4000 amp main for a switchboard being feed as a FEEDER

[Jason Ward]

I have a 4000amp disconnecting means (Breaker) located outside a 6 story multi-family building.
I am feeding a 4000amp 480/277v switchboard located 100' inside of the building. This is considered a "feeder".
Can it be a MLO switchboard or will it require a main?
Thanks for your time and response.
Jason Ward, P.E.

 

[augie47]

I believe the devil will be in the details. "Outside" being the operative word.
If the main is on the outside of the building and attached to the building (therefore 'a part of') then I see no problem.
If the main is not structurally a part of the building then, by Code definition, it can be viewed as a
structure" and Art 225 comes in to play.
The details may makw the installation an AHJ call as to his view of the ,main being a separate "structure"

 

[Strathead]

I believe the devil will be in the details. "Outside" being the operative word.
If the main is on the outside of the building and attached to the building (therefore 'a part of') then I see no problem.
If the main is not structurally a part of the building then, by Code definition, it can be viewed as a
structure" and Art 225 comes in to play.
The details may makw the installation an AHJ call as to his view of the ,main being a separate "structure"

And... as an electrician, I think, "please don't" I know that lock outs are required, but it is much more comforting to have physical control of the disconnecting means when I am working on a piece of gear.

 

[malachi constant]

I believe the devil will be in the details. "Outside" being the operative word.
If the main is on the outside of the building and attached to the building (therefore 'a part of') then I see no problem.
If the main is not structurally a part of the building then, by Code definition, it can be viewed as a
structure" and Art 225 comes in to play.
The details may makw the installation an AHJ call as to his view of the ,main being a separate "structure"

I have put service disconnects outside adjacent to the utility transformer, not attached to the building. Never thought twice about it, never got flagged. I do this rarely but when it is on the table I always make sure the Owner is 100% on board with it. I had never thought of this as being in a gray area but augie makes a good point. I guess it makes sense to run it by the AHJ too.

 

[Jason Ward]

4000 amp main

4000 amp main

Thanks. That is how i saw it. The outside disconnect is with-in arms distance from the building/structure.
I just have an overworked AHJ.

 

[augie47]

Sounds like with a couple of pieces of angle-iron it could be part of the structure

 

[Jason Ward]

I meet with the AHJ Monday morning.
I will let you know how it goes.
Thanks again for your time