1901 - The Longest Transmission Line in the World

The Bay Counties Power Co. placed a line in service on April 27 that ran 140 miles, from the Colgate plant in the Sierra foothills to Oakland CA. The line used M-2795 Fred Locke “gutter-top” insulators at 40kV and delivered 3000 horsepower to the San Francisco Bay area

The insulators worked well when the weather was dry or after a good rain had cleaned the surfaces. But the fog was deadly. The electrical current would creep over the moist surface and heat the sulfur used to cement the porcelain top to the glass bottom. The molten sulfur ran down onto the crossarm, setting it on fire and often burning the entire pole down. The problem was particularly severe along dusty roads and near sources of pollution. In addition, because the insulator crown was “stuck on” to the insulator top when both were being formed from wet clay, many crowns popped off under heavy load. A larger and sturdier insulator, the rare M-2998, was used as a replacement for heavy loads.



[ <Back | Contents | Next> ]