Sorry for beating a dead horse...

[zappy]

Customer wants to install a hot tub in his backyard. The whole backyard is concreted. Does he have to install a bonding grid? That would be a BIG PITA if that's a yes. Is there another way that would be code, like laying wood down first, and then putting the tub on top? I'm reading 680.42 B, but I don't understand it.

Where also thinking of putting the tub close to the house, so he doesn't have to break up the concrete to run conduit underground to the tub. The disconnect can't be closer then 5' to the tub correct? You can't use more then 6' of flex from the disconnect to the connection on the tub correct? So that only leaves 1' of flex to work with? Is there any way to install a hot tub without having to run pipe underground? Thank you for your help.

 

[Dennis Alwon]

Of course he has to have a bonding grid. You know the code doesn't care what kind of PITA it is.

Correct on the disconnect being more than 5' from the tub but the flex can be longer. I usually use PVC out of the disco and use those couplings with threads on one side, a female coupling, I guess, and go the last few feet with carflex.

 

[WinZip]

Im sure your going to need at least the #8 cu run around perimeter of the tub and here is an idea if all concrete, we did this last summer on a large commercial indoor public pool where they added excise equipment near the pool in five locations an we had to do the bonding on the anchor cups to the basement where the motor's location was.

We came up from below through the concrete deck then used a concrete cut saw and cut out joints between the tile floor 6 inches deep to lay the # 8 cu in then inspected an filled in the cuts with proper compound , this also was approved by the public organization running the pool complex.

 

[satcom]

Lay the copper mesh on the existing paved area where the hot tub will be located, then put the hot tub over the mesh, and install a tile walkway around the tub, you do not have to dig up the existing pad, the tile will also look nice.

Look at the example of installing the mesh http://www.erico.com/public/library/fep/LT1242.pdf

 

[Dennis Alwon]

Lay the copper mesh on the existing paved area where the hot tub will be located, then put the hot tub over the mesh, and install a tile walkway around the tub, you do not have to dig up the existing pad, the tile will also look nice.

Look at the example of installing the mesh http://www.erico.com/public/library/fep/LT1242.pdf

I am not sure that would pass code. The NEC 2008 calls for the copper (no mesh needed) needs to be 4-6 inches below subgrade. I don't think what you state will work well at all. My assumption is below the reason for grade is that the moisture in the soil helps.

FWIW, I heard that the 2011 has gone back to the mesh but I have not checked it yet--

 

[satcom]

I am not sure that would pass code. The NEC 2008 calls for the copper (no mesh needed) needs to be 4-6 inches below subgrade. I don't think what you state will work well at all. My assumption is below the reason for grade is that the moisture in the soil helps.

FWIW, I heard that the 2011 has gone back to the mesh but I have not checked it yet--

Dennis, I understand what you are saying, we have a serious problem with pools and stray power in my area, some people can't use their pool it is so bad, and after years the only fix the utility can come up with is to create a plane around the pool, the mesh issue is an interesting subject.

 

[WinZip]

Dennis, I understand what you are saying, we have a serious problem with pools and stray power in my area, some people can't use their pool it is so bad, and after years the only fix the utility can come up with is to create a plane around the pool, the mesh issue is an interesting subject.

Satcom , I have seen in ground metal wall pools just eaten away from stray currents in the earth - pool light fixture trims - ladder cups anything metal just deteriorated from stray currents even when properly bonded.

 

[Dennis Alwon]

Here is an excellent thread-- at least toward the end-- on transient voltages. The thread is called 5 volts between pool and patio

 

[zappy]

Of course he has to have a bonding grid. You know the code doesn't care what kind of PITA it is.

Correct on the disconnect being more than 5' from the tub but the flex can be longer. I usually use PVC out of the disco and use those couplings with threads on one side, a female coupling, I guess, and go the last few feet with carflex.

Flex can be longer then 6'? What is 680.42 A (1) talking about then?

 

[Dennis Alwon]

Flex can be longer then 6'? What is 680.42 A (1) talking about then?

My mistake.. I read that as longer than 6'. What is the difference if you can use PVC???? I guess the flex is more subject to damage. I know I have broken that rule once but as I said I generally run rigid PVC to the unit and then flex into it.

 

[kwired]

Dennis, I understand what you are saying, we have a serious problem with pools and stray power in my area, some people can't use their pool it is so bad, and after years the only fix the utility can come up with is to create a plane around the pool, the mesh issue is an interesting subject.

