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#84838 - 05/09/03 08:25 PM GEC connections  
njsparky  Offline
Junior Member
Joined: May 2003
Posts: 3
I'm doing an install to a mixed use office/house as follows. 240volt 3 wire single phase service, 400MCM copper service drop into dual meter pan. Each meters load side is 4/0 awg aluminum SE wire into two seperate 200 amp load centers in the basement. I know that I should be using 1/0 awg copper for the GEC based on tbl 250.66(400MCM), and I know that I should be using #4 solid for the grounded conductor bonding in each load center to the GEC. My question is where should I make that connection. I have had trouble in the past with making connections in the meter pan because it will be inaccessable after the electric utility locks the enclosure. My only thought on this subject is that perhaps the utility will only lock the meter enclosure sections of the dual meter pan. If that is the case, then the center, supply side connection in the meter pan will always be accessable and my problem is solved. The supply side of the meter pan is the only location where the grounded 400 mcm conductor is available. The final question is whether or not I can use a single 4awg run from the 1st loadcenter into the 2nd loadcenter and then out to the point of attachment to the 1/0 GEC


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#84839 - 05/10/03 01:54 AM Re: GEC connections  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Take the 1/0 from the water pipe grounding electode to one of the services and run a #4 from the other service to some point on the 1/0.
Don


Don(resqcapt19)

#84840 - 05/11/03 12:22 PM Re: GEC connections  
njsparky  Offline
Junior Member
Joined: May 2003
Posts: 3
resqcapt19,

thanks for the reply. my only question stems from a diagram in the 2002 handbook(exhibit 250.12 on page 185) detailing the bonding jumper sizing for incoming service raceways and loadcenters connected. With regard to the install described above, the only connection from the meter pan to the loadcenters are the 4-4-2al SE wires feeding from the load side of the meter. I am thinking that I'll probably have to mount a grounding plate in the basement and then run 1/0 into the meterpan from the plate and then to the water pipe and on to the the driven rods. Then I'll probably be fine with 4awg from the loadcenters to the plate.
Any thoughts from anyone would be great.

I love this place, I have been reading for over a year and finally registered. Im glad I did. ( i use to frequent the other site, and i'm not knocking it, but it has gone too commercial for me)


#84841 - 05/12/03 10:58 AM Re: GEC connections  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
The grounded conductor (neutral) can be used for all required bonding and grounding on the line side of the service disconnect(s).
Don

[This message has been edited by resqcapt19 (edited 05-14-2003).]


Don(resqcapt19)

#84842 - 05/12/03 09:36 PM Re: GEC connections  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
Don,

Thanks for clarifying that. What seems to be a misunderstanding among many electricians and inspectors is that the grounding and bonding conductors cannot be set up parallel to the grounded conductor.

I have many electricians in my jurisdiction say that's the way another inspector (from another town) told me I have to do it. I tell them that it is not compliant to install grounding/bonding conductors in parallel with the neutral, but the neutral can be a bond or ground conductor ahead of the service.

Do you consider a metal conduit between two enclosures that are bonded to the neutral a code violation?


#84843 - 05/12/03 10:29 PM Re: GEC connections  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Steve,
Quote
Do you consider a metal conduit between two enclosures that are bonded to the neutral a code violation?

No. Yes, it does create a parallel path, but it is not a code violation. There are a number of parallel paths that can exist on a code compliant installation and they all will carry some part of the grounded conductor current. The one that will carry the most is metal under ground metallic water pipe that is common to a number of houses. The required use of the water pipe as a grounding electrode at each house places the water pipe in parallel with the grounded conductor. This also happens with the bonding of the protector for the TV cable and under ground phone line (if if has a metal gopher jacket).


Don(resqcapt19)

#84844 - 05/13/03 07:49 AM Re: GEC connections  
Gwz  Offline
Member
Joined: Apr 2002
Posts: 197
Don,

By chance, did you leave out a few words on your 05-12-2003 10:58AM post, such as " under certain conditions" ?


#84845 - 05/13/03 10:56 AM Re: GEC connections  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
gwz,
No. See 250.142.
Don


Don(resqcapt19)

#84846 - 05/13/03 08:00 PM Re: GEC connections  
Gwz  Offline
Member
Joined: Apr 2002
Posts: 197
Don,

From the original post, I do not interpret the disconnect(s) of the 200A panelboards (load centers ) in the basement as being on the load side of the Service Disconnect.

I do not see the exceptions of 250.142(B) applying to the installation.

The 250.142 in-part states " - - -, a grounded circuit conductor shall not be used for grounding non-current carrying metal parts of equipment on the load side of the service disconnecting means - - -."

Somehow I read your comment to be: "The grounded conductor (neutral) can be used for all required bonding and grounding on the load side of the service disconnect(s)."

In general, once the grounded conductor (neutral) leaves the service disconnect enclosure, the grounded conductor is not to be re-grounded or used as an equipment grounding conductor EGC.
250.142(B) exceptions and 250.32(B).

Maybe I'm missing the meaning of your statement.


#84847 - 05/13/03 11:46 PM Re: GEC connections  
WebSparky  Offline
Member
Joined: Feb 2003
Posts: 138
Cleveland, Ohio
Hi Don,

Quote
The grounded conductor (neutral) can be used for all required bonding and grounding on the load side of the service disconnect(s).
Don


I guess I'm confused also........

Quote
NEC 2002 250.142 Use of Grounded Circuit Conductor for Grounding Equipment.
(B) Load-Side Equipment. Except as permitted in 250.30(A)(1) and 250.32(B), a grounded circuit conductor shall not be used for grounding non-current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means.


Am I missing something?

Thanks,
Dave


Dave

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