NEC article 230

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alixenos

alixenos

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Location
Florida
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Electrical Design Engineer
Hello,

My senior engineer gave me the task to look at the nec 230 and address the following situation.

We have a fire pump room, and the fire pump has its own service via 45KA step up transformer. I need to move the 45KVA to the outside of the fire pump room and follow the direction of the NEC 230 to address the new modifications.

My question is: where to look exactly in article 230 and what to look for when I want my design to be code compliant.

Sorry but I'm confused and don't know what to do.

Thank you
 
Your supervisor may be giving you an incorrect reference.

What is the source of power to the 45kva transformer ?
 
Understand.... but where does the 208 supply originate ? What protects the transformer primary wiring now ??
 
augie47 said:
Understand.... but where does the 208 supply originate ? What protects the transformer primary wiring now ??
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its coming from the Utility transformer, and service conductors are underground conductors running to the fire room.

He wants to protect the primary side of the transformer with a disconnect but I don't know if that disconnect should be a fused or a non fused one, and what the rating of that disconnect.

Thank you so much for your help.
 
It is a common misapplication to consider all transformer secondary as "services.

So your utility service is 208V feeding this transformer. Is there a service entrance switch or breaker on the 208V feeding this transformer or is it connected directly to the utility?
 
jim dungar said:
It is a common misapplication to consider all transformer secondary as "services.

So your utility service is 208V feeding this transformer. Is there a service entrance switch or breaker on the 208V feeding this transformer or is it connected directly to the utility?
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Its connected directly to the utility.

I want to move this transformer from the inside of a fire pump room to the outside and consider the NEC code. I totally new and not sure how to navigate article 230 to make the new design code compliant.
 
I can't think of a situation where the original install (transformer fed directly form utility) would have been permitted. I would double check to see if there is not some protective device ahead of the transformer.
In your case Art 695 is as important as Art 230. I would start at 695.5
 
augie47 said:
I can't think of a situation where the original install (transformer fed directly form utility) would have been permitted. I would double check to see if there is not some protective device ahead of the transformer.
In your case Art 695 is as important as Art 230. I would start at 695.5
Click to expand...
Thank you, I will.
 
The 208Y primary to 480 delta step up trans former is going to complicate things and a very poor choice in my view. I would question if the fire pump controller is even approved for a delta source either corner grounded or ungrounded.
I would also add that this transformer will need to be in the fire pump room or outside the building.
 
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