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O 1997 Portland General Electric. All rights reserved. . ;, APPLICATION _ ,.,. . Electrical Design Commercial Customers Commercial customers located in PGE's core areas may install a building vault where insufficient space is available for pad- or pole-mounted transformers. It is the ~ customer's responsibility to provide space for the utility equipment which will serve .,<.:--. them. Some typical electrical one lines for commercial three-phase service are shown in Figure 1. Note that there is no fusing associated with the transformers in the vault. Protection is provided by internal fusing of the transformers. S~~vitching is generaily done remotely by ei,her s~~vitc~~es or load-brzak elbows. The transformers can either be three-phase pad mounts or single-phase units. Customers with sufficient load at two voltage levels may be served from two transformer banks. Transformers The oil filled transformers shall be located in a room with a three-hour ra;ing. Details for the three-hour transformer rooms are found in the "Structural Requirements and Fire Protection" section of this standard. Primary service into the vault and wiring inside the vault is usually direct burial wire. PGE defines the point of service at the secondary panels. The use of pre-molded connectors allows for all of the primary system to be dead front. The disconnect switch is used as a main building disconnect and shall be remotely operable by the local fire deaartment, in emergency only, with an extension handle through the vault wall. The requirement of the switch is determined by th~ local authority's interpretation of NEC 230-70. The local authority may consider the point of service to be the location where the primary enters the building and require the installation of the disconnect switch. The disconnect switch can be located electrically either ahead of or behind the main fuses. The location would be dependent on physical considerations. Spot Network vaults, typically are not equipped with extension handles on the disconnect switch, which are normally used by the local fire department for emergency only. The primary risers in the building are usually radial in nature; i.e. each riser feeds only one transformer. An alternate scheme would be to loop the riser cables to provide an alternate source to each transformer. This will increase the reliability for each transformer, but will increase the cost to PGE and the customer for more wire and ducts. PGE PROPRIETARY MATERIAL - THIS INFO IS BASED ON ASSUMPTIONS 8 CRfTERIA WHICH MAY NOT BE V?~LID CUTSIDE THE PGE ELECTRIC SYSTEM - FCR INTERNAL USE ONLY UNDERGROUND BUILDING CLASS A X DESIGN CONSTRUCTION VAULTS T&D STANDARDS UNDERGROUND DATE 08-09-96 P.G.E. CO' STANDARD LD-310-07-02 ~kA~~~- Men u - Close -~