Single phase transformer with parallel run!

[ftex]

I have not much knowledge about apartment buildings/commercial yet ,and how electrical connections and power is distributed.
like in normal overhead residential,from transformer we can run multi Buses , and from each bus we can connect to multi service cables, base on the load.
But is it same in apartment building?
i think in buildings, only a single bus of transformer goes to main panel, than from panel to sub panels?! (single phase transformer)...

I have seen parallel run on 3phase transformer to service, but is it possible on single phase transformer to have parallel run or it is not necessary?

 

[Ingenieur]

If what you are asking can an apt bldg with multiple units have a one single phase service
yes, common

 

[iwire]

I have seen parallel run on 3phase transformer to service, but is it possible on single phase transformer to have parallel run or it is not necessary?

Your question is unclear but if you are asking if yon can use parallel conductors on single phase systems the answer is yes.

Is it necessary to do so? It depends on the load and the job.

 

[jim dungar]

I have seen parallel run on 3phase transformer to service, but is it possible on single phase transformer to have parallel run or it is not necessary?

It sounds like you are asking if it is okay for one transformer to feed multiple loads, like is commonly done with residential services.
These multiple panels are not paralleled, because the feeds are joined together only on one end.

Yes, transformers regularly feed multiple loads even in industrial installations.

 

[ftex]

Overhead system

Overhead system

I clearly understand residential system, A single transformer can supply multi customers .As you see in picture A.
500kcmil Bus is connect to 7 customers/ 100amp services (maybe different in reality, just made these numbers)
then another Bus is feeding 7 customers with individual services cables.

But in apartment Buildings, I have seen a single Bus is connected to service cable and feeding into a building with much more customers, (like 20 customers (with 20 individual METERS) ...

sorry if i made it hard to understand, i will use some voltage drop example on my next post. to be more clear.
my issue is voltage drop on apt/commercial with multi meters.

 

[Iron_Ben]

But is it same in apartment building?

I have seen parallel run on 3phase transformer to service, but is it possible on single phase transformer to have parallel run or it is not necessary?

Well, we did it when the load on the apartment building warranted it. Example: 25 unit apartment complex. The units were quite small, maybe 600 square feet. There was gas service. The mains at each meter were either 100 or 125 amps, can't recall. The main beaker in the 25 meter gang assembly was a 1000 amp. We fed it underground with two runs of 350 MCM aluminum triplex. The max load it ever drew was around 350 - 375 amps.

What you are bringing up here is on the line side of the meter(s), and so it's the power company's call. And they are not, generally speaking, under the purview of the NEC.

 

[kwired]

I clearly understand residential system, A single transformer can supply multi customers .As you see in picture A.
500kcmil Bus is connect to 7 customers/ 100amp services (maybe different in reality, just made these numbers)
then another Bus is feeding 7 customers with individual services cables.

But in apartment Buildings, I have seen a single Bus is connected to service cable and feeding into a building with much more customers, (like 20 customers (with 20 individual METERS) ...

sorry if i made it hard to understand, i will use some voltage drop example on my next post. to be more clear.
my issue is voltage drop on apt/commercial with multi meters.

Multiple customers on a single source is not limited to residential customers, but is fairly common for small to moderate sized dwellings that are in fairly close proximity to one another. Same often applies to the old "main street" businesses that are all right next to one another, why install a separate transformer for each when it is more economical and/or convenient to supply them both from one even if it needs to be increased some in capacity? If each subscribes to different voltage, number of phases, etc. then there may not be much choice though.

But the superstores are a different issue - they have huge parking lots and other things between them that generally place them far enough apart that it is more practical to serve each one from separate transformers located closer to each facility then to try to centralize a source for each customer.