NORFNSA Replace Secondary Unit Substations NH-139 NORTH & SOUTH

Priority Order# 2 “SWIB to develop scope and estimate and prepare project for special project consideration”. This project will replace two old Secondary Unit Substations unreliable for operations and beyond any repairs, with new unit substation pairs for NH139 building support. The project replaces 2‐two 34.5kV/208V secondary unit substations, referred to as lineup "North" & "South" servicing the building NH‐139. The replacement will include two existing unit type transformers with oil leaks, an old 600V switchgear beyond any repairs, and necessary duct‐banks with low and medium voltage cable runs. The existing secondary unit substations lineup will be replaced with a new Double‐Ended Secondary Unit Substation, which include new 600V Metal‐Clad Switchgear with redundant backup draw‐out power circuit breakers to critical loads in the building during preventative maintenance, two 1500kVA 34.5kV‐208Y/120V Three‐Phase Standalone Pad‐Mounted Transformers outside of the building, new primary and secondary duct banks, associated medium and low voltage cabling. New cabling will terminate at a new double ended MC‐SWGR with a main and Tie Circuit Breakers, and transitioning connection to the existing switchboards in the electric vault for servicing building NH‐139.