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#827 - 03/21/01 08:45 PM Service and GEC  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
A 600 amp OH service...2-3" rigid conduits with 3-350 kcmil enter a C/T cabinet(exterior) leave the C/T cabinet and go to an MDP(immediate interior) with a main fused switch.

Now take the exact same arrangement, place it next to the first service, it is fed from one drop. One Service?

If it is one service, then what is the arrangement and size of the GEC, Main bonding jumper, and equipment bonding jumpers on the supply side of the service?

Do I size the MBJ in each MDP based on the sum of equiv. area of 4 sets of 350's or just the 2 sets that enter each MDP?

Same question as the paragraph above but replace MBJ with EBJ?


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#828 - 03/22/01 07:52 AM Re: Service and GEC  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
ok, let me start your thread off one step at a time and let others chime in,

230-2 ( number of services), if this where an underground entry ,then it would all be considered ONE service. But it is OH, therefore considered TWO

[This message has been edited by sparky (edited 03-22-2001).]


#829 - 03/22/01 01:52 PM Re: Service and GEC  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
Could I get a little elaboration on why? Code sections would be a big help. I really don't see anything that says it is two services, except maybe for the fact the disconnects would not be interpreted as located together.


#830 - 03/22/01 07:22 PM Re: Service and GEC  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Steve;


230-2 Number of Services.
A building or other structure served shall be supplied by only one service unless permitted in (a) though (d).

For the purpose of section 230-40 Ex #2 only, underground sets of conductors , size 1/0 and larger, running to the same location and connected together at their supply end, but not connected together at their load end, shall be considered to be supplying one service.

as i see it, you need to define 1 or 2 services before you can really start on your other Q's.

why does the code make OH & UG a difference here, i'm sorry i can't say.

[Linked Image]


#831 - 03/23/01 11:15 AM Re: Service and GEC  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
If you have the handbook, figure 230.2D shows the situation (kinda) I am talking about with an overhead drop and calls it one service.

I know that by 230-2 specifically saying that underground 1/0 and larger connected at the supply but not at the load is considered one service, it is implied that OH 1/0 or larger would not be considered one service, but the Code does not explicitly say that it is not.

Thanks for the replies sparky. It seems I'm not getting a lot of replies on this and other BB's is my question unclear? If so, just follow the idea of service entrance conductors being connected on the supply side but not the load side. I need to approve or not approve a set of prints very soon and I really appreciate everyone's input into these strange situations even if it is just an opinion with no real code to back it up.


#832 - 03/23/01 04:43 PM Re: Service and GEC  
sparky  Offline
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Joined: Oct 2000
Posts: 5,311
I only have the 96' handbook, this code has changed, the rationale escapes me, i see replies to your Q in other boards,same thing.

If you are the party who's approval this plan will bear, would'nt you consider the worst case senario?

I say this in light of your grounding concerns, which would not constitute a high dollar difference if it were considered 1 service....

just an observation

[Linked Image]


#833 - 03/23/01 05:07 PM Re: Service and GEC  
Mike  Offline
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Joined: Feb 2001
Posts: 62
Installing a second CT metering equipment separate from the existing one would mean two services to me.


#834 - 03/23/01 05:12 PM Re: Service and GEC  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
Mike,

Metering of power can be done in many ways and one meter or 50 meters it could still be one service. Apartment building, strip mall, etc. could be one service with many meters.


#835 - 03/23/01 06:15 PM Re: Service and GEC  
Mike  Offline
Member
Joined: Feb 2001
Posts: 62
Steve,

Your examples are multi-occupancy buildings.
Which is NEC acceptable. Washington state's electrical law states, "a service drop terminates in the utility's meter equipment." Look in the NEC book for the definition of service. I consider the reference to equipment in the definiton to include the metering equipment. I guess the best thing for you to do is ask your local AHJ.


#836 - 03/23/01 06:44 PM Re: Service and GEC  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
Mike,

Thanks for the replies. You're right, my first example is one occupancy and the later examples are multi occupancies. Are you saying the same arrangement of service would be considered one service if it is multi occupancy, and two services if it is single occupancy?

And yes there will be a difference between Wahington state and here as the service drop ends here at the point of attachment to the building, so we may be comparing apples and oranges based on different definitions.

Last, I am the AHJ trying to make sure I look at this properly and approve or not approve the plans based on NEC intent. I think I will approve it with the info I've got, (thanks everyone), but I still am not sure if it is one service or two.


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