EGC used as GEC?

[neonbkw]

Greetings, I am an EC building a service for an old school building converted to office use. The layout of the equipment leads me to ponder whether I can use the EGC of a 200A feeder as the GEC from the water pipe ground back to the service disconnect, if I size accordingly.

Based on the service entrance conductors, the GEC needs to be 2/0 copper. What I'd like to do is terminate this 2/0 GEC on the ground bar of a 200A MLO loadcenter located in close proximity to the water line, and upsize the EGC back to the main service disconnect where the N/G bond is located. The supplemental ground rod will be connected at this main disconnect.

So far this sounds ok in my mind, but there is more. Along side the previously mentioned main service disconnect, there is another just like it with a feeder going to a different part of the building, and along side that there is a loadcenter with a 200A main breaker acting as a service disconnect for a total of three service disconnects grouped in one area. This is where my brain starts to smoke when it comes to making sure I have the grounding electrode system down pat. I know I could just run the 2/0 all the way back to the service disconnects and make taps to each one, but I'd really like to utilize my original plan to save on time and material. Who isn't trying to save anything they can these days?

Please let me know what you think, as I'm always happy to learn something new.

Please let me know how this sounds, as this is something I have never encountered thus far. Thank you.

 

[radiopet]

250.24 Grounding Service-Supplied Alternating-Current
Systems.

(A) System Grounding Connections. A premises wiring
system supplied by a grounded ac service shall have a
grounding electrode conductor connected to the grounded
service conductor, at each service, in accordance with
250.24(A)(1) through (A)(5).

(1) General. The grounding electrode conductor connection
shall be made at any accessible point from the load end
of the service drop or service lateral to and including the
terminal or bus to which the grounded service conductor is
connected at the service disconnecting means.

 

[Smart $]

I and at least one other major contributor to this forum agree it is okay to have a dual purpose GEC/EGC, provided all the requirements of both are met.

Having said that, I hear there is a (are) proposal(s) for the 2011 edition to end this practice...

 

[radiopet]

I don't guess I am a major contributor but then again I don't agree. We have defined terms GEC and EGC's and specfic requirements for each. But then again my opinions are only mine...lol

 

[neonbkw]

Thanks for the input guys. I'm still going to run this by the AHJ just incase. Better to be safe then have to change something later.

 

[LarryFine]

I don't guess I am a major contributor but then again I don't agree. We have defined terms GEC and EGC's and specfic requirements for each. But then again my opinions are only mine...lol

Paul, are you saying that it can't physically be done, or just that you wouldn't accept a single conductor?

 

[radiopet]

I am saying that while anything can physically be done, I don't believe as it is specifed that it meets the intent of the NEC. I believe that when the NEC deals specifically with conductor types in reference to GEC and EGC it's intent is they are what they are and the point of connection is specific in those cases.

However, everyone is clearly open to disagree...this is my opinion only.

 

[iwire]

I see it more like radiopet.

That said if you where to use the EGC as the GEC it seem it would be hard to comply with the 'continuous' requirements.

 

[dcspector]

I see it more like radiopet.

That said if you where to use the EGC as the GEC it seem it would be hard to comply with the 'continuous' requirements.

Same here. What I am reading from the OP I see a 250.64(C) and agree with Paul as well, what is defined as a GEC and a EGC. Just my pennies worth.

 

[Smart $]

I believe that when the NEC deals specifically with conductor types in reference to GEC and EGC it's intent is they are what they are and the point of connection is specific in those cases.

The big question when you start talking "intent" on this matter is are you talking intent for specifying an EGC as an EGC, and a GEC as a GEC, or are you talking intent as to whether the purposes of these grounding conductors can be met with one conductor? While neither perspective is mutually exclusive of the other, it seems to me that people take an opinionated stance as though they are.

 

[Smart $]

As a side note, section 250.54 Auxiliary Grounding Electrodes seems to support the concept that an EGC can serve a dual purpose as a GEC.

 

[iwire]

I have been seeing your argument until this ...

As a side note, section 250.54 Auxiliary Grounding Electrodes seems to support the concept that an EGC can serve a dual purpose as a GEC.

..... I don't see that at all.

But I do think that 250.30(A)(4) suggests the GEC must be separate.


In the end it must not be clear if they are going to change the rules for 2011.

 

[dcspector]

I have been seeing your argument until this ...



