Performance tests on moulded lampholders

Questions have arisen, from time to time, as to the performance of moulded composite lampholders under severe conditions of service; also as to their ability to comply with official rules and regulations. In an endeavour to answer these questions and to furnish the Wiring Regulations Committee of the Institution with authentic performance data, the Association carried out an experimental investigation on a range of representative specimens purchased through the ordinary commercial channels during the latter half of 1929. The results, which are of a reassuring character, are given in the present report, together with other relevant information kindly placed at the disposal of the Association by the British Thomson-Houston Co., Ltd., and the General Electric Co., Ltd. Various types of moulded lampholders were obtained through ordinary commercial channels and examined under a number of extreme conditions which, for the most part, were based on, or made to represent, all known or assumed service hazards. The tests were made to represent the severest conditions under excess current, over-voltage, fire hazards and faulty manipulation. Details of individual performance under these conditions are given in Tables 2 to 6. The investigation leads to the conclusion that moulded insulation can be, and, in fact, is being, employed in the manufacture of lampholders without practically affecting the electrical or fire hazards. The tests described on page 167 lead to an improvement in design which can be incorporated without difficulty.