service disconnecting means

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TAL

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Gillette, wyoming
I am currently planning for a job that entails installing a SERVICE DISCONNECTING MEANS,(Art. 230.70) I have read thru the code and it defines the location of the disconnecting means, the service entrance conductors, service equipment and service point which I believe I understand. And as I understand the LOCATION of the disconnecting means can be either outside or inside nearest the point of entrance of the service conductors.
But, I need help.
What I have is an industrial plant that has a premises transformer ( pad mount about 250' away, but visible. step-down from 24900vac to 480vac, 3phase) with capability of 2000 amps and service entrance conductors (I am calling them this for now) that come from the transformer and enter the building and terminate into an existing 2000 amp service disconnecting means, there is also a pole that is premises wiring that is carrying 24900vac to the premises transformer and is the owners premises wiring (The owner has told me the serving utility has given designation of this and the service point)
Here's my question, Do I have to have a disconnecting means between that transformer and the existing service disconnecting means that's just inside the building?

I say no, but is the transformer "service equipment"? Which says there will be OCPD there. The code does state that a transformer will have a disconnecting means within sight but I don't know if that really applies here. (Art.450.14) This transformer is making it hard to decipher as its not the utility's, but is premises.
The pole is visible and I thought to put an air switch on it and that would be the primary shut off to the transformer. Well, if you can help me, I sure would appreciate it.
 
If I'm interpreting your post correctly, the service point is on the supply side of the transformer. This would mean your service disconnecting means must be at or after the service point and prior to the transformer primary terminals.

On the secondary side of the transformer, see 240.21(C) as a starting point.


Welcome to the forum! :thumbsup:
 
This makes your building "feeder supplied" and not "service supplied".

So art 230 applies to the service disconnect but art 225 applies to the feeder to the building.

Also would mean that separate equipment grounding and grounded supply conductors would be required if it is a feeder instead of service conductors supplying the building.
 
kwired said:
...Also would mean that separate equipment grounding and grounded supply conductors would be required if it is a feeder instead of service conductors supplying the building.
Click to expand...
Not necessarily... in this case. May depend on NEC edition in force, but under 2014, see 250.30(A)(1) Exception No. 2 and 250.30(A)(2) Exception. Essentially the secondary, feeder, and disconnecting means would be wired the same as a service.
 
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