Electric wire

“ Whenever possible, the wiring of a house, etc., for bell work, should be done as soon as the walls are up and the roof is on. The shortest and straightest convenient route from bell to battery, etc., should always be chosen where practicable to facilitate drawing the wire through and to avoid the loss of current which the resistance of long lengths of wire inevitably entails. The wires should be run in light zinc tubes nailed to the wall. ”

“ The finer the wire, the more its resistance. The large wire that you see on the poles connects directly with this fine relay wire. When the electric circuit is complete, the soft iron bars are magnets; when it is broken, they are not. Thus is produced a backward and a forward movement of the armature which opens and closes a second or local circuit, in which is placed the sounder, having two similar coils, but wound with comparatively coarse wire. ”

“ Inductance increases with the frequency of the current in a conductor, and in each of the three systems just considered the frequency is sixty cycles per second.
The use of one circuit of larger wire instead of two circuits of smaller wire has the obvious advantage of greater mechanical strength in each conductor, saves the cost of one pole line and of the erection of the second circuit. With voltages above 40,000 to 50,000 on long transmission lines there is a large loss of energy by leakage directly through the air from wire to wire. ”

“ In general wiring, use weatherproof office wire, or, better still, well-made electric light wire. For ordinary house work No. 16 B. & S. gauge is preferable; smaller wire means higher resistance and less current at burner. For braided office wire, No. 16 runs about 95 feet to the pound, No. 18 about 135 feet to the pound. The cheaper grades of wire without the patent finish or extra insulation are not worth using; sooner or later trouble will ensue, [Pg 37] and once a house is wired, it is no pleasant job to hunt trouble, especially if the wire was put on before the plaster. ”

“ The insulated wires being drawn into them, any short circuit or heating of the wire cannot give rise to a fire, as it can only take place in the interior of a non-inflammable tube. A third system of electric light wiring is the safety concentric system, in which concentric conductors are used. The inner one, which is well insulated, consists of a copper-stranded cable. The outer may be a galvanized iron strand, a copper tape or braid, or a brass tube, and is therefore necessarily connected with the earth. ”

“ The electric light company will supply a sufficiently large wire from transformer to switch; the firm does the remainder of the wiring.
FEEDERS. From this large double-pole switch (which is the main cut-off) radiate “feeder” wires to the various parts of the building, to supply the lamp circuits. These feeders have to be carefully gauged according to the number of lamps, or rather, amperes, they are required to carry, in order to avoid resistance in the wire; or in other words, must not crowd the carrying capacity of the wire, or the resistance will make the wire hot and might cause fire. ”

“ How quickly a spoon inserted into a hot cup of tea becomes uncomfortably hot, though the hand can be held very close to the liquid without feeling more than a gentle warmth. And we all have noticed that the very least air-gap in an electric circuit effectively breaks a current capable of traversing miles of wire. If the current is so intense that it insists on passing the gap, it leaps across with a report, making a spark that is at once intensely bright and hot. Metal wires are to electricity what speaking tubes are to sound; they are as it were electrical tubes through the air and ether. ”

“ In the first place we must have a large number of these wire loops, and as the wire is soft and easily bent, we must wind it about a core so as to hold it rigidly in place, as it has to be revolved very rapidly. Again, the ends of each wire loop must be brought out and attached to plates or blocks of metal, arranged upon some kind of non-conducting substance at one end of the shaft upon which the whole will turn. ”

“ If the current is broken, the filings fall from the wire, and only so long as the current flows through the wire does the wire have power to attract iron filings. An electric current makes a wire equivalent to a magnet, giving it the power to attract iron filings. ”

“ If the shaft which supports the loop is rapidly revolved; a current of electricity will be set up in the wire loop by bridging over the space at the ends of the wire between the metal plates with a piece of metal or another loop of copper wire; copper always being used to conduct electricity where it can be, for the reason that it is the best practical conductor of electricity. ”

“ They shall not move the machine while the cutter chain is in motion. When connecting the power cable to the electric wires, they shall make the negative or grounded connections before connecting to the positive, and when disconnecting the power cable, shall disconnect from the positive line before disconnecting the negative or grounded. When positive feed wires extend into rooms, they shall connect such wires to the positive wire on the entry before connecting the power cable, and as soon as the power cable is disconnected shall disconnect such wire from the wire on the entry. ”

“ You must remember, to begin with, that in referring to wire used on magnets and armatures and for carrying the electricity away to the lamps, we always mean wire that is covered or insulated. In electric lighting, insulated wire is always used, except at the points where it is connected with, the dynamo, the lamps, a switch, or any point where we make what is called a "connection." ”

“ Wires were then run from the lamp socket through the cork and wood disks and the whole painted with melted paraffin to close all apertures and keep out moisture. Good rubber-covered electric-light wire will do nicely for the wiring outside the house, although, if it can be obtained, a piece of lead-covered paired wire is preferable. These wires must be only long enough to reach inside the house, where they may be joined to the ordinary sort of wire used in electric-bell work for connecting with push button and battery. ”

“ It sometimes happens that after using power from the local electric illuminating company for some time, conditions arise which make it expedient for the owners to install a private electric plant. If a straight three wire system had been originally installed, the mains and the feeders when used on a two wire system would not be heavy enough by 25 per cent., as the neutral wire of a straight three wire system is the same in size as one of the two outer wires, and theoretically carries one-half the current or less. ”

