Grounded vs. Bonded?
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bphgravity
Senior Member
- Location
- Florida
Re: Grounded vs. Bonded?
Carefuly read the definitions in Section 250.2, then read 250.4(A)(1) and 250.4(A)(3).
As you will see, grounding is for "outside the premise" conditions and plays no role in the normal operation or protection of internal systems. Bonding establishes the effective ground-fault current path, which is a significantly important part of the system operation and safety.
Carefuly read the definitions in Section 250.2, then read 250.4(A)(1) and 250.4(A)(3).
As you will see, grounding is for "outside the premise" conditions and plays no role in the normal operation or protection of internal systems. Bonding establishes the effective ground-fault current path, which is a significantly important part of the system operation and safety.
charlie
Senior Member
- Location
- Indianapolis
Re: Grounded vs. Bonded?
Midget, I am not intending to make this more confusing but the 2008 NEC will change the term grounding conductor to bonding conductor in most places. The purpose is to make it more clear as to what the conductor is used for, bonding parts together for a return path for fault current.
The grounding conductor has nothing to do with grounding except that it is connected to ground in the service equipment. The connection to ground has almost nothing to do with the actuation of the overcurrent devices under fault conditions. You would normally have 500 to 50,000 amperes of fault current flowing in the grounding conductor and 2 to 10 amperes of fault current flowing through the earth.
Midget, I am not intending to make this more confusing but the 2008 NEC will change the term grounding conductor to bonding conductor in most places. The purpose is to make it more clear as to what the conductor is used for, bonding parts together for a return path for fault current.
The grounding conductor has nothing to do with grounding except that it is connected to ground in the service equipment. The connection to ground has almost nothing to do with the actuation of the overcurrent devices under fault conditions. You would normally have 500 to 50,000 amperes of fault current flowing in the grounding conductor and 2 to 10 amperes of fault current flowing through the earth.
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounded vs. Bonded?
Charlie,
Don
Charlie,
You really think that will get through the 2008 code making process? As one of the submitters of that concept for the 2005 code, I would like to see it, but after the exposure in the 2005 code making process, I expect very heavy resistance to the concept. I think that is a change that has long been needed and will help many under stand the concepts. Almost everything that we now call grounding is really bonding.
Don
charlie
Senior Member
- Location
- Indianapolis
Re: Grounded vs. Bonded?
Don, it was accepted in panel 5 on the straw vote but missed 2/3 in the final vote. Several panels accepted the change and it is indeed a viable concept. There was some controversy about it changing some meaning that was not intended and couldn't be fixed in the comment stage. Therefore, a task force is being assembled to study the ramifications and is charged with making a proposal for the 2008 cycle. In my opinion, this time it will make it through the process.
Don, it was accepted in panel 5 on the straw vote but missed 2/3 in the final vote. Several panels accepted the change and it is indeed a viable concept. There was some controversy about it changing some meaning that was not intended and couldn't be fixed in the comment stage. Therefore, a task force is being assembled to study the ramifications and is charged with making a proposal for the 2008 cycle. In my opinion, this time it will make it through the process.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Grounded vs. Bonded?
The Grounding conductor/Grounding Electrode Conductor are usually installed on the supply side of the service disconnect. The equipment grounding conductor (which has been mentioned should be properly called the bonding conductor) is connected on the load side of the service disconnect. 250.4(A)(1)explains why we ground systems, and 250.4(A)(3) explains why we connect the equipment ground conductor(bonding conductor).
The Grounding conductor/Grounding Electrode Conductor are usually installed on the supply side of the service disconnect. The equipment grounding conductor (which has been mentioned should be properly called the bonding conductor) is connected on the load side of the service disconnect. 250.4(A)(1)explains why we ground systems, and 250.4(A)(3) explains why we connect the equipment ground conductor(bonding conductor).
Re: Grounded vs. Bonded?
