Jacussi grounding and bonding

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Re: Jacussi grounding and bonding

This sketch might help illustrate how a voltage gradient is established in the earth surrounding a grounding electrode while it is performing it's intended function.

Ed

Gradient1.gif
 
Re: Jacussi grounding and bonding

If I remember right, I beleive there is or was a stipulation at one point in regard to bonding.

I couldn't quote from where, but I remember that a PORTABLE tub that is listed and has case grounded pumps inside a cabinet designed to not allow easy acces (no hinged doors) was not required to have it's motor cases bonded.

may be way off base, but I want to say a manufacturer told me that.
 
Re: Jacussi grounding and bonding

Ed
I am getting so used to your outstanding illustrations and your excellent posts, that I almost take it for granted, while waiting for your posts. Thank you for your posts.

In addition to Ed's post, I will try to explain what happened at a site this past summer. Refer back to Ed's two posts as they will help alot.


The Utility company was called in to investigate "stray" voltage in their system. It seems that the underground grounded conductor (supplying a condo group) had degraded to a point that the earth was the path back to it's source. In that path was a pool. The people who were using the pool were experiencing shocks as they exited the pool. To make a long story short :) , The stray voltage caused a gradient, and the pool was not properly bonded. As a result, the shocks received by the people. If the pool had an "equipotential grid" set up (proper bonding) they would not have received the shocks, because of the potential of the whole area being the same.

So there are many good reasons for bonding a pool.

Pierre
 
Re: Jacussi grounding and bonding

Originally posted by Ed MacLaren:
This is a difficult thing to explain but I'll give it a try.
Click to expand...
I understand that now. Thanks to both of you for helping me with this.

So, now I ask this: Is everything that is required to be bonded (I have 680.74 in mind) also required to be connected to the equipment bonding conductor, which is connected to the grounding electrode conductor, etc.? Or is the connection of different metals in close proximity the only goal?

Not to denote lack of trust, but code references? :D
 
Re: Jacussi grounding and bonding

is the connection of different metals in close proximity the only goal?
Click to expand...
The bonding together of "non-current-carrying metal parts of electrical equipment" and the "metal parts of non-electrical equipment associated with the pool" is done to minimize the voltage gradients.

However, because the electrical equipment enclosures, which are bonded to the service neutral through the circuit ECG, are included, the #8 "equipotential bonding conductor" is automatically bonded to the panel as well, although it would not need to be to perform it's intended function.

Indeed, during a ground fault in a pool associated circuit, it would be better if it was not connected to the EGC.

Ed

[ January 24, 2005, 10:32 PM: Message edited by: Ed MacLaren ]
 
Re: Jacussi grounding and bonding

Ed
I agree with your statement 100%. I have always thought that it would be better to not have the connection to the ground fault path, just keep it an equipotential grid. I have spoken to many people about this, and the consensus is that it is the lesser of two evils.

Pierre
 
Re: Jacussi grounding and bonding

After giving it some thought, I may have to retract the last statement in my last post.

Any other opinions on it?

Ed
 
Re: Jacussi grounding and bonding

Pierre, I was typing while you were posting. :)

I'm thinking, even if a ground fault raised the voltage on the EGC of a pool-associated circuit momentarily, as long as all of the items connected by the #8 "equipotential bonding conductor" are raised to the same potential, there shouldn't be any hazard.

Ed

[ January 24, 2005, 11:24 PM: Message edited by: Ed MacLaren ]
 
Re: Jacussi grounding and bonding

Wouldn't a barefooted swimmer be electrocuted if they were unlucky enough to be stepping off the grid at the moment of fault? If the grid were grounded the lower impedance of a designed path would assist our victim, wouldn't it?

Edit to add: Suppose it were a fault that was only on the grid. What would open the OCPD, and would our guests ever be able to get away from the pool? :)

[ January 24, 2005, 11:37 PM: Message edited by: georgestolz ]
 
Re: Jacussi grounding and bonding

George this is a good question.
If connected to the equipment EGC then we pose a shock hazard if there is stray voltage from this service at the point where a person could contact the EPB and be standing on Earth bare footed and wet. But if it is isolated from the EGC then it stands the potential of being a shock hazard if a fault was to occur to the EPB via a bonded piece of equipment.

EPB= equal potential bonding

Power company's run their substation grid about 10' past the perimeter of the fence line to prevent this from occurring?

Something to think about. ;)
 
Re: Jacussi grounding and bonding

The substations that we have put grids in for called for a 4/0 bare copper conductor 2' from the fence on the inside perimeter and 3' from the outside of the fence perimeter, ground rods at every corner location also.

The grid also continues for the swing of the access gates.
 
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