In the November 1993 issue of Crown Jewels of the Wire, we showed pictures of a couple of very early suspension insulators that were made up of two pieces cemented together. One was made by Thomas and the other by Locke. Each style was cataloged in the 1910’s. The Locke suspension was marked with the VICTOR R=oo inside the insulator logo. Now a couple of earlier styles have been reported!!

Bill Rohde (NIA #1219) sent in some nice photographs of his 14-inch diameter, 2-part cemented suspension insulator. The cemented in petticoat is 6-1/2 inches in diameter and the glaze color is the typical speckled rust-brown found on early Victor marked insulators. This insulator was evidently made before the insulator logo marking was used. The marking is quite clear: VICTOR / PAT’D FEB. 25 ’08. As an example of perfect timing, I just received a letter from Mark Lauckner (NIA #4730) which included several photographs of nearly the same insulator with identical marking! The only difference is that Mark’s insulator has a longer split connector pin cemented in the bottom. Mark said his insulator was found in the vicinity of the Goldstream power plant in Victoria, BC. This is the location of the first British Columbia Electric Co. generating station. Look for Mark’s future article on the power plant in the Canadian Insulator Magazine.

The patent date in the marking is John Duncan’s patent No. 880,203. Look back on page 22 of the November 1991 issue of Crown Jewels of the Wire and you will see two old photographs which show how this type of insulator was assembled. The split connector ring, with eye formed on the end, fit into the cast iron cap of the unit below and was held in place by a bolt. These very heavy insulators probably weigh about 20-25 pounds each. In addition to problems with cement expansion which caused the porcelain to break, the 2-part construction produced an insulator that was not well balanced electrically. Also, the cap and pins suffered under the strain of the suspended cable and frequently pulled apart. The Duncan design was a failure and the cap and pin design was not perfected until a number of years later after the use of the Hewlett became widespread. It is amazing that any specimens of the early Duncan design have survived. Needless to say they are quite rare. In fact, any 2-part suspension is very rare indeed.

Victor 14-inch, two-part porcelain suspension insulator
marked with the Duncan patent date.
For size comparison, there is a CD 164 signal to the left.

Marking showing the
John Duncan’s patent date.

Bill Rohde’s insulator (above) and Mark Lauckner’s
insulator (below). Note the longer split connector pin.

The Pittsburg High-Voltage Insulator Co. was in operation from 1908 until about 1921. They turned out many hundreds of millions of insulators in more styles than any other company. Apparently insulator quality was not very important. The quality of their insulators was often quite low and notable for crudeness and non-uniform glazes on the smaller unipart styles. They evidently undercut prices of other insulator companies preferring to satisfy all customer’s needs no matter how small the order. Demand for electricity and telephone service produced a great need for insulators and Pittsburg was there to meet that need. An example of Pittsburg’s excesses at providing insulators to meet any customer’s demand can be found in their catalog No. 20 (circa 1920) where they offered 26 unipart styles and 28 multipart styles. How could they possibly produce so many different styles and maintain any sort of efficiency? Evidently their overextended product variety and quality control contributed to their downfall. Pittsburg also continued producing multipart styles with flared skirts long after other companies had realized these designs had problems with cement expansion and electrical imbalances.

Brent Mills’ book, Porcelain Insulators and How They Grew, mentioned that one company cataloged a 5-part porcelain insulator. That was such a foolish idea that I always thought it could not have been true. The suspension insulator had easily met the industry need for a satisfactory inexpensive insulator on high voltage transmission lines. I recently obtained a copy of Pittsburg’s No. 20 catalog and to my surprise the 5-part insulator dinosaur was offered! If it was actually produced, the cement expansion and electrical imbalances must have forced an early death for this design. There are size and cost limits for multipart porcelain insulators whereby weight, cement expansion, and electrical design make suspension insulators economically attractive, and the M-5000 design definitely exceeded all limits. This 20-inch diameter insulator (M-5000) was cataloged for 120,000 volts and weighed 100 pounds!

Large Image (142 Kb)

Jeff Kaminski (NIA #3582) reported a new style of multipart insulator that is almost as big as Pittsburg’s M-5000. This 18-inch diameter 4-part insulator is M-4820. The marking is a small insulator logo with VICTOR R=oo inside. This is perhaps the largest pin-type insulator known and weighs 80 pounds. The record for the heaviest insulator goes to Pinco’s M-4750 which weighs 92 pounds.

M-4820 with marking: Victor R=oo in small insulator logo
18 - 11 - 13 - 9.5 x 16

Fred Collier, Jr. (NIA #2933) reported several new unipart styles which we will get to next month; however, one of his insulators is so notable that I would like to tell you about it now. His insulator is similar to U-4 with the major difference being that it is slightly thinner looking. Fred first reported this insulator on the survey I sent him as having a light blue glaze with dark blue specs. Indeed, this is exactly what the glaze looks like. So, what makes this insulator so unusual? Only one other insulator has been reported with this glaze. Before Ken Willick’s report in the March 1995 issue of Crown Jewels of the Wire of a white U-376, only one specimen of U-376 was known and it has a light blue glaze with dark blue specs! This unique glaze is easily attributed to its manufacturer because the blue U-376 is clearly marked, LIMA, N.Y. Fred sent his Sim U-4 to me for a closer examination. Sure enough, it has the typical characteristics of a Lima made insulator: the pinhole is glazed and there is a near dime-sized impression in the top of the pinhole. I would be interested to hear from anyone who has an insulator with this same light blue glaze with dark blue specs. You can pretty well bet that all insulators with this unusual glaze were made by the Lima Insulator Co. (1904-1908).

Sim U-4 (left) and U-376 (right) with marking: LIMA, N.Y.
Both insulators have a unique Lima glaze consisting
of light blue and dark blue specs.