Pool Bonding

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Yes, if the shell is conductive and not separated by a permanent barrier. Refer to 680.26(B(1)(2).
 
Greentagger said:
Yes, if the shell is conductive and not separated by a permanent barrier. Refer to 680.26(B(1)(2).
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Doesn't matter if the shell is conductive or not, you still need the perimeter bond along with the water bond. Only thing different between a conductive shell and nonconductive is you don't have to bond at the 4 points on the pool. Now I'm speaking of the grid or single #8 encircling the pool.
 
Little Bill said:
Doesn't matter if the shell is conductive or not, you still need the perimeter bond along with the water bond. Only thing different between a conductive shell and nonconductive is you don't have to bond at the 4 points on the pool. Now I'm speaking of the grid or single #8 encircling the pool.
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Why does a none conductive shell need a water bond?
 
Little Bill said:
Doesn't matter if the shell is conductive or not, you still need the perimeter bond along with the water bond. Only thing different between a conductive shell and nonconductive is you don't have to bond at the 4 points on the pool. Now I'm speaking of the grid or single #8 encircling the pool.
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Yes sir, you are correct👍
 
mbrooke said:
Why does a none conductive shell need a water bond?
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There’s a case in North Carolina where a 17 year old girl was standing on the pool deck and reached in the water to test the water. They investigated the fatality and found that the equipotential bonding grid was broken.
A fault at the pool pump motor energized sections of the pool. The act of standing on the deck and reaching into the water was fatal because of the potential difference between the two points.


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Peter Furrow said:
There’s a case in North Carolina where a 17 year old girl was standing on the pool deck and reached in the water to test the water. They investigated the fatality and found that the equipotential bonding grid was broken.
A fault at the pool pump motor energized sections of the pool. The act of standing on the deck and reaching into the water was fatal because of the potential difference between the two points.


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So how did the water get energized.
 
Little Bill said:
He said there was a fault in the pump.
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And likely the pump itself either had metal parts touching the water or sections of metal pipe were energized. Also, if part of the equipotential grid was still intact, just isolated from the perimeter grid, then the section of the grid connected to the pump would have energized the water.
In some cases a faulty equipotential grid is more dangerous than none at all. In the same way that under rare circumstances a seat belt worn improperly can be more dangerous than no restraint at all.

In the case of grass surrounding the pool, it would on its own likely be at earth potential, but with the perimeter grid would instead be at the potential of the rest of the pool components, including the water.
 
This chart may help.
As you can see it does not take a lot of current to cause harm.
Even if you are dealing with high resistance/low currents, the potential for harmful currents is there and pools are obviouly an area of increased risk.

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mbrooke said:
Right, but I need help picturing how electricity can travel through piping. At 250 volts we are talking about only 1.55 milliamps...


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Honestly, Voltage or current in the water in the PVC conduit is insubstantial & weak by the time it reaches the swimmer. Highly unlikely that would affect the swimmer because of the voltage gradient dissipates with length.
So I agree with you on that.
However the biggest key factor in swimming pool deaths/electric shock drownings is potential differences. In the case in North Carolina there was a fault in the motor.
The Casing became energized which energized the equipotential bonding system that went around the pool. The equipotential bonding system carried Voltage however there was a break in the bonding system and it was not consistent throughout the grid.
They speculate that the girl was in the water with 120 V ,no problem yet.
However, when she exited on an unbonded ladder she touched a potential difference.
This allowed current to now flow through her and it was fatal. Watch a Mike Holt recent video on YouTube swimming pool bonding july 21 video
Go to the 1:32:00 mark On the video.


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mbrooke said:
Right, but I need help picturing how electricity can travel through piping. At 250 volts we are talking about only 1.55 milliamps...
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What kind of water is in your pipe? Pool water could have salt to generate chlorine. Even just chlorine from a chlorine system may change conductivity compared to tap water or distilled water, as could pH changes.

Underwater metal light niches could become energized, and even worse if part of the bonding grid they are connected to has become energized.

But ultimately I think you're right that bonding the water isn't going to do much good with a typical voltage gradient found in a freshwater pool. May not even trip a GFCI unless some other bonding path is close the where the water is getting energized.
 
suemarkp said:
What kind of water is in your pipe? Pool water could have salt to generate chlorine. Even just chlorine from a chlorine system may change conductivity compared to tap water or distilled water, as could pH changes.
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And some pools use a low concentration of salt to reduce the amount of chlorine that needs to be added to get the desired free chlorine level.
And then there are the seawater-concentration salt pools.
 
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