aout. JOHNSTON ATOLL SUPPORT F &S NO. 0304H TITLE Substations, 4160 Volt Distribution System USER STRUCTURE. FACILITY NO. TG 8.6 SCIENTIFIC STATION NO. Listed Below None per FOD FUNDING ($000) ENGR PROC CONST TOTAL FURN PRIOR YEARS ENGINEERING The typical substation constructed since 1964 is shown on H&N Drawings 91-080-SE1. The typical substation built between 1951 and 1964 is shown on the Law and Wilson drawing made for the Corps of Engineers, Honolulu area, Drawings: and identified as Drawing No. Johnston 71-03-02. 91-080-E]1 thru E41 91-080-E51 thru E53 91-080-S1 thru S6 91-080-SE1 F 91-080-E53 CONSTRUCTION JS 91-027-A100 thru A103 JS 91-027-E100 JS 91-080-E105 thru E108 25-28-01 Sheets 70 thru 74, District File No. 105-10-1 The outgoing 4160 volt, 3 phase, 3 wire circuits. thirteen in number, serve Johnston Island, Akau (North) Island, Hikina (East) Island and Sand Island loads through a distribution system of eleven feeders. Two outgoing circuits terminate at transformers outside of the power plant. These transformers serve the various power plant auxiliary equipment and the power plant utility loads. The existing electrical distribution system on Johnston Island is a modified Loop Radial configuration. This system has been operational for approximately three years. Flexibility is afforded the existing distribution system by the oresence of eleven manually operated, oil-immersed, sectionalizing switches, rated at 400 amperes. The distribution voltage is 4160 volt, 3 phase, 3 wire with 500-mcm conductors; one per phase. The distribution system feeder conductors are routed to their substations through a network of underground concrete-encased duct banks. The sectionalizing switches are located in fenced enclosures. Two of the feeders, Numbers 9 and 10, have a loop con- figuration through Submarine cables, and presently energize the Akau and Hikina Island loads. The feeder routing to Hikina Island is directed through a manhole on Sand Island (U. S. Coast Guard). The Sand Island load has recently been connected to the Johnston Island distribution system. Feeder No. Il is utilized to feed the LOX Plant 900 HP compressors only. 3-25 VOL I