1908 Duncan patent suspensions in service

By Mike Spadafora; posted April 1, 2007

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This is an orignal photo of the first (as far as I know) 100kv line built . It was also the forst steel tower suspension line ... The grandfather of all modern suspension type construction steel tower transmition lines . the line ran from the Stanaslause Powerhouse to San Fransisco and wad built in 1908 . The huge fragle thin insulators were each 14" across making them one of the largest suspension insulators ever used . they failed miserably from lightning flashover, cement expansion causing cracks in the porcelain and failure of the cap castings dropping the line. They are a cemented two part insulator, the inner skirt being a seprate piece of porcelain. they are extreamly rare in collections today. Please see the next picture in this album for a close up of the tower top. Here is a link to a picture of this insulator that was recently found on the line [id=180017664]