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ELECTRIC WIRING.

CHAPTER I

INTRODUCTION.- INSULATION.- ANALOGIES.- THE

ELECTRICAL UNITS.

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ONE hears very often that this is an age of specialists. We are told time and again that all our thought and endeavour must be given to one branch of work, if there is to be any advancement. Yet it seems quite as true that there has never been a time when one must have so broad a knowledge. The development on all lines has been so great, and, in all branches of engineering, at least, these lines have become so interwoven, that one must greatly broaden interests and knowledge if the most is to be made of the special work. We may know only one thing, but we have to know about a great many.

Electrical engineering and architecture are certainly distinct, yet electrical matters are every year brought more to the architect's attention. Electric-lighting, the increasing application of the motor to elevators, pumps, ventilating-fans, etc., and the innumerable bells, burglar-alarms, gas-lighting arrangements and similar conveniences, have a rather important place in the equipment of buildings, and the electrical item is one of too much consequence to be turned over carte blanche to contractors or arranged for without due consideration. It is becoming important that the architect should know a little about the nature of electricity, the uses it can be put to, and what safe, economical, and durable electrical work is. Electrical power can be so cheaply and so conveniently brought into buildings of any size that there is no limit to its possible use. Already it is being seriously considered in connection with heating and cooking, and if the hopes of inventors are realized, the need for providing for the use of electricity and for looking most carefully into all electrical arrangements will grow into a necessity.

There seems to be an inclination to look upon all electrical matters as quite out of the range of ordinary work and interests, perhaps as something too mysterious to comprehend without that thorough study for which there is not time. But every architect knows something about plumbing, steam-heating, and gas, and the necessary knowledge about electrical matters is scarcely more occult. It would all be simpler if we but had an “electrical sense,” so that we might be impressed directly by electrical phenomena. As it is, much occurs without giving any evidence that can be appreciated by our five senses. When a wire is tapped here and there and a part of the electrical energy is translated into some other form that we recognize, such as light or heat, it seems an unreasonable and miraculous occurrence, for with our limited perceptions we cannot follow from cause to effect. When a little familiarity with the phenomena is acquired we are apt to forget the miraculous part just as we do on seeing an object drop toward the earth. We become content simply to give a name to the force. It seems to bring electricity nearer when it is thought how little we should know about heat for instance, if there were no sense of feeling. A good deal could be learned about it in a slow way, but its actions would be very mysterious. We should, perhaps, see a piece of wood suddenly blaze up, and a kettle of water a foot above it begin to dance about and boil, and yet we might pass our hands between the fire and the kettle with no appreciation of anything happening there. Steam might be carried from a closed kettle through a pipe to a small engine. The pipe might be of glass and nothing would be seen, so if we had no sense of feeling we should see only a piece of wood blazing, and a machine, with no apparent connection, doing work. This would surely not be less mysterious than the working of an electric motor.

Electricity is not an erratic, uncertain thing. The laws that govern electrical forces are well known, the forces can be controlled without great trouble, they can be measured with the greatest accuracy, and the way they will act under given conditions can be definitely foretold. Whatever electricity really is and whatever may ultimately be found true with regard to its nature, it is known that it acts very much as if it were a fluid, and all the actions of water flowing in a pipe are closely analogous to electricity “flowing” in a wire. We cannot go very far wrong when we look upor. it in this way, and as water flowing in a pipe is such a familiar phenomenon, a great number of useful analogies are at hand, and an easy way is open to understand many of the actions of electric currents.

In the earlier days of electricity, when trained workmen were scarce and the needs were not so well understood, and when, it might be added, the underwriters were not so hard upon the heels of the contractors, there was a great deal of exceedingly poor and slipshod work done. Electricity was fast getting the reputation of being most untrustworthy, if not actually dangerous. This idea is being dispelled under the improved conditions, and although much bad work is still done and most of the wiring is far from perfect, still it has been proved that even in the most difficult places, electricity can be employed with the greatest surety of action and

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