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#81341 - 08/03/02 07:39 AM Grounding Electrode Conductors  
jes  Offline
Member
Joined: Jul 2002
Posts: 103
CT
4 story apartment complex built in 1995. As near as I can determine the entire structure is ONE building. There a six 800A, 120/208Y 'services' fed from utility padmounts and located in DIFFERENT parts of the building (floors and wings). Service conductors are routed to each electrical room through poured concrete encased conduits to an 800A fused switch. This then feeds the meter bank/apartment breaker group.
Now that's all pretty interesting (and I'll assume the AHJ gave the contractor permission to do that) but what I'm really concerned with is the GECs. There is one 4/0 AL run from each disconnect to the common utility space where the water main enters. The main is 4" CU and each GEC is separately clamped to the pipe as it enters. No supplemental electrodes provided. The water piping in the building is plastic after it leaves this room.
Workmanship looks good but does anyone have any comments on that lash-up??


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#81342 - 08/03/02 08:37 AM Re: Grounding Electrode Conductors  
sparky  Offline
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Joined: Oct 2000
Posts: 5,308
jes,
for the sake of good chat, please clarify here......
does the 4" CU H2O main go to plastic after it enters the building?
Or is the external plumbing plastic, and go to CU on entry?
Is this a municipal H2O main?, intergral to other buildings in close proximity ( especially of the X-former) ?
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#81343 - 08/03/02 09:16 AM Re: Grounding Electrode Conductors  
jes  Offline
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Joined: Jul 2002
Posts: 103
CT
Good Morning Sparkster!
OK, the copper line is the municipal supply and is continuous underground as far as I know. The change to plastic occurs on the building side of the GEC connections (about 18" of copper before the changeover)and the building plumbing is for the most part plastic. The padmounts are on the back side of the building - opposite of the street with the watermain. There is also a metal sprinkler riser in the same room that is not bonded (which needs to be) but that doesn't change the basic question about the GEC connections.
There are other buildings across the street but we're talking 75-100 ft or so in all directions. HV to the 2 padmounts comes in from the street underground.

By the way, the 4/0 AL GEC is OK size-wize for the service conductors.



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