“ The wire has capacity with respect to the earth, and it acts like the inner coating of a Leyden jar, of which the dielectric is the air and ether around it, and the outer coating is the earth's surface. When the discharge takes place, we may consider that electrons rush out of the wire and then rush back again into it. At the moment when the electrons rush out of or into the aerial wire, we say there is an electric current flowing into or out of the wire, and this electron movement, therefore, creates the magnetic flux which is distributed in concentric circles round the wire. ”

“ These wires are connected with the brushes of a commutator, K, on the engine-shaft, which commutator is in electrical connection with the poles of a battery, dynamo-electric machine, or other source of electricity. Instead of two wires to produce a spark, a single wire may be arranged to become incandescent at the proper time for ignition. ”

“ This continual making and breaking of the circuit keeps up as long as the push is pressed, a ball mounted on A by means of a rod strikes against the gong G causing a continuous ringing of the bell. The wires leading between the bell, battery cell and push must all be insulated, that is, covered with cotton, rubber, etc., which prevents the leakage of current should two wires cross each other. Copper wire is mostly used for circuits indoors, the details of the kind and size of wire will be given later on. ”

“ It is very easy to detect the electric lines which radiate from every part of such a wire when a spark jumps between the terminals S of the coil. All that is necessary to do is to pass the wire through a sensitive film and to develop the film. The accompanying photograph (Fig. 3) was taken at the top of such a wire, by means of a very powerful apparatus at my command. When the photograph is examined with a microscope the arborescent electric lines radiating from the wire, like the rays of light Fig. 2a represents a more complete electrical arrangement of the receiver circuit. ”

“ To do this, rub it on a permanent horse-shoe, or other magnet, until it will attract an ordinary sewing needle strongly, or wrap it up in several turns of insulated line wire, and send many jerky charges of electricity from a strong battery through the wire. When it has been well magnetised, mount it on a spindle of fine hard wire, and secure it by a drop of solder. ”

“ Experiment 70. Turn on the switch that lets the electricity flow through the long resistance wire that passes around the porcelain posts. Watch the wire.
The resistance wire you are using is an alloy, a mixture of metals that will resist electricity much more than ordinary metals will. This is the same kind of [pg 232] wire that is used in electric irons and toasters and heaters. It has so great a resistance to the electricity that it is heated red hot, or almost white hot, by the electricity passing through it. ”

“ The things that are done with wire in the Western Electric factories are too many for any mere outsider to remember. Some wire is wrapped with paper tape at a speed of nine thousand miles a day. Some is fashioned into fantastic shapes that look like absurd sea-monsters, but which in reality are only the nerve systems of switchboards. ”

“ This is then not a continuous current like we obtained from the chemical battery, but an alternating one, and you will see later on how it can be made to produce similar effects. The oftener the wire passes the magnet the more electricity is generated, so that if we make a coil of the wire and move a large number of parts of wire past at one time, the effects on each part are accumulated ”

“ Iron seems to be the most desirable material for guard wires because it gives the required mechanical strength and sufficient conductivity at a less cost than copper, aluminum, or bronze, and is easier to handle and less liable to break than steel. It was formerly the practice to staple guard wires to the tops of poles or to the ends of cross-arms, but it was found that the wire was more apt to rust and break at the staple than elsewhere, and in the better class of work such wires are now mounted on small insulators. ”

“ To produce the effects by which the messages are expressed at the end of a telegraphic wire or cable, it is necessary that the electric current should have a certain intensity or strength. Now the intensity of the current transmitted by a given voltaic battery along a given line of wire will decrease, other things being the same, in the same proportion as the length of the wire increases. Thus, if the wire be continued for ten miles, the current will have twice the intensity which it would have, if the wire had been extended to a distance of twenty miles. ”

“ If the wiring is situated where contact with electric light wires is possible, heavily insulated wires, such as are prescribed by local regulations, should be used. All permanent wire joints and splices should be snugly twisted a length of 2 inches—or, better, soldered—and wrapped with tape. All outside wires should be held by insulators. ”

“ When they pass along a damp wall, it is best to fix a board and loosely staple them. In no case allow more than one wire to lie under the same staple, and do not let the staples touch one another. In many cases, electric bells have been an incessant annoyance and complete failure, through driving the staples tight up to the wires, and several wires to the same staple,—this must not be done on any account. A number of wires may be twisted into a cable, and run through a short piece of gutta-percha tube, and fastened with ordinary gas hooks where it is an advantage to do so. ”

“ Although the balancer set may be manufactured for more than one intermediate voltage, the General Electric Company recommends the three wire system as it is simpler. The motors may be more equally divided and the reserve margin of the motor is more conservative for that class of work requiring increase in torque with decrease in speed. The voltage of the system being given, the capacity of a three wire balancer set is fixed by the maximum current the neutral wire is required to carry. ”

“ In some of the newer cables wires covered with cotton soaked in paraffine are used instead of gutta-percha-covered wires. The distances within this city are so short that neither induction nor retardation has to be considered in the telegraph wires. Electric-lighting wires, we have seen, are not affected. The telephone wires are in Paris protected from these evils by an extremely simple though expensive device. Instead of a single wire for each circuit, two wires twisted together are used, the current going out over one and returning over the other. ”