2 Different Transformers with different ratings

Location
NJ
This is a semi-big banquet hall and it's at least 1000ft from the main road.
But near the main road on the property, I see one 480Y/277V Transformer at 225kVA at 3P.
Than near the banquet hall, I see another one at 208Y/120V Transformer at 500kVA.

But inside the Electrical room, I see the main MDP rated at 1000 AMP. I do not see another Electrical room and there was only 1 meter as well.

Is there any way I can increase the service to the building at 120/208V, 3P.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Probably a second electrical room hidden somewhere, probably in the kitchen area, as most kitchen equipment is 120/208. Buildings are allowed to have more than one service if it is for different voltages or power type. Should be a plaque stating where the other service is though.
 
Location
NJ
I though so too, but I walked around the entire building with the maintenance guy and he said there was only one electrical room.
Than the maintenance guy found the Electrical drawings and it confirmed that there was only 1 Electrical service as well.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector
I'm afraid I don't understand. Is your concern the transformers size or exceeding the 1000 amp panel size ?
 
Location
NJ
Since I get how the 208V works, since 500KVA/sqrt(3)*208 = 1,388.89 A.
So the 208V transformer is feeding the Main Distribution Panel in the electrical room.

I was wondering how the 480V transfer is feeding the 208V transfer?
Since I need to get an additional 400 AMP for the new expansion project
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector
Is it not possible the 480 transformer is feeding some other structure than your building ???
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Is the 500 kva transformer utility owned? Does the MDP have a GEC run to it and contain the MBJ?
 
Location
NJ
Is the 500 kva transformer utility owned? Does the MDP have a GEC run to it and contain the MBJ?
There was only one meter near the 500 kVA (480V) transformer with a CT and disconnect.

I also did not open the MDP to check for these items


Is it not possible the 480 transformer is feeding some other structure than your building ???
There is only 1 Big building on the lot of land.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Since I get how the 208V works, since 500KVA/sqrt(3)*208 = 1,388.89 A.
So the 208V transformer is feeding the Main Distribution Panel in the electrical room.

I was wondering how the 480V transfer is feeding the 208V transfer?
Since I need to get an additional 400 AMP for the new expansion project
Poco never oversizes the transformer, so the 1000 amp main is most likely 480.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
I was at a store in Chattanooga TN a couple of years back, nameplate rating and breakers were 120/208, but someone converted it to 277/480, and it was live! Don’t know how they got the poco to hook it up, as when the new tenants moved in, the inspector caught it, so it must not have been permitted. There was another service in the room that was actually 120/208, and came off the second transformer sitting on the same pad!
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Is this in a state or area where utilities are deregulated? The transformers may be owned by the customer, which might explain the over sizing. The other transformer may not even be connected, and was installed as “future”
 
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