Insulators

Noel Dawson

In the history of Communications, the invention of Telegraphy was as momentous in the mid l9th Century as electronic communication is in today's era of technology.

Prior to Telegraphy, distance communications were effected by such diverse methods such as Native Drums, Message Sticks, Smoke Signals, Heliograph, Carrier Pigeons and Semaphore. The introduction of Telegraphy meant a message could be conveyed along a copper or galvanised iron wire by an electric current. The wires were bare and without the advent of Insulators there would have been leakage of current at every contact point along the route and the message would never have reached its destination. Hence the birth of Insulators and they had to be effective at all levels of humidity and in all types of weather.

Samual Walker McGowan was commissioned by the Victorian Government to build Australia's first telegraph line to run a distance of 11 miles between Melbourne and Williamstown and the first message was sent on 3rd March 1854. The line was extended to Geelong by Dec. 1854 and due to a shortage of Insulators McGowan had to improvise by making his own from Tar and Shellac.

Other States soon followed Victoria's lead resulting in lines being established between Adelaide - Melbourne (July 1856), Melbourne - Sydney (Oct. 1858), Hobart - Melbourne (1859), Brisbane - Sydney (Nov 1861), Adelaide - Darwin (Aug. 1872) and Adelaide - Perth (Dec. 1877) . It is known that the Sydney - Brisbane line used some porcelain insulators supplied by the Rabone Feez Co. in Sydney whilst the Adelaide - Perth line used insulators from the Berlin Pottery Works. These early lines used porcelain insulators, some designed by Charles Todd (Adelaide - Darwin line) and others were clad by an iron outer shell to protect the insulators from being broken by Aborigines for use as cutting implements.

Insulators have been made from a variety of materials including wood, clay, porcelain, glass, ebonite, asbestos composite and plastic. In general the majority of insulators were made either from Porcelain or Glass. American glass insulators were extensively used along South Australian Railway communication lines with Hemingray, Lynchburg and Whitall Taturn insulators being used. Brookfield insulators from America were used along Melbourne Tramway lines and American Pyrex insulators along some Victorian Railway lines. French Isorex insulators were used on lines in the Eastern States and may still be seen in use along some power lines. The large Isorex dark olive green bell shaped insulator designated by the identification number CD 494 is very rare and sought by collectors. It is believed to have been used on phone lines in the Riverina area of NSW and the Western District area of Victoria in the mid 1930's.

By painstakingly measuring and photographing insulators, a numbering identification system was developed in America for world wide recognition of the different types available. For Glass insulators, the letters %W prefix the number whilst for Porcelain insulators the prefix is "U". American books are available which give graphic profiles, cross sections and dimensions of the wide array of %W and "U" type insulators.

There is little documented evidence of Australian Insulator manufacturers but the following comprises some of what is known.

Australian Glass Insulators

Edward Roberts established a small glass works on the shores of Lake Tyers in Gippsland, Victoria and produced some 100,000 aqua blue CD 121 toll type insulators embossed PMG between 1912 -1915 for use on telephone lines in Victoria and NSW. These insulators are considered very rare and only a handful are known to still exist.

The Australian Glass Manufacturer's (AGM) first made insulators in the 1920's from a toughened glass similar to Pyrex glass under the name AGEE and produced types such as CD 490, CD 121, CD 154, CD 420, CD 421, CD 421.1 and CD 422. The CD 154 was a copy of the American Hemingray CD 154's being used in South Australia. Around 1940 AGM merged with Crown Crystal Glass (CCG) and they assumed responsibility for insulator manufacturer and produced CD 422, CD423, CD430 and CD 432 glass insulators. The CD432's were introduced as an experimental insulator to compete against porcelain insulators and were only used on the Melbourne - Dromana line in 1938 but were unsuccessful. Only five are known to still be in existence. In the early 1950's AGM resumed control of insulator manufacture at their Hobart plant and continued to produce CD 423, CD 430, CD 590, CD 1054, and CD 1055 type insulators. Manufacture continued up until the early 1960's before it was considered uneconomic to continue insulator manufacture.

Australian Porcelain Insulators

During the early years of the Telegraph, porcelain insulators dominated the wires and there were numerous Australian manufacturers. Types produced were the "U" types such as 1154, 1145, 1160, 1148, 1491, 1493, 1497, 1500, 1502, 1503 and 1504. Australian companies who produced porcelain insulators included the following: R.F.Fowler and Fowler Ltd. (Sydney), F13 (thought to be Fire Brick Co.- Melbourne), Sunshine (Melbourne), Welland (Adelaide), Koster Pottery (Adelaide), Slaters Acme (Melbourne), Rabone Feez (Sydney), Bennetts (Adelaide), NPA (Nilsons Pottery - Melbourne) and Morland Industries (Melbourne).

It is possible Slaters Acme may have imported their insulators from overseas as they were also an agent for Oppenheimer telephone/telegraph equipment. Today, Morland Industries remain the sole manufacturer of insulators in Australia and continue to manufacture power line transmission insulators at their Yarraville plant in Melbourne.

Many of the above types of insulators were also imported from countries such as England, (mainly Bullers) Italy, Czechoslvakia, Russia, Switzerland, and in more recent years as it became uneconomic to manufacture in Australia, from countries such as China, Japan and New Zealand.

The success of the U 1145 -1148 type insulators and the Ul 461 and 1163 styles imported from overseas finally saw the demise of glass insulator manufacture in Australia.

Colour of Glass Insulators

The basic components of glass are sand, soda and lime. The sand contains various amounts of iron oxides and it is these impurities that give the glass a greenish blue tinge of colour. The addition of manganese oxides help to produce a clear glass but exposure to Ultra Violet light tends to turn the glass purple. Selenium also helps to produce clear glass but if the molten glass is cooled too quickly it produces a pinkish colour tinge. Selenium containing glass will turn straw or yellow coloured on prolonged Ultra Violet light exposure.

Most glass insulator manufacturers also used a proportion of recycled glass, referred to as Cullet, in manufacture, and the final colour of the insulator depended upon the amount and colour of the cullet which was used. Many of the Australian Glass insulators are prized amongst collectors for their rich colours.

Insulator Collecting

Insulator collecting is now a world wide hobby, mainly centred in the USA but is rapidly becoming more popular in Australia. Insulators are an item of History as in this modem era of communications telephone wires have been replaced by various underground cables. Most of the above ground poles containing insulators have been removed and the insulators trashed, much to the dismay of collectors. Glass insulators because of their spectrum of colour's are the most popular but there are also many different coloured and attractive porcelain insulators.

Where to find Insulators

Old disused lines in remote county areas, bric-a-brac shops, old buildings and Swap Meets are all good places to look for insulators. Many references and sale lists can be found on the Internet. Believe me, nothing looks better than the sunlight shining through your insulators when they are sitting on your windowsill. Start now and collect some of Australia's colourful history. If you require further information on Insulators or Insulator Collectors in Australia feel free to contact me at the above e-mail address.

URL: http://www.ahts.org.au/ndArt1.htm
(Modified:April 15, 2011 12:08 PM)