Bonding and Grounding

walkinpool

Gold Supporter
Jul 19, 2019
47
Austin, Texas
I love the discussion here. What do y'all think of this info from reddit that gives some practical examples? Specifically
bonding: ensure no electricity passes through

https://www.reddit.com/r/explainlikeimfive/comments/jig45
Bonding is something that is done to things that aren't supposed to have any electricity at all - usually a metal part that someone will touch. What you can do is use more wires to connect all of the metal parts that people might touch. Then you connect them to the ground.

It's also there to make things safe in another way. Sometimes a wire inside something breaks, and touches the case. If we have bonded the case, then the electricity can jump through the bonding wire and get back to the start. When this happens, a protective device will sense the change and stop the electricity - there are different ways of doing this, but you don't need to worry about it. Without this bonding, and the grounding of one of the wires, then the protective device may not work.
 

ajw22

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Bonding is something that is done to things that aren't supposed to have any electricity at all - usually a metal part that someone will touch. What you can do is use more wires to connect all of the metal parts that people might touch. Then you connect them to the ground.

This explanation was doing fine until .... 'Then you connect them to the ground."

Bonding maintains all the conductive equipment bonded together at equipotential. If you don't understand what equipotential is then you don't understand the purpose of bonding.

The bonding grid does NOT need to he connected to ground to provide equipoetntial. It can do its purpose standalone. Through some of the devices bonded to the bonding grid may be electrically connected to the ground. But that connection is neither required nor the purpose of the bonding grid.

It's also there to make things safe in another way. Sometimes a wire inside something breaks, and touches the case. If we have bonded the case, then the electricity can jump through the bonding wire and get back to the start. When this happens, a protective device will sense the change and stop the electricity - there are different ways of doing this, but you don't need to worry about it. Without this bonding, and the grounding of one of the wires, then the protective device may not work.

This writer does not understand the concept of equipotential bonding.

Nor would they understand why birds can rest on high voltage electrical wires without being electrocuted.
 
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hwy17

Well-known member
Mar 17, 2021
157
Northern California
But that connection is neither required nor the purpose
This is dogmatic. It's not "required", academically and conceptually, for the purpose of bonding.

But it is literally required, you could not design a pool system with an ungrounded bond that would be safe or code compliant.
 

JamesW

TFP Expert
Mar 2, 2011
24,108
Bonding and grounding are both required.

They are separate systems designed to do separate things.

Just because they are "connected" does not really mean anything.

It's mostly irrelevant.
 

walkinpool

Gold Supporter
Jul 19, 2019
47
Austin, Texas
This explanation was doing fine until .... 'Then you connect them to the ground."

Bonding maintains all the conductive equipment bonded together at equipotential. If you don't understand what equipotential is then you don't understand the purpose of bonding.

The bonding grid does NOT need to he connected to ground to provide equipoetntial. It can do its purpose standalone. Through some of the devices bonded to the bonding grid may be electrically connected to the ground. But that connection is neither required nor the purpose of the bonding grid.



This writer does not understand the concept of equipotential bonding.

Nor would they understand why birds can rest on high voltage electrical wires without being electrocuted.

makes sense. Even with the misunderstanding from the author I do like the wording of "Bonding is something that is done to things that aren't supposed to have any electricity at all"
 

ajw22

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I do like the wording of "Bonding is something that is done to things that aren't supposed to have any electricity at all"

Bonding is done to an area so all conductive devices are at equipotential. That area can have electricity and it is safe as long as everything is at equipotential. Bonding is about human safety around electrical equipment.
 

Hadiguy05

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Mar 19, 2021
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Kentucky
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The purpose of bonding is to ensure voltage gradients do not exist in or around the pool. It puts the pool and the area around the pool at equal potential. This is called equipotential bonding (bonding). This keeps people safe while within that equipotential bonding grid. One must be VERY careful to ensure that their isn't a gradient between ground/earth and this bond grid as this could be a very shocking experience. Thus, there becomes a connection back to utility ground as specified by the electrical code to ensure equal potential of the entire system. I won't delve into details of how these connections are made etc.

So, no they aren't the same thing. Lineman used to work between grounds and would still get shocked or worse. It wasn't until the use of equipotential bonding AND grounding were used TOGETHER that Lineman could work safely. This same principle applies for our pools. You must have BOTH to be safe.

Edit
680.26(B) from 2017 NEC says "copper grounding conductor provided to reduce voltage gradients in the pool area shall not be required to be extended or attached to remote panel boards, service equipment, or electrodes."

680.26(B)(6) "Metal parts of electrical equipment associated with the pool circulating system, including pump motors and metal parts of equipment associated with pool covers, including electric motors shall be bonded."
 
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hwy17

Well-known member
Mar 17, 2021
157
Northern California
One must be VERY careful to ensure that their isn't a gradient between ground/earth and this bond grid as this could be a very shocking experience.
This is what I'm saying! The bonded system MUST also be grounded to be safe. Grounding of the bonded system is as important as the bonding.

Further confusion lies in the fact that the NEC code DOES NOT specify that the bonded pool system be connected to the electrical ground. It happens to be impossible to design a code compliant system where it's not because the equipment chassis must be bonded and also connected to the electrical ground, but the lack of any specific mention of this in the pool bonding code gives rise to this confusion that equipotential bonding is somehow completely independent of ground connection. It could be, but if it were it wouldn't be safe.

If you look at any other equipotential bonding code used for bathrooms, livestock pens, or building structures they will require connection of the bonded system to the electrical ground, but the pool equipotential bonding code does not.
 

JamesW

TFP Expert
Mar 2, 2011
24,108
The code actually specifically says that the bonding conductor is not required to be extended or attached to remote panelboards, service equipment, or any grounding electrodes.

However, it does not prohibit connecting the bonding grid to the ground.

I think that the bonding grid in the Canadian code does require that the bonding grid and the grounding be connected but I am not sure.
 

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