Transformer between service XFMR and customer meters

tecorp

Member
Location
SoCal
Occupation
Electrical Engineer
Hello,

I am working on a project for a multi story multi family building. There are meter stacks for each individual unit. So current single line shows 208/120V service that is distributed to each meter, which then goes to each load center per unit. The proposed service voltage comes with a ton of voltage drop issues.

I want to propose that we go to a 480/277V service so that these voltage drop issues are solved. However, I am unsure if this will be allowed by SCE since the new single line will become 480/277V service, then a step down transformer (I am guessing this is SCE owned), which is distributed to each meter, which then goes to each load center per unit.

Again, the service is SoCal Edison.

Just wondering if anyone had any input on this. I am looking at SCE's ESR and am not finding anything concrete.

Thanks,
te
 

tecorp

Member
Location
SoCal
Occupation
Electrical Engineer
I would expect the 480 to 208 transformer would be customer owned and on the load side of the service point.
So would you see any issue with this SLD?

Incoming 480/277V (utility owned) ->
Step down transformer (customer owned) ->
Meter stack for each individual unit (not sure who owns this, but I'm sure the owner will not want to deal with the utility. They will want SCE to bill and get payment from each apartment lessee)
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
So would you see any issue with this SLD?

Incoming 480/277V (utility owned) ->
Step down transformer (customer owned) ->
Meter stack for each individual unit (not sure who owns this, but I'm sure the owner will not want to deal with the utility. They will want SCE to bill and get payment from each apartment lessee)
You can do a 480V service -> 480V CT meter -> 480V service disconnect -> customer MDP -> feeders -> customer owned transformers -> customer owned sub meters.
And if your doing that its better to bring the 480V feeder up the floors and do single phase 120/240 transformers for a floor or group of floors.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
The proposed service voltage comes with a ton of voltage drop issues.
How does changing the service voltage to 480V change the voltage drop issue when your distribution, to each unit is 208Y/120?

The power company will only provide you one voltage. Your client would be responsible for the losses and voltage drop across the 480:208Y/120V transformer. And don't forget the issue of providing the metering for each unit.
 

tecorp

Member
Location
SoCal
Occupation
Electrical Engineer
How does changing the service voltage to 480V change the voltage drop issue when your distribution, to each unit is 208Y/120?

The power company will only provide you one voltage. Your client would be responsible for the losses and voltage drop across the 480:208Y/120V transformer. And don't forget the issue of providing the metering for each unit.
we'd be distributing 480v across campus up to a step down xfmr right next to the individual meters instead of distributing 208v across campus to the individual meters
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
we'd be distributing 480v across campus up to a step down xfmr right next to the individual meters instead of distributing 208v across campus to the individual meters
I think you need 208 volt services at each of the campus locations where there will be meters.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
we'd be distributing 480v across campus up to a step down xfmr right next to the individual meters instead of distributing 208v across campus to the individual meters
You want to install a customer owned transformer on the Line side of the meter?? That's not gonna fly.
 
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