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OO 1997 Portiand General Electric. All rights reserved . The vault door shali have a PGE keyway, which accepts the standard PGE station key. If any other locked doors must be passed through to get access to the vault, then the customer should provide lock boxes. Duct Sizing Ducts to be used for installation of electrical conduits should meet the following standards. Primary Raceway Ducts intended for primary conductors should be electrically outside of the building. This is accomplished by following the NEC section 230-6. Conductors shall be considered outside of a building or other structure under any of the following conditions: (1) where installed under not less than 2 inches of concrete beneath a building or other st~ucture; (2) where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 2 inches thick; or (3) where installed in a transformer vault conforming to the NEC requirements. Thin-wall IMC ducts and rigid ducts is not acceptable. Ducts from the property line to the building is supplied by the customer and will be Schedule 40 electrical ducts. All bends in the ducts run should be steel, with 36-inch radii minimum. See Ducts & Road Crossings Design Standard, STD. LD-310-10, "Conduit Sizing Criteria" for determination of duct size. Be sure to increase duct dimensions if runs are over 150 feet and more than one bend. Each duct entering through the vault floor should have a 4- to 6-inch concrete lip poured around it to keep water or oil from entering the duct. For duct runs lon~er than 150 feet, duct diameter is to be increased by 1/2 inch; for ~ three 90 degree bends per run, duct diameter is to be increased an addition 1/2 inch. Consult with the Engineer or Design's supervisor when run exceeds 300 feet in total length or exceeds 270 degrees in bends. See Ducts & Road Crossings Design Standard, STD. LD-310-10, "Jamming Ration Calculations". Secondary Raceway Secondary ducts should be sized according to The Oregon Electric Service Requirements book. (See Table 2 and Table 3) A rule of thumb to follow is to allow one 4-inch duct for each 400 amps of service. It is preferred that 4-inch ducts be used in all cases. Bends in secondary ducts shall be steel or fiberglass and have a minimum radius of 36 inches for duct sizes up to 4". Sheet metal gutter ways can be used for the secondary raceway between a dry-type transformer and the distribution panel. The recommended minimum cross-sectional area for a gutter way is 64 square inches. PGE PROPRIETARY MATERIAL - THIS INFO IS BASED ON ASSUMPTIONS 8 CRITERIA WHICH MAY NOT BE VALID OUTSIOE THE PGE ELECTRIC SYSTEM- FOR INTERNAL USE OP~Y UNDERGROUND BUILDING CLASS A VAU LTS UNDERGROUND P.G.E. CO. STANDARD X I DESIGN I I CONSTRUCTION I T8~D STANDARDS ~ DATE 08-09-96 LD-310-07-09 ~°~E~`~~ -- Menu - Close -