Fire Hazard from Electricity.
This was the title of one of a course of lectures delivered a few weeks since at Cornell University by C.J. H. Woodbury of Boston. Certainly no man was better qualified to speak on this important subject. Protection against electric fires, like the applications of electricity itself, is making such rapid strides that one must be continually posting himself to keep abreast of the latest advances. What was true of the electric risk a few years ago is no longer true to-day. Old perils have been removed or reduced, new ones have been developed.
Glancing over this lecture and noting some of the present phases of this snbject, the first feature which strikes the reader is the extent to which the electric current has now been brought within control, and rendered with proper precautions among the safest of illuminants. The power for mischief is there as it is in the steam-boiler, but the conditions necessary to prevent the mischief are well understood. The danger of fire is almost entirely owing to the diversion of the electricity from the system through some outside circuit and to the inability of this circuit to carry the current without excessive heating. Moisture here plays an important part, especially if it be slightly impregnated with lime or salt. The moisture then becomes an active conductor, and with its ready dissipation the mischief follows. So long as no ground connection exists, no injurious results may follow such an outside connection ; the electricity may prefer to adhere to the original conductor. But if anywhere such a ground connection has been formed, the new conductor even though imperfect is likely to establish a short circuit and thus receive the current. Another feature too often overlooked is the effect of insulating material. Such material, of course, resists the escape of the eurrent. That is its object, but this very resistance tends to generate heat, and without due precautions the material used for protection becomes a source of danger. One other point to be noticed is the importance of regulating both the flow and the ability to dispose of it safely in case of a dangerous accumulation of heat or electric energy. In all these respects have important advances been made, so that like the steam engine, while the danger elements are present to-day perhaps to a larger extent than ever before, they are under “vastly better control, and the risk of accident has been and is continually being reduced.