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Thread: What is service equipment ATS or Main Distribution Panel

  1. #1
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    What is service equipment ATS or Main Distribution Panel

    I have church and has incoming utility as well as emergency generator. Electric utility has two separate feed from the utility transformer to two ATS. One which goes to ATS 1 and another which goes to ATS 2. ATS 1 downstream has main distribution panel. ATS 2 downstream is fire pump. Both ATS 1 and ATS 2 has one same emergency generator on emergency side and electric utility on normal side. The emergency generator is grounded. NEC 250 handbook mostly shows panel as service equipment. Can someone tell me where I need to place system ground, ground bar, neutral bar and what article in NEC 2014 would apply?
    Last edited by codequestion; 10-05-17 at 11:21 AM.

  2. #2
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    Quote Originally Posted by codequestion View Post
    I have another project which is church and has emergency generator. Electric utility is coming on normal side and emergency side is generator on ATS. Downstream of utility and generator is ATS. Downstream of ATS is Main Distribution Panel. NEC 250 handbook mostly shows panel as service equipment. Can someone tell me where I can have system ground, ground bar, neutral bar and what article in NEC 2014 would apply?
    I think you are describing that your service conductors connect to the ATS. In that case you must have a service entrance rated ATS and main boding jumper would be there.
    Be careful of terms here. You say this is an "emergency" system , implying an Article 700 system, but it is running the whole service. This is not code possible. If you have a single, service rated ATS then this will have to be an Article 702 system and as such could not supply any "emergency" loads such as exit or egress lighting.

  3. #3
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    Just added to above that generator is grounded. Both ATS 1 and ATS 2 have to be service rated and have system grounding?

  4. #4
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    Quote Originally Posted by codequestion View Post
    Just added to above that generator is grounded. Both ATS 1 and ATS 2 have to be service rated and have system grounding?
    Whoa! At first I thought I missed these details but then I realized you edited your post while I was responding to your original text. This changes everything.
    For starters, an ATS serving a fire pump must be located in the fire pump room and listed for for fire pump use. This is typically done with a combination fire pump controller/ATS listed as a package and listed as service equipment. Typically, you then bring service conductors directly from the POCO meter to the controller. Is this what you have? Do you have engineered drawings?

  5. #5
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    Attached is the diagram.
    Attached Images Attached Images

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