Insulators Home > Insulator Styles > Porcelain Multiparts > M-2795
Manufacturer: Locke
Mnfr Code: 316
Date: 1900 - ?
Colors: Tan, White
Usage: 44 kV - 60 kV
Elton Gish's Multipart Porcelain Insulators book gives dimensions of 11.5 inches tall, 10.5 inches top skirt diameter, and 6 inches base diameter.
The NIA Timeline says on December 18, 1900, Richard H. Sterling of Pittsfield, Massachusetts received a patent for "a multipart insulator with an eves-trough that was implemented in M-2795. This patent was filed earlier than Fred Locke's May 29th design patent, and there is an interesting story about this in Elton Gish's book: "Fred M. Locke, A Biography". This is US Patent 664,301. The NIA timeline also has a page about the M-2795 that shows a "Locke No. 316 M-2795 insulator which combined a glass base with a two-part glazewelded porcelain top", which was "the first true high-tension multipart insulator and was used at 44,000 - 60,000 Volts".
The Insulators.info Glossary says the "feature around the outer edge of the top skirt of Fred Locke styles U-969, M-2335, M-2335A, M-2785, M-2795, M-2796 which collects and channels rain water to one or two spouts" is called an 'Eaves-trough'.
Insulators.info's Porcelain Photo Gallery says "The first multipart dates to 1900 when Fred Locke designed M-2795 for the Bay Counties, CA power line at 60,000 volts. The highest previous line was limited to 30,000 volts!"
Elton Gish's Fred M Locke page shows the only known M-2795 with a white top, which was manufactured on December 7, 1900.
Insulators.info's White M-2795 page says the white gutter-top "is the style that Fred Locke proposed for the first 60,000 volt transmission line ever built. The porcelain top was to improve puncture strength and the glass base was for flash-over protection. This is the only known white one.". It lists an estimated value of $1580 to $2140.
Insulators.info's Tan M-2795 page says the tan gutter-top is "the more common twin of the white M-2795. These were used on the Bay Counties California line for a few years until they were replaced by larger four part styles. Some were reused at a lower voltage in Hawaii!". It lists an estimated value of $240 to $360. The dimensions given are 11.5 inches tall, with a 10.5-inch diameter for the top and a 6-inch diameter for the base.
The 2003 Open-Wire Insulator Auction showed those values are rather low; it placed an estimate on a tan gutter-top (manufactured in Victor, New York on December 4, 1901) at $700-850, with a reserve of $650, but it ended up selling for $1350! The item page (no longer available) mentioned "We've heard collectors affectionately refer to these as the 'eave trough', 'eave spout', 'gutter top', and 'porcelain/glass Locke'."
Elton's Multipart Porcelain Insulators book contains "many photographs of northern California lines that used Fred Locke M-2795s" and,"a previously unknown photograph of the M-2795 assembly yard".
An article by Howard Banks of the Jefferson State Insulator Club on the Rogue River Electric Company states that "an 18 mile stretch of the Rogue River Electric Company line from Grants Pass to the Green Back mine in Northern Josephine County" in Oregon used "a handful" of M-2795s, and "a three-mile long branch of the line that ran to the Granite Hill Mine used M-2795s almost exclusively". He also says, "The glass and porcelain two-parters were being replaced in California by 1904 when it was discovered that electrical leakage would melt the sulfur cement that held the two parts together. The insulators were self destructive. The molten sulfur would fall onto dry grass in the summertime, setting the grass on fire."
Spencer Howard had a display including an M-2795 at the 1996 NIA Central Region Show. Mike Doyle and Mike Spadafora brought one, with its original pin and part of the wood pole, to the JSIC's 2003 Rohde Ranch BBQ. Bill Ostrander recovered some pieces from a dump circa 2000.
Mike Spadafora and Bill Rohde displayed an M-2795 complete with porcelain pin sleeve at the 2003 Western Regional. As of 2003, here are only three intact pin sleeves known.
Paul Greaves and Denley Bryson are, as of February 2004, in the process of digging "an old insulator dump near the historic Colgate to San Francisco power line", and piecing together the many fragments they found, estimated to have come from at least 225 different insulators. The dump is actually located in Denley's yard, and boxes of pieces in the process of being sorted through have filled up an unused large section of his driveway. About 95% of what they found were M-2795 pieces. There is a long series of photos in the Insulators.info Picture Album.
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Contact: A.C. Walker