EGC vs EBC term wise

[blue spark]

I remember Mr. Holt discussing this once and it's starting to sink in with me. The GEC is the conductor that connects our AC systems to ground. We all know that. However, it really starts to get confusing in 250 when the term "grounding conductor" starts getting thrown all over the place. It seems to me anything other than the GEC that brings all electrical components into the same potential should be a bonding conductor. ie "Bonding Jumper". Am I lost on this or missing something? Isn't the EGC really just a bonding conductor to the grounding system? I've heard rumors that 250 is going to have some radical changes in 08. Hope that's one of them.

 

[roger]

You are correct that there is unnecessary confusion caused by the terminology.

Don, AKA don_resqcapt19 has been proposing this change for years but the CMP's have remained reluctant to accept his proposals.

Roger

 

[bphgravity]

The 2008 NEC will change all the sections that state, "shall be grounded" to "shall be connected to an equipment grounding conductor". Though not a perfect fix, it does clear up the intent and makes the requirement for "grounding" equipment a little less confusing.

 

[jwelectric]

Define equipment grounding conductor

250.4 General Requirements for Grounding and Bonding.
The following general requirements identify what grounding and bonding of electrical systems are required to accomplish. The prescriptive methods contained in Article 250 shall be followed to comply with the performance requirements of this section.
(A) Grounded Systems.
(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
(2) Grounding of Electrical Equipment. Non?current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.

 

[don_resqcapt19]

Mike,
You need to go on to part 5 of that section...that is the real function of the EGC.

(5) Effective Ground-Fault Current Path Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.

Also under fault conditions it cannot accomplish item 2 as at the voltage at the faulted equipment will rise above earth to a voltage that is equal to the voltage drop on the equipment grounding conductor. This can often be more than 50 volts. This voltage will exist until the fault is cleared.
Don

 

[jwelectric]

Don

The original poster has asked a question about the ?Equipment Grounding Conductor.?
He seems to think that the name of this conductor should be changed to the Equipment Bonding Conductor.

I was pointing out that the requirement found in 250.4(A) (1) and (2) requires that all metal parts enclosing electrical components is to be connected to earth.
This is accomplished with a conductor named for doing just this it is called the ?Equipment Grounding Conductor.? (Grounding meaning connecting to earth)

I agree that this connection to earth will play no part in the operation of the overcurrent device but as long as 250.4(A)(1) and (2) remain part of the requirements of the NEC then I think that the name of the conductor that accomplishes this should remain the same, Equipment Grounding Conductor.

 

[don_resqcapt19]

Mike,

He seems to think that the name of this conductor should be changed to the Equipment Bonding Conductor.

As do I and the majority of the members of CMP5. My proposal to make this change was accepted by a vote of 8 to 4, but had to be reported as reject becuase the NFPA rules require a 2/3s vote to make a code change.
The connection to earth is a very minor function of the equipment grounding conductor. Its main and most important function is that of a bonding connection back the the main bonding jumper to provide the fault clearing path. In my opinion, the only conductors that should use the word grounding are conductors that have one end connected to a grounding electrode. All of the other conductors that we now call grounding conductors should become bonding conductors. The use of the term bonding is what leads many to think that as long as we have a connection to the earth the system is safe. One common example is parking lot light poles, many, both engineers and electricians, think that if they provide a grounding electrode at each pole that they can eliminate the EGC back to the supply. They are lead to think this because of the use of the word grounding in the term equipment grounding conductor. If the term were to be changed to equipment bonding conductor it would more correctly describe the function of the conductor and help eliminate the problems that occur in the field.
Don

 

[jwelectric]

Don I agree with everything that you say

But

There remains a rule that requires all of this equipment to be connected to earth.

In my opinion we will need to squelch the rule to connect all this metal to earth before the name of the conductor will ever be changed. I could be wrong with my thinking and the name get changed anyhow.

 

[don_resqcapt19]

Mike,

In my opinion we will need to squelch the rule to connect all this metal to earth before the name of the conductor will ever be changed.

I don't think that rule will ever go away, but it does not require a direct connection to earth and that is what the word grounding implies.
Don

 

[jwelectric]

In my opinion we will need to squelch the rule to connect all this metal to earth before the name of the conductor will ever be changed.

Mike,
I don't think that rule will ever go away, but it does not require a direct connection to earth and that is what the word grounding implies.
Don

If we look closely at 250.4(A) (1), (2) and (3) we can see that something started a long time ago still has a hand hold today and there is a reason for this not being easily changed.
In (A)(1) we are simply told that if the service has a grounded (neutral) that this conductor is to be terminated to earth some where between the point of attachment and the first overcurrent device. I think that we both agree here.