"Bonding" implies the connections necessary to arrange and effect a monolithic Grounded "stucture" so that all metallic points at any location in a system or installation that could introduce a shock-hazard have a Zero-voltage-to-Ground potential, and that all such points will have a low-impedance path-to-Ground for conducting Ground-Fault currents.
Condider a Sub-panel in a structure de-tached from the structure where the Service is located.All metallic points ( including equiptments) that could possibly become "energized", and all required Grounding-Conductors, must be effectively "Bonded" together to form a monolithic Grounded structure.
In our example, this would require Bonding together the Feeder Equiptment Grounding Conductor, the Grounding Electrode Conductor, the Branch-Circuit EGC's, and the metallic surfaces of enclosures and race-ways.
"Bonding" implies the connections necessary to arrange and effect a monolithic Grounded "stucture" so that all metallic points at any location in a system or installation that could introduce a shock-hazard have a Zero-voltage-to-Ground potential, and that all such points will have a low-impedance path-to-Ground for conducting Ground-Fault currents.
Condider a Sub-panel in a structure de-tached from the structure where the Service is located.All metallic points ( including equiptments) that could possibly become "energized", and all required Grounding-Conductors, must be effectively "Bonded" together to form a monolithic Grounded structure.
In our example, this would require Bonding together the Feeder Equiptment Grounding Conductor, the Grounding Electrode Conductor, the Branch-Circuit EGC's, and the metallic surfaces of enclosures and race-ways.
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounded vs. Bonded?
pattbaa,
Don
pattbaa,
It just doesn't work that way. The grounding connection to earth can never provide a "zero volt to ground (earth) potential under fault conditions. Under fault conditions, everything connected to the grounding and bonding system will have a voltage to earth equal to the voltage drop of the part of the fault return path betweeen the main bonding jumper and the power source.
Statements like this are one of the main reasons the change in wording is required. "Ground fault" currents are not trying to get to ground (earth), they are trying to get back to the power source. We do not need a connection to earth to clear building system faults.
Don
Re: Grounded vs. Bonded?
Don, I hope Charlie is right and your proposal goes through for 2008.
I would also like to add (I know that most here know this but for Midget) that bonding does not have to mean zero potential to any other surface, but rather equal potential, even if this is 12,120,277 v (not necessarily desired though ) or what have you.
If we, or equipment, are at this same potential with protection from being between a surface of another potential, all is well.
Roger
[ December 11, 2004, 02:23 PM: Message edited by: roger ]
Don, I hope Charlie is right and your proposal goes through for 2008.
I would also like to add (I know that most here know this but for Midget) that bonding does not have to mean zero potential to any other surface, but rather equal potential, even if this is 12,120,277 v (not necessarily desired though
) or what have you. If we, or equipment, are at this same potential with protection from being between a surface of another potential, all is well.
Roger
[ December 11, 2004, 02:23 PM: Message edited by: roger ]
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Grounded vs. Bonded?
I also hope the change goes through in the 2008. For example "grounding" a switch could be satisfied by driving a ground rod, which certainly does not satisfy the intent of 404.9
I also hope the change goes through in the 2008. For example "grounding" a switch could be satisfied by driving a ground rod, which certainly does not satisfy the intent of 404.9
Re: Grounded vs. Bonded?
Would that be similar to how when the utility guys want to bare-hand lines they can like hook on to it, and be at the same voltage? I probably didn't explain that right...lolOriginally posted by roger:
Don, I hope Charlie is right and your proposal goes through for 2008.
I would also like to add (I know that most here know this but for Midget) that bonding does not have to mean zero potential to any other surface, but rather equal potential, even if this is 12,120,277 v (not necessarily desired though
If we, or equipment, are at this same potential with protection from being between a surface of another potential, all is well.
Roger
charlie
Senior Member
- Location
- Indianapolis
Re: Grounded vs. Bonded?
I have seen photographs of bare handing 765 kV but our guys don't handle anything over 34.5 kV hot and that is with gloves and a bucket.
I have seen photographs of bare handing 765 kV but our guys don't handle anything over 34.5 kV hot and that is with gloves and a bucket.
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