where burried, the bonding conductor is not to be less than 4 in and not more than 6 in below the surface level of the subgrade material.
The perimeter surface bonding medium has to be connected at four evenly spaced points around the pool perimeter....
In my view the surafces they are referring to are surfaces of the earth.
I'll eat the page of the code book with pool bonding requirements if someone can proove that the intent of the NEC is to bond a raised wooden deck around a pool or hot tub.
Can anybody even shoe me a proper way to bond a peice of wood?
The requirement for bonding perimeter surfaces now applies to paved and unpaved surfaces. An example of an unpaved surface would be the lawn surrounding a permanently installed above ground swimming pool.
Further along...
Where structural reinforcing steel is not available, a single bare solid #8 AWG or larger copper conductor can be installed around the perimeter of the pool in an area measuring between 18 in and 24 in from the inside pool walls. This 8 AWG bonding conductor can be installed in the paving material or it can be burried in the material below the paving material Where burried, the bonding conductor is not to be less than 4 in and not more than 6 in below the surface level of the subgrade material.
The perimeter surface bonding medium has to be connected at four evenly spaced points around the pool perimeter....
In my view the surafces they are referring to are surfaces of the earth.
I'll eat the page of the code book with pool bonding requirements if someone can proove that the intent of the NEC is to bond a raised wooden deck around a pool or hot tub.
Can anybody even shoe me a proper way to bond a peice of wood?
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