Stray voltage is nothing new to dairy farmers. The issue comes primarily from poor or deteriorated grounding or improper installations. The source can be a loose connection on a utility structure (primary or secondary), or from a problem at a neighbors property. The fact that utilities as well as consumers use grounded conductors as current carrying conductors and drive ground rods and bond to other electrodes at every structure introduces the possibility of many places for current to travel when a connection fails someplace.

The best thing is to not intentionally have current on grounded conductors, but how do you change this basic practice that has been in place pretty much ever since AC current was first used?

 

[zappy]

Ok so you lay in the grid. Then you bond it to the motor housing hot tub, and that's it? Isn't everything double insulated in a hot tub?

 

[Dennis Alwon]

Ok so you lay in the grid. Then you bond it to the motor housing hot tub, and that's it? Isn't everything double insulated in a hot tub?

Doesn't matter there should be a lug on the motor. I am not sure whether all tub motors are double insulated. If there is no lug then just bring it to the motor area in case the motor ever gets changed out.

Which code cycle are you on???

Here is the 2008 statement-- very different for the 2005.

680.26 (B)(6)(a) Double-Insulated Water Pump Motors. Where a double-insulated water pump motor is installed under the provisions of this rule, a solid 8 AWG copper conductor of sufficient length to make a bonding connection to a replacement motor shall be extended from the bonding grid to an accessible point in the vicinity of the pool pump motor. Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit.

 

[satcom]

Ok so you lay in the grid. Then you bond it to the motor housing hot tub, and that's it? Isn't everything double insulated in a hot tub?

not just the Code, you will need to follow the manufactures instructions, and requirements, and check with your AHJ to see if the grid plane your are going to install will meet all the requirements.

 

[zappy]

Doesn't matter there should be a lug on the motor. I am not sure whether all tub motors are double insulated. If there is no lug then just bring it to the motor area in case the motor ever gets changed out.

Which code cycle are you on???

Here is the 2008 statement-- very different for the 2005.

Thanks Dennis. Where on 2005.

 

[Split Bolt]

Ditto. Run PVC to near the unit, glue a female adapter onto the PVC and screw the LT connector into the female adapter.

 

[zappy]

This bonding grid stuff & stray voltage is new to me. Got some questions.

This bonding grid stuff & stray voltage is new to me. Got some questions.

1.OK, so this is about stray voltage from a outside source, not from anything on your property?

2.So I'm getting out of the hot tub, one foot is in the water, one is on the concrete. Is that when the trouble starts? What if you get out of the hot tub with two feet?

3.What if you have stray voltage coming from who knows where, your dripping wet, you step from the inside of your house, onto the concrete outside. Would you get shocked?

4.Isn't concrete's resistance higher then the copper mesh under it? So how are you at the same potential then the water?

5.Correct me if I'm wrong please, the only way you can get shocked is if your between the path of electrons back to the source. So why not lay a rubber mat around the perimeter, or wood.

6.Can someone die from 5V of stray voltage?

7.What if you have 5v. of stray voltage from one phase, and a voltage leak from in the hot tub on a different phase? Would you get shocked?

Sorry for all the dumb questions

 

[kwired]

1.OK, so this is about stray voltage from a outside source, not from anything on your property?

2.So I'm getting out of the hot tub, one foot is in the water, one is on the concrete. Is that when the trouble starts? What if you get out of the hot tub with two feet?

3.What if you have stray voltage coming from who knows where, your dripping wet, you step from the inside of your house, onto the concrete outside. Would you get shocked?

4.Isn't concrete's resistance higher then the copper mesh under it? So how are you at the same potential then the water?

5.Correct me if I'm wrong please, the only way you can get shocked is if your between the path of electrons back to the source. So why not lay a rubber mat around the perimeter, or wood.

6.Can someone die from 5V of stray voltage?

7.What if you have 5v. of stray voltage from one phase, and a voltage leak from in the hot tub on a different phase? Would you get shocked?

Sorry for all the dumb questions

The purpose of bonding conductive items together is to ensure that they are all at the same potential in relation to each other, this will prevent getting a shock or electrocuted. You may have a bad neutral on the service and the voltage on all bonded items to a point ahead of the bad neutral will be higher than usual but all items bonded together will have no potential between them.

Earth and concrete is not as good of a conductor as metal objects but it normally conducts well enough to be dangerous. Bonding grids, mesh, and other electrodes are an attempt to make the area they are protecting to be much closer to the same potential as the other grounded objects in the area.

 

[cadpoint]

It doesn't matter what the answers are that are given here if you don't involve the AHJ before you think you know or understand what they want all else is a void... The NEC is the minimun(sp), if you haven't met it then, well you haven't...