Thomas Charles Gilbert
Thomas Charles Gilbert, MIEE
1888 born in Folkestone on 8 February.
Apprenticed to T. W. Southee.
WWII Served with the Royal Engineers at the Cinque Port fortresses
1919 he founded his own contracting firm, T. C. Gilbert and Co.
His main interest was in earthing and protection, an area in which he became a recognised expert.
As the use of domestic and portable appliances fed from AC mains grew, so did the risks of fatal shock, and Gilbert realised that insulation could only provide partial protection. This led him to study continental wiring systems, particularly that of Germany. He began a close correspondence with the Rheinish-Westfalishces Elektrizitatswerk (RWE) who provided electricity for the Ruhr, and whose engineers had developed advanced earthing systems. Of special interest to Gilbert were the earth-leakage circuit breakers that RWE used. These were manufactured by Schiele & Bruchsaler-Industriewerke AG (SBIK) to a design by Ernst Besag, who also did consultancy work for Siemens. Gilbert was convinced that the use of earth-leakage circuit breakers was the best way to ensure protection against shock and he began to work to get them introduced to Britain - indeed he told RWE that the idea of protective switching should be promoted even though the market did not yet exist.
Gilbert championed the use of earth-leakage circuit breakers through his work for the BSI and the IEE Wiring Regulations Committee, and he became a major voice in what became known as the "earth or insulate" debate.
1932 Gilbert published 'Artificial Earthing for Electrical Installations'
1934 The 10th edition of the IEE Wiring Regulations made leakage switches compulsory in cases where the earthing resistance exceeded 1 ohm.
1934 Gilbert was investigating the possibility of a formal agreement with RWE and SBIK to promote their switches in Britain, and he visited the Ruhr in 1936 and 1937 to see RWE installations.
It was the 1936 visit that fired his interest in non-metallic wiring conduits. He was already concerned about the use of metal conduits as earthing conductors, especially the fact that conduit connectors could prove unreliable conductors. Non-metallic conduits were quite common in Europe, particularly in Italy and Germany, where a system called Protoflex was in widespread use. RWE used conduits reclaimed from industrial waste rubber.
By 1939 Siemens and J. A. Crabtree and Co had switches on the market, although manufacture of protective switches was limited in Britain. Other firms involved in protective switch manufacture included Reyrolle Ltd and Nalder Brothers and Thompson, who manufactured switches using connections patented by the RWE engineers.
WWII Gilbert set about developing his own system for non-metallic wiring conduits, leading to a patent in 1943, while he was serving with the Royal Engineers, as Garrison Engineer at Thetford with the rank of Captain.
1941 His system was designed to work with Crabtree protective switches. Even before he had received his patent, Gilbert was thinking of the manufacture and sale of his system, and to this end he approached the North British Rubber Co in 1941. NBR agreed to develop Gilbert's system, which became known as Gilflex
1946 North British Rubber set up a subsidiary company, Flexible Non-Metallic Conduits Ltd. Gilbert was appointed as Managing Director.
1951 Gilbert's partnership with NBR was an uneasy one and by 1951 he decided that he could develop Gilflex better on his own, so he, his wife Dorothy and his sole assistant Rowland Hardy set up Gilflex Conduits Ltd with limited share capital subscribed by their family and friends.
The contracting industry did not embrace non-metallic conduits as rapidly as Gilbert might have hoped. However, sales did grow gradually and in 1959 Gilflex was able to pay off its debt to its manufacturer, Erinoid Ltd.
Thomas Charles Gilbert was an engineer of immense energy who was devoted to the industry. As well as his championing of earth-leakage circuit breakers and non-metallic conduits, he was a tireless contributor to the trade press, and he became a familiar name in many electrical journals. Towards the end of his life he had completed a second book, 'The Application of Earth Leakage Protection to Low- and Medium- Voltage Circuits' although this was never published. He contributed regular columns to The Electrical Contractor, The Electrical Times, The Electrical Review, Electrical Industries Export (as 'Continuity') and 'Building Industries and the Scottish Architect'. He often entered into lively correspondence with those who disagreed with his often forthright views. Much of his writing was from a practical point of view - he accepted that amateur and DIY electricians were a fact of life and he wanted to ensure that the equipment and wiring they used were as safe as possible.
He was an active member of the Electrical Contractors' Association, serving on its council, and he served on the Advisory Committee of the City and Guilds of London Institute. He also contributed to the work of the BSI, notably Committee ELE80 on non-metallic systems.
1958 Gilbert died suddenly on 28 June, just as Gilflex's sales were improving. He was succeeded as Managing Director by Rowland Hardy, with Dorothy Gilbert taking over as Chairman and continuing as Secretary.