In (A)(2) the water gets a little muddy.

Grounding of Electrical Equipment. Non?current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.

Here we are told that the ?grounding? conductor that is connected to equipment is to be terminated to good old mother earth.
This seems to cause confusion due to the bonding issues as covered in 250.4(A)

(3) Bonding of Electrical Equipment. Non?current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.

An easy fix to this confusion to connect the Equipment Grounding Conductor to earth or to the Grounded (already connected to earth which is what we are doing anyhow) would be to delete 205.4(A)(2) or revise it to state to the grounded (neutral) when available.

BUT

Then what would we do with 250.4(B)?

 

[blue spark]

The 2008 NEC will change all the sections that state, "shall be grounded" to "shall be connected to an equipment grounding conductor". Though not a perfect fix, it does clear up the intent and makes the requirement for "grounding" equipment a little less confusing.

Wise and Welcomed.

 

[Bob NH]

Mike,
As do I and the majority of the members of CMP5. My proposal to make this change was accepted by a vote of 8 to 4, but had to be reported as reject becuase the NFPA rules require a 2/3s vote to make a code change.
Don

Does CMP5 have a different kind of arithmetic than the rest of us. In my new 704-page Robert's Rules of Order Newly Revised a two-thirds vote is defined as two-thirds of the votes cast, excluding blanks and abstentions. It isn't "two-thirds + 1" as in a majority vote requirement. There is no such thing as a tie in two-thirds voting.

 

[dnem]

The terminology used in the code book can be debated over what would be the best word to use but ultimately we have what we have and I fall into the category of making the best with what we have.

What we have is a code book that has bastardized the word "ground" and left its usefulness minimal. . I think we would be better to just accept that the NEC uses "ground" to refer to both bonding and connection to earth.

Equipment Grounding Conductor = Equipment Grounding/Bonding Conductor
Electrode Grounding Conductor = Electrode Grounding/Earthing Conductor

You just have to automatically think of bonding when you hear equipment
and think of earthing when you hear electrode.

David

 

[jwelectric]

You just have to automatically think of bonding when you hear equipment
and think of earthing when you hear electrode.

David

David

Help me out a little here as I am thinking about an Ungrounded Delta system.
How and where do I bond the equipment grounding conductor at the service?

 

[don_resqcapt19]

Bob,
The correct vote was 9 to 7 with 16 members eligible to vote, so it would have needed two more votes not just. I should have looked at the 2005 ROP before posting. Sorry for the confusion.

In my new 704-page Robert's Rules of Order Newly Revised a two-thirds vote is defined as two-thirds of the votes cast, excluding blanks and abstentions.

The NFPA has their own rules and requires a 2/3s vote of all panel members that are eligible to vote. They do not exclude blanks and abstentions.
Don

 

[dnem]

David

Help me out a little here as I am thinking about an Ungrounded Delta system.
How and where do I bond the equipment grounding conductor at the service?

I remember years ago, during apprenticeship 101, learning about the "star" point which was the single bonding point connection for 5 items [It became a modified star when I found out you could bond the electrode to the meterbase]. . The 5 items of the star at the service disconnect are:
1] Service neutral [or grounded phase for corner grounded delta]
2] Load neutral conductor or bar
3] Electrode grounding/earthing conductor(s)
4] Equipment grounding/bonding conductor, conduit, or bar
5] Service disconnect enclosure

So getting to your question:
"How and where do I bond the equipment grounding conductor at the service ?"

If the system has all 5 items, bond them all at the main disconnect.
If the system only has items 3, 4, + 5, then bond them and you're done.
The bonding attached to the service disconnect enclosure is not voided by the absence of a neutral.

David

P.S. Since I know that you already knew everything that I posted, I'm now waiting to find out why you asked me to answer that question.

 

[jwelectric]

Just what is 3 and 4 above?

Are they REQUIRED to connect to earth?

In an ungrounded Delta system is there a bond to the service grounded conductor? Is there a service grounded conductor?

Does the equipment GROUNDING (earthling) conductor not connect to the earth here?

 

[dnem]

Just what is 3 and 4 above?

Are they REQUIRED to connect to earth?

In an ungrounded Delta system is there a bond to the service grounded conductor? Is there a service grounded conductor?

Does the equipment GROUNDING (earthling) conductor not connect to the earth here?

?Just what is 3 and 4 above??

