Stobie pole

A Stobie pole is a power line pole made of two steel joists held apart by a slab of concrete. It was invented by Adelaide Electric Supply Company engineer James Cyril Stobie (1895–1953). Stobie used materials easily at hand due to the shortage of suitably long, strong, straight and termite-resistant timber in South Australia.

In July 1924 the patent application for the pole design was submitted in both English and French, and accepted in November 1925. Stobie described his invention as

"an improved pole adopted to be used for very many purposes, but particularly for carrying electric cables, telegraph wires... [it] consists of two flanged beams of iron or steel, preferably rolled steel joist of 'H' or of channel sections, placed one beside the other with their flanges inward and preferably at a very slight angle one with the other and held together by means of tie bolts, the space between them being filled with cement concrete."

Stobie and John Brookman were so confident of the new pole that they formed The Stobie Pole Syndicate for the purpose of patenting the design and then selling the patent or manufacturing rights. The Hume Pipe Company became their first agents and, while there were numerous international enquiries, South Australia has largely remained the only place where they are widely used.

Stobie poles are reasonably common in Broken Hill, New South Wales, as well as the Darwin, Northern Territory CBD and a few thousand are installed across Tasmania. A few also exist in isolated settlements in the Goldfields-Esperance region of Western Australia such as Eucla and Rawlinna.

The first poles were erected in South Terrace, Adelaide in 1924, and were then used extensively in building the electricity transmission and distribution infrastructure throughout the state. The Stobie pole was central to the speedy expansion of Adelaide Electricity Supply Company's supply. It was cheap and simple to produce, had a uniform appearance, saved an enormous amount of timber from being cut down, had a long life expectancy and, at the time, was seen as more environmentally sensitive.SA Power Networks review alternative pole designs available on the market and has yet to find one with the benefits offered by the Stobie pole.

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