Electrical control of dangerous machinery and processes

A number of accidents occur with dangerous machinery and processes, which though not of an electrical character, such as electric shock or burns, are due to the failure of electrical control equipment, or could have been prevented by the use of suitable electrical control or protective gear. This paper discusses such matters in as systematic a manner as their varied character allows. Typical instances are interlocking of danger areas, design and adjustment of limit switches, safety equipment on cranes and lifts, pushbutton circuits and the prevention of inadvertent starting of dangerous machines. The dangers from fire risks have been dealt with in an earlier paper in association with Mr. F.H. Mann, and the author has given some account of furnace control elsewhere. The author would point out that the conclusions and suggestions set out below are his own. They are relevant to the present stage of development of electrical control, and are subject to modification in the light of further experience. They do not necessarily represent the views or considered policy of his Department.