Equipotential Grid at pools

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dicklaxt

Senior Member
#1.This is presently being hashed over in the NEC forum,,,thats okay

#2.We know that it means the potential from stray voltage at any point on the grid is equal,,,thats okay too.

Now why is it important that this be the case,if we had a point that wasn't bonded to the grid, so what? I'm thinking maybe that if there were a fault at the device that wasn't bonded to the grid then your body becomes the path and that means oops,is this correct?:confused:

dick
 
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dicklaxt

Senior Member
I thought this would generate a bit of interest with all you resi guys doing pools.I still need an asnwer.

dick
 
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dbuckley

Senior Member
Location
Canterbury, New Zealand
The real problem is that with the MGN distribution system used in the 'States there are step potentiasls all over the place, and in a pool situation you are dealing with wet bodies with lowered resistance.

The equipotential grid is a way to get rid of step potentials.
 
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dicklaxt

Senior Member
Once all equipment is bonded together is it then tied to a ground electrode.if it is not, would it hurt to do so or does or hinder/harm the equipotential system itself?

dick
 
George Stolz

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
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dicklaxt said:
Once all equipment is bonded together is it then tied to a ground electrode. if it is not, would it hurt to do so or does or hinder/harm the equipotential system itself?
Click to expand...
The pool itself is connected electrically to the earth extremely well. What harm do you envision transpiring by attaching an additional electrode for fun?

Edit to add: And why would you add that electrode for fun?
 
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dicklaxt

Senior Member
George I am speaking in generallities not just pools.re: what is done at a SubStation?I would think the the close proximety of elect equip being grounded to an electrode ground grid would be adequate to serve as an equipotential grid as well,,,,,,,,,,,not being a SA but curious to the workings,maybe a ground grid would e buried to deep to act as a eq.grid?

dick
 
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dicklaxt

Senior Member
Okay two questions here,,,,,,

#1 Lets say I have bonded all the associated components in and around the pool and it is stated somewhere that you do not need to tie this to a ground electrode but in essence you really are in that the ground wire that runs with the motor feeder to the panel or MCC ground bus is tied to an electrode at the substation and the bond at/from the frame of the motor at the pool.The question was if you tied the bond at the pool proper would it take away from the effectiveness of the equipotential grid?

#2 In this case we are at the substation that has a large ground grid composed of rod electrodes and lets say a 4/0 copper grid and all the equipment at the substation is grounded to this grid,,,,,,,now someone decides that the possible stray voltage from a piece of equipment needs to be dealt with via an equipotential grid so a bonding system is installed and it too is advertently tied to the ground grid via equipment ground buses that are not isolated from their enclosures.I guess I answered my own question their as it evidently can't hurt to tie the two grids together because the way the equipment is built it does it for you.

I hope I made myself clear.

dick
 
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