3] Electrode grounding/earthing conductor(s)
4] Equipment grounding/bonding conductor, conduit, or bar

I can?t answer the question of ?what is? it because I don?t understand what you?re asking.

?Are they REQUIRED to connect to earth??

You know that they are, so what are you asking about ?
250.52(A)(1)+(2) even specifies that the ?direct contact with the earth? must be at least 10?
250.52(A)(3)+(4) specifies 20? of earth contact
250.53(G) has an 8? ?in contact with the soil?
You know these rules and there?s nothing more I can add so once again, I don?t understand what you?re asking me to add.

?In an ungrounded Delta system is there a bond to the service grounded conductor? Is there a service grounded conductor??

No and No

?Does the equipment GROUNDING (earthling) conductor not connect to the earth here??

250.4(B)(1)
Yes, it connects the equipment to earth thru its connection to the electrode system. . Grounding and grounded are two different things. . The absence of a grounded conductor does not affect the grounding conductors requirements. . The electrode earthing handles lightning and the equipment bonding handles overcurrent to allow the OCPD to operate.

The only difference is that the equipment bonding operates OCPD on the first fault in a grounded system but not until the second fault on an ungrounded system. [250.4(B)(4)]

The ungrounded system has no ?star?. . It only has 3 points. . It connects electrode earthing, equipment bonding, and enclosures so there?s no connection to the transformer to operate OCPD on the first fault. . The first fault grounds the system, grounds the transformer coil/windings and allows for OCPD operation on the second fault.

The lack of response of the ungrounded system to the first fault shows the response of an improperly grounded grounded system. . The ?response? of the improperly grounded grounded system is to continue to operate equipment and sit there and wait until a person touches a certain piece of metal. . It?s like a loaded gun except you don?t even know it?s there waiting for you.

David

PS We lost the requirement for ground detector lights in 1999NEC, didn?t we ?

 

[jwelectric]

The point that I am trying to make is simple to see if you will slow down and see it,

The requirement found in 250.4(A)(2) or the requirement that the equipment grounding (earthing) conductor to connect the metal part of the system to earth is there for the inclusion of the ungrounded Delta system.

To change the wording of the NEC or to start training people that the equipment grounding (earthing) conductor is anything else other than a conductor that connects to earth would mean that the ungrounded Delta system would now be required to have a grounded (earthed) conductor installed. When this happened the ungrounded Delta system just became a grounded Delta.

We need to teach that it is through the main bonding and system bonding jumpers that the system is interconnect so that fault current returns to the source.

 

[dnem]

Now I'm starting to understand what you're up to. . And now that I know, the first thing I need to do is correct something that you said that I overlooked before. . I considered correcting it before but I thought it would derail the subject.

But it won?t derail the subject. . It?s central to the subject.

To change the wording of the NEC or to start training people that the equipment grounding (earthing) conductor is anything else other than a conductor that connects to earth ?..

I?ve never spoken about an ?equipment grounding (earthing) conductor?. . I?ve always linked equipment with bonding. . And I?ve linked electrode with earthing.

The equipment bonding is the fault current OCPD operation part of the grounding system.
The electrode earthing is the part of the grounding system that keeps all of the metal parts at the same potential as the earth so as not to attract lightning. . If the system is electrically identical to earth, there?s nothing to attract lightning to the system.

To change the wording of the NEC or to start training people that the equipment grounding (earthing) conductor is anything else other than a conductor that connects to earth would mean that the ungrounded Delta system would now be required to have a grounded (earthed) conductor installed. When this happened the ungrounded Delta system just became a grounded Delta.

?mean that the ungrounded Delta system would now be required to have a grounded (earthed) conductor installed.?

I don?t follow you at all.

What I believe to be true is:
1] To change the wording of the NEC or to start training people that the equipment grounding (bonding) conductor is anything else other than a conductor that connects to earth would mean that ?..
?.. that the equipment bonding operates the OCPD, which is true.

2] To change the wording of the NEC or to start training people that the electrode grounding (earthing) conductor is anything else other than a conductor that connects to earth would mean that ?..
?.. that you?re not quoting me because that?s what I always say about electrode earthing.

We may now be in agreement but I?m not sure because I don?t understand the connection you make in the following statement.

To change the wording of the NEC or to start training people that the equipment grounding (earthing) conductor is anything else other than a conductor that connects to earth would mean that the ungrounded Delta system would now be required to have a grounded (earthed) conductor installed. When this happened the ungrounded Delta system just became a grounded Delta.

David