Code problems with this installation? OCP sizing issues.

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Aleman

Senior Member
Location
Southern Ca, USA
Found an oddball power installation and am not sure of the code legalities. I have a 400A breaker from the main (2000A) feeding a 480Y panel protected by a 600A breaker. Conduit and cables are sized correctly for the 400. The 600A panel has a 400A breaker feeding a transformer that supplies a 208Y panel protected by a 800A breaker. All cables are sized for the upstream protection. Best we can determine is that the intent was to upgrade the feed to the 480 panel at some point. Seems screwy to me but not sure if there is an actual violation. As is, the power demand will not exceed the 400A supplied from the main. The loads are primarily HVAC and lighting. Any thoughts on this?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
This is done all the time. There is nothing wrong with the install. Suppose that was a main lug panel...You wouldn't give it a thought as the panel is protected with the 400 amp breaker and conductors to match.
 

Aleman

Senior Member
Location
Southern Ca, USA
Thanks Dennis. I usually work on the controls side of things and am not often involved with larger power installations. The way you put it, you are right. I wouldn't
think anything was wrong if this was out of a lug panel.
 

kwired

Electron manager
Location
NE Nebraska
You could run a 15 amp feeder to a 2000 amp switchboard if you wanted. Kind of have to presume the load is no more then the 15 amp feeder can deliver. Probably a big waste of $$$ but complies or can comply with NEC.

By "can comply" I mostly mean you likely need to add methods of landing a 15 amp conductor in lugs that likely weren't designed for that small of a conductor.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
If the conductors are sized correctly the installation is fine as is. I'm guessing that the 400 amp feeder feeding the 600 amp panel is what's throwing you off.
 
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