Proper Pool/Spa Bonding

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  #1  
Old 10-05-07, 03:15 PM
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Proper Pool/Spa Bonding

I Just installed a pool/spa subpanel and heat pump with help from this forum, thank you.

I am questioning the bonding method used by the pool/spa company and maybe i can enhance it with the addition of the subpanel.
I have not (yet) changed their bonding method with the addition of the subpanel.

The pool and spa rebars/mesh are all bonded together with solid insulated 8ga green wires running over to the pump area in the dirt. The aluminum screen porch bonding wires do the same.

At a single point in the dirt next to the pump slab all the bonding wires tie together. The only ground source is the solid 12 ga wire running to the pool pump housing.
There are no ground rods near this area.

It seems strange that all these bonding wires are thick running to this point in the dirt and the only ground source to this point is a tiny 12ga wire which uses the pump housing as part of path to the pumps green supply ground wire from the sub panel, also 12ga.
Is this Acceptable?

Should I run a 6ga solid insulated green wire from the subpanels grounding block to the point in the dirt where they all come together?
... and eliminate the 12ga bonding wire to the pump housing (the pump housing will continue get its supply ground from the sub panel).

This would at least ensure a direct path back to the main panel ground.

Thanks, Glenn
 
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  #2  
Old 10-05-07, 04:34 PM
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You are very much confusing bonding with grounding.

Bonding is what the pool guys did, just not very well unfortunately.

You DO NOT need or want to connect to a panel ground. You are NOT "grounding" anything. That #12 is NOT a "ground source". It is the motor bond, but it is MUCH too small.
You DO NOT need or want to install ground rods for the bonding.

Bonding is simply connecting EVERYTHING metallic associated with, or near, the pool so that it is all at the same potential. This is NOT done so that a breaker will trip in case of a short.

The main thing you need to correct is that #12 to the motor. ALL pool/spa bonding is done with a SOLID #8cu. You can use #6 but it is totally unnecessary.
 
  #3  
Old 10-05-07, 04:37 PM
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Here is some good reading. Taken from the NEC Handbook:

It is important to understand the difference between the terms bonding and grounding as they apply to Article 680. As defined in Article 100, bonding is ``the permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.'' As described in 680.26(A), the function of equipotential bonding differs from the function of bonding to meet the requirements of Article 250 in that providing a path for ground fault current is not the function of the equipotential bonding grid and associated bonding conductors.
Creating an electrically safe environment in and around permanently installed swimming pools requires the installation of a bonding system with the sole function of establishing equal electrical potential (voltage) in the vicinity of the swimming pool. A person who is immersed in a pool or who is dripping wet, has a large amount of exposed skin, and is lying or walking on a concrete deck is extremely susceptible to any differences in electrical potential that may be present in the pool area.
The primary purpose of bonding in and around swimming pools is to ensure that voltage gradients in the pool area are not present. The fine print note explains that the 8 AWG conductor's only function is equipotential bonding to eliminate the voltage gradient in the pool area.
The reason for connecting metal parts (ladders, handrails, water-circulating equipment, forming shells, diving boards, etc.) to a common bonding grid [pool reinforcing steel, pool metal wall, or an alternative bonding grid as described in 680.26(C)(3)] is to ensure that all such metal parts are at the same electrical potential. The grid reduces possible injurious or disabling shock hazards created by stray currents in the ground or piping connected to the swimming pool. Stray currents can also exist in nonmetallic piping because of the low resistivity of chlorinated water.
 
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Old 10-05-07, 08:57 PM
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All that #8 For the BOND should be bare.Or at least stripped back to bare and mechanicaly connected to the mesh and other metalic parts.

again this BOND will not connect to the GROUND conductor.
 
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Old 10-05-07, 09:03 PM
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Wink

Have you check what code there calls for first????
 
  #6  
Old 10-10-07, 09:49 AM
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My main question is: Should I connect the concrete mesh, rebar, aluminum porch wires to the sub panel ground bar within in the sub panel?

I am very surprised the NEC Handbook section mentioned earlier did not discuss galvanic reactions of the rebar and mesh within the pool spa environment and the use of bonding to prevent it.
The last thing you want is for the rebar or mesh to corrode because of stray currents thereby cracking the concrete and pool walls.

Isn't it true that when grounding is used to prevent galvanic reactions they call it "bonding" and when the grounding is used for safety then it is called "grounding"?

If I have interpreted correctly what was said so far: Tie all rebar, mesh, aluminum porch metal together so they are all at the same potential however this might not be at ground level relative to the power panel?
I can't imagine this could be correct.

The normal currents through the bonding wires have to be very small maybe mA or uA but they specify using large wire size. Is this because they want the lowest resistance in the wire run so the voltage difference from one end to the other is very low?

Thanks for all the input. Glenn
 
  #7  
Old 10-10-07, 10:05 AM
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Do not directly connect your bonding grid to the sub panel. That would be wrong.

When you bond all the metal together and connect to the pump connection, you address the problem.



Originally Posted by Glenn111 View Post
Isn't it true that when grounding is used to prevent galvanic reactions they call it "bonding" and when the grounding is used for safety then it is called "grounding"?
No. One is bonding, the other is grounding. Grounding is not bonding. Bonding is not grounding.
 
  #8  
Old 10-10-07, 10:47 AM
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Bob,

Ok, I will NOT connect directly to the subpanel ground.

Sorry for my confusion on this. Thank you for your patience.

However the way it is presently, might be wrong then.

The pump housing is grounded via the supply wires, 2 blk & 1grn 240V. The grn wire bolts directly to the housing.

The bonding wire node connects to the pump house therefore the bonding wires are now grounded.

Is this what you meant by problem addressed i.e. grounding made indirectly via the grounded pump housing?

Should the bonding node not be connected to the grounded pump housing?
 
  #9  
Old 10-10-07, 01:34 PM
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Numerous building code websites have this requirement in their documents.

E4104.1
"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."

So how is this considered not grounding the bonding grid? Which was indicated as the wrong thing to do in previous threads.

The equipment grounding conductor of the motor circuit is the grn wire from the panel which they say to connect the bonding conductor, right?
 
  #10  
Old 10-10-07, 01:50 PM
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If you connect the bonding grid directly to the sub panel ground and to the motor, then you have two paths. Not good.

If you connect the bonding grid to the sub panel ground and NOT to the motor then the motor is not bonded to the other metal. Not good.
 
  #11  
Old 10-10-07, 02:43 PM
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The previous messages confused me when they said whatever you do, don't ground the bonding grid.

Mine is grounded as follows:

The main panel grounds the subpanel, the subpanel grounds the pool pump housing, the pool pump housing grounds the bonding grid.

This configuration is pretty much exactly what the various county building code documents E4104.1 say to do.

The bottom line is the bonding grid is supposed to be grounded but in a specific correct way, right?
 
  #12  
Old 10-10-07, 02:57 PM
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Originally Posted by Glenn111 View Post
The bottom line is the bonding grid is supposed to be grounded but in a specific correct way, right?
Yes, but you have nothing (or at least very little) to do with this.
 
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