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Old 03-20-2010, 09:50 AM   #61
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Residential - bonding to water lines


So, what were the original intentions when the bonding of electrical systems to the water systems began?

1. Using the water pipes as a connection to earth for stabilizing the electrical system?

or

2. Connecting the water system to the 'grounded conductors' of the electrical system so as to prevent injury to a person should the water system become energized with harmful voltage from the electrical system.

Reference post #49.

Last edited by jlmran; 03-20-2010 at 09:53 AM.
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Old 03-20-2010, 10:02 AM   #62
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Quote:
Originally Posted by jlmran View Post
So, what were the original intentions when the bonding of electrical systems to the water systems began?

1. Using the water pipes as a connection to earth for stabilizing the electrical system?

or

2. Connecting the water system to the 'grounded conductors' of the electrical system so as to prevent injury to a person should the water system become energized with harmful voltage from the electrical system.

Reference post #49.
Connecting to a metallic water pipe that is in contact with the earth for at least 20' establishes part of the grounding electrode system.

Bonding of metallic piping not in contact with the earth such as copper piping coming off of a plastic main is a safety device as you note in #2 above.

The 'grounded conductors' of the system are the neutral conductors as opposed to the 'grounding' conductors.

Last edited by brric; 03-20-2010 at 10:05 AM.
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Old 03-20-2010, 10:17 AM   #63
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By the way, the equipotential grid on a pool is contected to pumps, heaters, etc. which are in turn connected to grounding electrode system via the respective equipment grounding conductors.
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Old 03-20-2010, 10:21 AM   #64
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Quote:
Originally Posted by brric View Post
Connecting to a metallic water pipe that is in contact with the earth for at least 20' establishes part of the grounding electrode system.

Bonding of metallic piping not in contact with the earth such as copper piping coming off of a plastic main is a safety device as you note in #2 above.

The 'grounded conductors' of the system are the neutral conductors as opposed to the 'grounding' conductors.
I stand corrected...should have used grounding instead of grounded. But, you still didn't answer my question, you only restated it. Are there any NEC historians out there?
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Old 03-20-2010, 10:45 AM   #65
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Quote:
Originally Posted by brric View Post
By the way, the equipotential grid on a pool is contected to pumps, heaters, etc. which are in turn connected to grounding electrode system via the respective equipment grounding conductors.
you need to read 680.74. There is no requirement and in fact, there are times where the equipotential grid will not be connected to the equipment grounding conductors.

Any actual connections is purely coincidental and is not required.
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Old 03-20-2010, 11:57 AM   #66
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Just a guess.

The earth is not that great a conductor of electricity. When a ground rod is installed anyway, it is still possible for everything bonded to it to have a voltage difference relative to everything bonded to the water pipe exiting the house, so bonding the water pipe and the ground rod eliminates that voltage difference.

The problem (of two equipotential grids not necessarily at the same potential, or voltage relative to one another) of course does not exist when the pipe is the (primary) grounding electrode.
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Last edited by AllanJ; 03-20-2010 at 11:59 AM.
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Old 03-20-2010, 02:25 PM   #67
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you need to read 680.74. There is no requirement and in fact, there are times where the equipotential grid will not be connected to the equipment grounding conductors.

Any actual connections is purely coincidental and is not required.
That only covers hydromassage tubs.
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Old 03-20-2010, 02:27 PM   #68
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before you even need to deal with that, you need to understand what an equipotential plane is and why it is used.

In very simple terms, it is to establish an area where there will be no difference in potential (voltage) between any two involved conductors. Removing a difference of potential means you will not get shocked regardless of how much voltage (as measured to some other point) is present.

electricity is pretty simple in that matter:

no difference of potential, no current flow.


so, at a pool, in an animal barn, at a cell tower and many other areas utilize an equipotential grid so as to remove the possibility of there ever being a difference of potential between two involved conductors regardless of the source of the voltage.

If you have two or more areas, unless there is a possibility of contacting a point from each of them at the same time, there is no benefit of bonding those two equipotential systems together. It serves no purpose.

that is why a pool equipotential system does not necessarily have to be bonded to the homes GES. While you are at the pool, the only thing you must worry about is getting shocked from is another conductor at the pool area. Only if you can also contact something at the house would the homes GES need to be interconnected.

the earth grounding is not the intent, just the bonding.

and if you want to see a very good yet simple example of why bonding us used, watch this video

High voltage + bonding = no electrocution
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Old 03-20-2010, 02:30 PM   #69
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Quote:
Originally Posted by brric View Post
That only covers hydromassage tubs.
yep, you are correct. refer to 680.26. more rules/ same intent
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Old 03-20-2010, 02:51 PM   #70
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Quote:
Originally Posted by nap View Post
before you even need to deal with that, you need to understand what an equipotential plane is and why it is used.

In very simple terms, it is to establish an area where there will be no difference in potential (voltage) between any two involved conductors. Removing a difference of potential means you will not get shocked regardless of how much voltage (as measured to some other point) is present.

electricity is pretty simple in that matter:

no difference of potential, no current flow.


so, at a pool, in an animal barn, at a cell tower and many other areas utilize an equipotential grid so as to remove the possibility of there ever being a difference of potential between two involved conductors regardless of the source of the voltage.

If you have two or more areas, unless there is a possibility of contacting a point from each of them at the same time, there is no benefit of bonding those two equipotential systems together. It serves no purpose.

that is why a pool equipotential system does not necessarily have to be bonded to the homes GES. While you are at the pool, the only thing you must worry about is getting shocked from is another conductor at the pool area. Only if you can also contact something at the house would the homes GES need to be interconnected.

the earth grounding is not the intent, just the bonding.

and if you want to see a very good yet simple example of why bonding us used, watch this video

High voltage + bonding = no electrocution
Nap - I believe your explanation even applies to those things generally not considered conductors. For example, if the voltage and current associated with rubbing your socks on the carpet and then touching a doorknob were to somehow be identified as hazardous, then there probably would exist a construction code which requires the bonding of carpets to doorknobs!
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Old 03-20-2010, 03:44 PM   #71
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Please read 680.26(B)(6)(a).
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Old 03-20-2010, 03:56 PM   #72
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Quote:
Originally Posted by brric View Post
Please read 680.26(B)(6)(a).
ok

I'm missing your point.
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Old 03-20-2010, 03:57 PM   #73
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Quote:
Originally Posted by jlmran View Post
Nap - I believe your explanation even applies to those things generally not considered conductors. For example, if the voltage and current associated with rubbing your socks on the carpet and then touching a doorknob were to somehow be identified as hazardous, then there probably would exist a construction code which requires the bonding of carpets to doorknobs!
there are places I have been that that would be a welcome addition to the bonding rules
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Old 03-20-2010, 04:09 PM   #74
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Quote:
Originally Posted by nap View Post
ok

I'm missing your point.
680.26(B) saya it does not have to go back to a panel,service equipment, or electrodes. It does not say it isn't supposed to be connected the grounding electrode system.

680.26(B)(6)(a) says that it must be connected to the grounding electrode system by connection to the equipment grounding conductor of the pump motor circuit.
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Old 03-20-2010, 04:29 PM   #75
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Quote:
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680.26(B)(6)(a) says that it must be connected to the grounding electrode system by connection to the equipment grounding conductor of the pump motor circuit.
only under certain circumstances plus it speaks ONLY to a double insulated pump motor and did you catch the part about a replacement motor?

Quote:
680.26(B) saya it does not have to go back to a panel,service equipment, or electrodes. It does not say it isn't supposed to be connected the grounding electrode system.
I never said it couldn't be. I said it is not required to be unless other reasons require it.
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