..... I don't see that at all.

But I do think that 250.30(A)(4) suggests the GEC must be separate.


In the end it must not be clear if they are going to change the rules for 2011.

The OP is talking about an SDS?.....Grounding Multiple SDS systems 250.30(A)(4) would be lets say SDS transformers per floor and utilizing a main GEC. From the OP I still see a 250.64(C) violation. If I read the OP correctly.

 

[Smart $]

I have been seeing your argument until this ...
..... I don't see that at all.

Thought it was rather obvious... but apparently not

250.54 Auxiliary Grounding Electrodes. One or more
grounding electrodes shall be permitted to be connected to
the equipment grounding conductors specified in 250.118
and shall not be required to comply with the electrode
bonding requirements of 250.50 or 250.53(C) or the resistance
requirements of 250.56, but the earth shall not be
used as an effective ground-fault current path as specified
in 250.4(A)(5) and 250.4(B)(4).

IMO, any conductor connected to a grounding electrode is a grounding electrode conductor!!!

But I do think that 250.30(A)(4) suggests the GEC must be separate.

This one is back at you, as I don't see any relevence whatsoever...

250.30(A)(4) Grounding Electrode Conductor, Multiple Separately Derived Systems. Where more than one separately derived system is installed, it shall be permissible to connect a tap from each separately derived system to a common grounding electrode conductor. Each tap conductor shall connect the grounded conductor of the separately derived system to the common grounding electrode conductor. The grounding electrode conductors and taps shall comply with 250.30(A)(4)(a) through 250.30(A)(4)(c). This connection shall be made at the same point on the separately derived system where the system bonding jumper as installed.

 

[Smart $]

The OP is talking about an SDS?.....Grounding Multiple SDS systems 250.30(A)(4) would be lets say SDS transformers per floor and utilizing a main GEC. From the OP I still see a 250.64(C) violation. If I read the OP correctly.

OP is regarding a service and a subpanel, no SDS.

As for a 250.64(C) violation: What if the conductor passes through the subpanel without splice and terminates at the electrode, and the panel is grounded by way of a non-splitting or irreversible tap of the said conductor?

 

[dcspector]

OP is regarding a service and a subpanel, no SDS.

As for a 250.64(C) violation: What if the conductor passes through the subpanel without splice and terminates at the electrode, and the panel is grounded by way of a non-splitting or irreversible tap of the said conductor?

The op mentioned the GEC went to panel busbar. Also my previous post was questioning Bob on the section # 250.30(A)(4)

 

[dcspector]

OP is regarding a service and a subpanel, no SDS.

As for a 250.64(C) violation: What if the conductor passes through the subpanel without splice and terminates at the electrode, and the panel is grounded by way of a non-splitting or irreversible tap of the said conductor?

On another note. Is this a test? I am simply trying to answer the OP not what ifs. Your what if is fine. But that was not what the OP mentioned.

 

[Smart $]

The op mentioned the GEC went to panel busbar. Also my previous post was questioning Bob on the section # 250.30(A)(4)

I was clarifying the OP scenario was not an SDS installation.

On another note. Is this a test? I am simply trying to answer the OP not what ifs. Your what if is fine. But that was not what the OP mentioned.

So it is OK for you to speculate on other's posts, but I cannot speculate on yours. Is that what you are trying to say? :roll:

 

[don_resqcapt19]

I think the code is totally wrong about the need for a GEC for a transformer that is located within the same building as the service disconnect. There is no technical reason to require anything more than the primary EGC between the main service an a transformer. The EGC that is sized based on T250.122 can safely do both jobs and there is no reason to waste additional copper by installing both an EGC and a GEC for this type of application.

It is my opinion that in some rare cases you could install a single conductor that would serve as both the EGC and the GEC under the current code rules.

 

[Smart $]

I think the code is totally wrong about the need for a GEC for a transformer that is located within the same building as the service disconnect. There is no technical reason to require anything more than the primary EGC between the main service an a transformer. The EGC that is sized based on T250.122 can safely do both jobs and there is no reason to waste additional copper by installing both an EGC and a GEC for this type of application.

It is my opinion that in some rare cases you could install a single conductor that would serve as both the EGC and the GEC under the current code rules.

Along with that, I think most if not all non-believers are so rapt up in trying to follow [or make] the letter of the "code", they forget about the elemental physics of the application and purpose.