ECN Forum Forums Code Related Discussion NEC & other Code issues 2500 KVA 480/277 secondary Transformer conduit & w

I guess I'll learn to not assume things. But you made no mention of whether it was Service or Feeder or Customer owned or Utility. I'll keep my mouth shut from this point forward on your post. And the word is "Parallel"

George
No offense Meant I (ALWAYS) respect your Opinion, and your spelling corrections of my posts. :)) REMEMBER I;m just a Yooper.
Yoopersup

The option to use bus duct assumes that the PoCo hasn't set the transformer. Indeed, I'm assuming that the substructures haven't been constructed. In which case you'd engineer Service to use standard components.

PG&E has cut sheets for laying out bus duct transformers. Not uncommonly, the transformer is situated right next to the building (concrete curtain wall) such as to permit getting from outside to inside with standard elements.

If the PoCo has set it's transformer and you'd need 40 feet of bus duct then expect them to shoot it down. They do not favor extended runs above ground on the secondary side, and the secondaries are deeded to them as a matter of course after acceptance.

At that distance, I'd say copper in Schedule 40 PVC, perhaps some DB120 for the deep horizontal raceway, is your only game. There is no choice.

The PoCo is going to call this tune.

The ownership varies from utility to utility. Here all secondary conductors and raceways except those for one and two family dwelling units are owned and maintained by the customer. The service point is the transformer secondary terminals.

Out here in Southern California, some Utilities own and maintain Service Feeders + Ducts (Secondary Feeders), and a few make the Customer the responsible owner of the Secondary Feeders and Ducts.

With all Utilities, Secondary Ducts are installed by the E.C. (or developer) per the Utilities' "ESR" (Electrical Service Requirements) - verified / specified by the Service Planner involved with that given Project (Planning Engineer of that district).

Most install the Secondary Feeders, however, the "few" other Utilities require the Customer to install the Secondary Feeders - and terminate them at the Service Equipment (typically at Lug Landings in an UGPS).
The Utility terminates the other ends to the Transformer.
These Secondary Feeders + Ducts are declared "Customer-Owned"

For the Utilities that supply + install the Secondary Feeders, only a Pull Rope of specific size and type, is required. Customer ownership may or may not be declared - all depends on the location and design factors.

If Primary Feeders are required (as in a new PMT), all Utilities require the Customer to provide Duct(s) from Vault to Pole (or etc.), with a Pull rope installed.
These also will be installed per ESR + Specifications from Planner.

Primary Feeder Conductors are supplied, installed and termianted by the Utility.
Primary Feeders + Ducts are owned by the Utility.

Additionally, any Transformer Vaults + Pads are supplied + installed by the Customer (per ESR / UGS ((Underground Structures Requirements)) and Planner), and are typically Customer Owned (so if anything breaks, or if it needs to be moved, the Customer is responsible).
The Transformer is owned by the Utility.

Same is applied for PMC and Primary Switch Pads.
Customer supplies and installs, plus is typically responsible owner.
Utility owns the Capacitor Banks and Enclosure, or the Primary Switch and Enclosure.

This is in regards to Commercial and Industrial Customers.

I would imagine Residential Customers are responsible (owner) for anything between the Service Entrance, and the Line side of the Meter,- on Above Ground Service Attachments (Utility responsible for anything attaching to the riser mast).

For Underground Service Attachments: not owners of Service Laterals (Feeders) terminated to the Meter's Line Side lugs.
Most likely Customer supplies Duct to a Pullbox, and the Utility becomes owner of the Duct when Service is supplied.

Just goes to show, there are many different ways for Utilities to do things.

FPN: Always Verify EVERYTHING with the Utility Service Planners!!!

***FYI:***

We are designing a very large Industrial Project, which will have at least Two (2) 4,000 Amp 480Y/277V 3 Phase 4 Wire Services (a third 4,000 Amp Service may be required for the "Phase II" portion of the Project).

The Utility has requested us to specify Bus Duct to be installed for Secondary Service Feeders, between the Transformer(s) and the Service(s).

Transformers will be Pad Mounted 2,500 KVA 5.5% Z units, and will be located apx. 35 feet from the Service Equipment.

Sure the Bus Duct is expensive, but it works out about even, as compared to the Labor + Materials - along with Trenching issues, of Paralleled Feeder Ducts and Feeder Conductors.

Scott35