In July 1999, we discussed two rather large wall entrance tubes. The white tube was about two feet long, six inches in diameter and dated 1906. The smaller brown-glazed tube was nearly three feet long and 2-1/2" in diameter. It had the "THOMAS" marking on one end. We now know that this is actually the inner tube of the wall entrance tube similar to that shown in the illustration from the 1920 Thomas catalog. Wall entrance tubes were used to insulate the high voltage conductor cable as it passes through the wall of a substation. The photograph shown on the following page from the 1925 Locke catalog shows several conductors entering the substation through wall entrance tubes mounted in the upper part of the outside wall.

Illustration of Thomas wall entrance tube from the 1920 Thomas catalog. 
Note the long slender inner tube through which the high voltage cable passes.

This photograph from the 1925 Locke catalog shows wall
entrance tubes mounted in the brick wall of a substation.

The first wall entrance tubes were made from 12" sewer pipe tiles. This worked well for up to 10,000 volts, but higher voltages required greater insulating qualities. Fred Locke patented the original design for wall entrance tubes. Patent No. 870,187 was granted on November 5, 1907. The design is similar to more modem tubes with a porcelain tube to carry the conductor cable and one or two porcelain disks in the center. Fred Locke's second patent, No. 878,646, was granted on February 11, 1908. This novel design was made up of two or more concentric tubes cemented inside each other. The tubes provided petticoats that effectively increased the leakage path much like petticoats under a standard pin-type insulator.

Mike Spadafora found three wall tubes about a year ago in an old substation in the northwest that were made based on Fred Locke's 1908 patent. The tubes were mounted in a wooden panel set in the wall and held in place on the inside by a galvanized metal band fixed around the outer tube. These are rather small tubes composed of three concentric porcelain shells cemented together. The design is very strong and provides a very long electrical leakage path. Unfortunately, none of the tubes were marked but the glaze was obviously early Locke circa 1905.

Locke catalogs offered this type of tube for many years. Some consisted of up to seven tubes and the largest size weighed 240 lbs! Usually wall entrance tubes are cemented into a brick or concrete wall. This type of wall entrance tube was designed to be mounted in a panel of varnished wood, slate, marble, or glass. The specification called for the panel to be twice the diameter of the insulator.

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Fred Locke style wall entrance tube from 1910 Locke catalog.

Early Locke wall entrance tube (circa 1910) 
found by Mike Spadafora.

Many of you know Ken Willick (NIA #3709) who lives in Fred Locke country at Lima, NY. Ken likes to dig in the local Fred Locke dump in nearby Victor and usually comes up with some very interesting items. I'm a bit late reporting this but Ken's digging a couple of years ago turned up a whole host of interesting and varied insulators. Unfortunately, most were badly damaged. On one of his hunts, Ken "stumbled over" a previously unknown dump site. His first clue was an unmarked U-441A sitting right out in the open. Quickly raking the area and digging around yielded many shards and a few decent specimens of U-4, U-108, U-196, U-259, U-330, U-441A, U-608, U-611A, U-639, U-648, U-669, U-925, U-949, U-954, U-957, U-964, and a large variety of early multipart pieces all from the Fred Locke era. He also found a specimen of U-520 with a "VICTOR" incuse marking. This is the only known example of this style that was shown only in the 1910 Locke catalog. In addition, Ken found an unusual broken piece that has threads on the outside and was obviously glazed below that. This appears to be one of Fred Locke's early suspension insulators made based on patent No. 779,659 (January 10, 1905). Here are a few photos of Ken's dump finds.

Fred Locke dump items: 
U-108 N-N, top to Fred Locke suspension, 
U-330 "P. M. Locke", and U-330 N-N

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Fred Locke dump items: 
U-648 N-N, U-520 VICTOR, and U-669 N-N.

Fred Locke dump items: 
U-441A F. M. Locke, U-196 "B-7-2" under-glaze ink marking, 
U-4 incuse "F. M. Locke" with white glaze, 
and U-639 "F. M. Locke" marking.

Ken reported one more interesting rare insulator he purchased for his collection. It is U-560 with tan glaze and Imperial Porcelain Works marking. It also has a manufacturing date around 1903 or 1904. Fred Collier, Jr. (NIA #2933) has one with the Imperial crown logo marking. These are the only two brown U-560's known with Imperial markings.

U-560 Imperial with metallic tan glaze.

If you are interested in multipart, unipart, and glass insulators that were used on early power transmission lines and old power plants, you should subscribe to Ed Sewall's new Power Line Explorer Journal. The journal will encourage those actually out researching and hunting early lines to document their finds, regardless of how small. Each issue of Power Line Explorer Journal will contain several detailed articles on searches of early power transmission lines, hydroelectric plants, old substations, mines, dumpsites and any other place insulators were used. Additionally, articles documenting historical research from enthusiasts around the country on insulators and early power transmission systems will also be published in this journal. Early porcelain and glass power line insulators as well as associated items such as pins, wall tubes, conductors, pole line construction etc. will be the focus of the articles. Several regular columns are also anticipated to be featured in future issues. Enjoy the history and thrill of the hunt! The Journal is highly recommended.

Contact Ed Sewall if you would like to subscribe
(annual subscription $6). (E-mail: plej@insulators.com) 
(see ad on page 35 of this issue)