Question Regarding Number of Services & Grouped Disconnects

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Sunny_92

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York, PA
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Electrical Engineer
Hoping someone can help me understand the NEC requirements regarding number of services and grouping service disconnects, as they apply to the following situation. Location is PA so 2008 NEC is applicable. Here's what's being proposed:

There is a building that we are looking to build a new service to. The building will be supplied by an outdoor pad-mounted transformer that will be owned by the customer, and fed from a customer-owned MV feeder. What's being proposed is pulling four sets of #350 CU conductors from the transformer to the building, and landing two sets on one 600A fused disconnect, and landing the other two sets on another. The existing single phase service panel will be re-fed from a circuit off a new busduct.

My question/confusion comes from the fact that two sets of conductors are going to one disconnect and two sets are going to another. Does this technically count as two services? Is this allowed?

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The feeder and number of building disconnects are fine. Where is the system bonding jumper installed? If there is not one at the transformer and at the building disconnects (permitted by 250.30(A)(1) Ex #2) you will need a supply side bonding jumpers in the raceways.
 
don_resqcapt19 said:
The feeder and number of building disconnects are fine. Where is the system bonding jumper installed? If there is not one at the transformer and at the building disconnects (permitted by 250.30(A)(1) Ex #2) you will need a supply side bonding jumpers in the raceways.
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Thanks for the response! I appreciate the advice on the grounding as well, although I am already aware of what you stated. We'll likely go with a bonding jumper at the transformer and at the disconnects, and forgo the supply side bonding jumper.
 
Sunny_92 said:
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My question/confusion comes from the fact that two sets of conductors are going to one disconnect and two sets are going to another. Does this technically count as two services? Is this allowed?
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Technically they are not services. They are a building supplied by two sets of transformer secondary conductors (feeders). This would be in violation of 225.30. You will have to make all 4 sets parallel to the building, then you can distribute to 2 disconnects.
 
Smart $ said:
Technically they are not services. They are a building supplied by two sets of transformer secondary conductors (feeders). This would be in violation of 225.30. You will have to make all 4 sets parallel to the building, then you can distribute to 2 disconnects.
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This was my suspicion. So to be code compliant, we would need to pull all four sets into a trough, terminate them onto a terminal block for each phase, then feed each disconnect from those terminal blocks. Is that correct? Of course I'm sure there are other ways of doing it, but I'm looking for the most economical.
 
Sunny_92 said:
This was my suspicion. So to be code compliant, we would need to pull all four sets into a trough, terminate them onto a terminal block for each phase, then feed each disconnect from those terminal blocks. Is that correct? Of course I'm sure there are other ways of doing it, but I'm looking for the most economical.
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Yes. As you state, one way to do it.
 
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