3 10 22 https://www.electrifying.collopy.net/files/original/a8d332a2c7eb29278de96e8dc5c6a768.jpg d9d95286aabd760d25b424025a197114 https://www.electrifying.collopy.net/files/original/be9472504f31f620a5544f6522b346fe.jpg 03e7662875d9d921d866620f077a5241 Still Image A static visual representation. Examples include paintings, drawings, graphic designs, plans and maps. Recommended best practice is to assign the type Text to images of textual materials. Original Format The type of object, such as painting, sculpture, paper, photo, and additional data Photograph Physical Dimensions The actual physical size of the original image 4" x 6 " Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Millikan-Sorensen Vacuum Switch Description An account of the resource Transmission of power is dangerous when high voltage drives immense amounts of current. When Big Creek finished construction, ultra-high voltage (up to 220 kV) was generated and ready to be transmitted [7]. Thus, significant safety challenges arose, specifically in regards to interrupting electrical arcs. The traditional oil circuit breakers that relied on oil to quench arcs faced growing problems such as fire risk, large size, and high maintenance [7]. Recognizing this, in 1923, Southern California Edison partnered with Caltech to build a high-voltage laboratory [4]. The photo above depicts all three switches that were developed and tested [8]. The bottom center shows the first prototype followed by the second on the left and the third prototype on the right. The large metal caps apart of the second and third switch were used to create vacuum-tight joints for the lead-in conductors [8]. The second vacuum switch was a larger version of the switch Sorensen and Mendenhall first tested [8]. From a 1926 paper by Sorensen and Mendenhall titled “Vacuum Switching Experiments at California Institute of Technology,” high success is reported as “the switch was operated as a single-pole switch to open and close this circuit more than 500 times without showing any burning of the switch contacts” [8]. It was even tested at the Torrence substation of the Southern California Edison Company where it was able to interrupt currents as high as 600 amperes at 12,780 volts [8]. Subsequently, the third switch was brought to Laguna-Bell substation where it was able to interrupt 926 amperes at 41,500 volts [8]! Works Cited [1] “100 Years Young: Big Creek Hydroelectric Plant Still Going Strong.” Edison International | Newsroom, https://newsroom.edison.com/stories/100-years-young:-big-creek-hydroelectric-plant-still-going-strong. Accessed 17 Mar. 2026. [2] “Power Lines Around Los Angeles: Isolation, Interconnection, and Aesthetics.” Boom California, 21 May 2020, https://boomcalifornia.org/2020/05/21/power-lines-around-los-angeles-isolation-interconnection-and-aesthetics/. [3] Fox, Donna, Robert J. McEliece, and Babak Hassibi. “An Electrifying Century: An Early History of the Caltech EE Department.” ENGenious, 8 Oct. 2010, engenious.caltech.edu/articles/history-EE-Department-century. Accessed 5 Feb. 2026. [4] Heilbron, J. L., and Robert W. Seidel. Lawrence and His Laboratory: A History of the Lawrence Berkeley Laboratory, University of California Press, 1990. UC Press E-Books Collection, https://publishing.cdlib.org/ucpressebooks/view?docId=ft5s200764&chunk.id=[section identifier]. Accessed 5 Feb. 2026. [5] Millikan, Robert A., and Royal W. Sorensen. Brief for Millikan and Sorensen. Robert A. Millikan and Royal W. Sorensen v. Talma T. Greenwood, Interference No. 56557, United States Patent Office, [Year, e.g., 1928], [Collection Name, e.g., Royal W. Sorensen Papers], [Box 3], Caltech Archives, Pasadena, CA. [6] Ornelas, Gabriela. “Big Creek’s Powerhouse 8 Marks 100 Years of Hydroelectric Power.” Energized by Edison, 8 Oct. 2021, energized.edison.com/stories/big-creeks-powerhouse-8-marks-100-years-of-hydroelectric-power. Accessed 5 Feb. 2026. [7] Record, Historic American Engineering. Big Creek Hydroelectric System, East & West Transmission Line, 241-Mile Transmission Corridor Extending between the Big Creek Hydroelectric System in the Sierra National Forest in Fresno County and the Eagle Rock Substation in Los Angeles, California, Visalia, Tulare County, CA. Still image. California -- Tulare County -- Visalia, https://www.loc.gov/pictures/item/ca3976/. Accessed 17 Mar. 2026. [8] Sorensen, Royal W., and Hallan E. Mendenhall. “Vacuum Switching Experiments at California Institute of Technology.” Transactions of the American Institute of Electrical Engineers, XLV, Jan. 1926, pp. 1102–07. Semantic Scholar, https://doi.org/10.1109/T-AIEE.1926.5061306. Identifier An unambiguous reference to the resource within a given context https://digital.archives.caltech.edu/collections/Images/10.33-29/ Source A related resource from which the described resource is derived Caltech Archives and Special Collections, High Voltage Research Laboratory Date A point or period of time associated with an event in the lifecycle of the resource 1924-1926* https://www.electrifying.collopy.net/files/original/b9d31c9accaffa6077f4ab4c155f129d.jpg 911fc00ada1afbfba375088417e5d3e5 Still Image A static visual representation. Examples include paintings, drawings, graphic designs, plans and maps. Recommended best practice is to assign the type Text to images of textual materials. Original Format The type of object, such as painting, sculpture, paper, photo, and additional data Photograph Physical Dimensions The actual physical size of the original image 8" × 10" Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource High Voltage Research Laboratory Creator An entity primarily responsible for making the resource G. Haven Bishop Source A related resource from which the described resource is derived Southern California Edison Photographs, Huntington Library Date A point or period of time associated with an event in the lifecycle of the resource 1929-01-14 Identifier An unambiguous reference to the resource within a given context https://catalog.huntington.org/record=b1868904 Description An account of the resource In 1923, Caltech and the Southern California Edison Company built the High Voltage Research Laboratory, the first university laboratory in the world to feature a million volt transformer. The building, sometimes called High Volts, was only the sixth building on Caltech’s new campus, so it was surrounded more by trees and lawns than by other laboratories. For its time, High Volts was an unusual partnership between a corporation, which supplied electricity and paid most of the $140,000 construction cost, and a university, which provided land. High Volts was architecturally bold: Internally, it was a single large room which held the massive transformer and other electrical apparatus. Edison engineers designed a steel frame, the second constructed in Pasadena. Architect Bertram Goodhue designed the exterior, which used a diamond pattern to provide texture in the absence of windows. Architectural sculptor Lee Lawrie produced a relief over the entry which represented the electrical research performed within. Brought together by members of Caltech’s board of trustees who also served on Edison’s board of directors, the two organizations would share the facility: Edison needed a laboratory in which to test high voltage electrical transmission equipment, including insulators and transmission lines which were later used to transmit electricity to Southern California from the Hoover Dam in Nevada. Caltech physicists, led by Robert Millikan, sought to use high voltage electricity to dismantle the nucleus of the atom. Millikan and his colleagues were not immediately successful in this effort, but in the late 1920s Charles Lauritsen and Ralph Bennett did use the High Volts transformer as a power supply to the world’s first 750,000 volt x-ray tube. A few years later, his student H. Richard Crane modified his own x-ray tube into a particle accelerator, and Caltech physicists joined the founders of the new field of nuclear physics.