HISTORY OF THE Southern Sierra Power Company "OPEN" LINE REFERRED TO AS THE "O" LINE

The "O" line is a single-circuit 115 kilovolt power transmission line built in 1929 by the SOUTHERN SIERRAS POWER COMPANY. It originally ran between a then-prominent steam generating power plant at Seal Beach (near Long Beach) California, and a major power switching substation in San Bernardino. The old line's route runs through the Chino Hills State Park entering on the south end near Yorba Linda and on the north near the parks main Ranger station near Colton. The "OPEN" line was constructed as an emergency power interconnect between Los Angeles Gas & Electric Company and the Southern Sierras Power Company. The power line was only energized during emergency power transfersâ€"thus it's "open" designation. Interestingly, within a few years of it's completion, it was energized after the 1933 Long Beach earthquake destroyed a portion of the LAG&E Seal Beach steam plantâ€"then the main supplier of electric energy for that area. The original reason that this long distance transmission interconnection was built was that SSPC and the LAG&E were both generating power at 60 cycles, while other closer utilities around San Bernardino generated at 50 cycles. Expensive cycle converters were limiting and technology had not yet produced one which could handle intended interconnection capacities desired. The "O" line terminated at the very San Bernardino substation where another power line, built later in the 1930's for the construction of Hoover Dam, originated. It contributed to the overall reliability of construction power on that major Colorado River dam.

Towers were a direct burial type and the conductors were a copper alloy. Few of the original towers (shown) remain today (except at the Thorne residence in Oak Creek Canyon, AZ), however most still remain intact on the Chino Hills Park right-of-way.

This tower is in my back yard in northern Arizona near Sedona. I use it to train linemen, and also as a testing tower for rescue equipment. I have the original JD blue porcelain insulators on the tower that were originally used.