Copper wire

“ Therefore the advantages in point of price of iron wire over copper in the first place, would be greatly overbalanced by the increased cost of insulating and sheathing it. It is of the greatest importance that the copper wire of the cable should be as pure as possible, for the slightest trace of arsenic or other foreign element is sufficient to hamper, in some mysterious way, the swift course of the subtle current, and very materially to weaken the conducting power of the wire. ”

“ The Material and Dimensions of the Conductor. The use of copper is almost universal, but two manufacturers occasionally use iron. The form varies. The majority use wire rope, but some use rods, others bands or tapes, others tubes. One firm uses a cable “constructed of 49 strands of hard-drawn square copper wire.” Another firm uses a wire rope, simply because “it appears to be an open question, at present, whether it is surface or mass which conducts.” ”

“ From the standpoint of cross-sectional area aluminum is inferior to copper as an electrical conductor. Comparing wires of equal sizes and lengths, the aluminum have only sixty per cent of the conductivity of the copper, so that an aluminum wire must have 1.66 times the sectional area of a copper wire of the same length in order to offer an equal electrical resistance. As round wires vary in sectional areas with the squares of their diameters, an aluminum wire must have a diameter 1.28 times that of a copper wire of equal length in order to offer the same conductivity. ”

“ Hard drawn copper wire is used in outside construction, because its tensile strength ranges from 60,000 to 70,000 pounds or about twice that of soft copper. This is desirable to withstand the stresses to which the wire is subjected which, in the case of long spans, are considerable.
The table on the next page gives the tensile strength, in pounds per square inch of cross section, hard drawn copper wire of various sizes B. & S. gauge. 800
The metal aluminum possesses certain advantages as a material for overhead wires. ”

“ Yet it required ten years of costly experience with iron wire circuits before the telephone interests fully comprehended the inestimable value of this improvement. In September, 1880, at a conference of telephone men, the representative of a very large wire-drawing mill stated that "copper wire has ceased to be discussed for telephone line use. It is too soft and elongates too readily under exposure. The suitable wire must be tough pure iron, well manipulated to secure flexibility and toughness." ”

“ Not being so apt to tarnish and rust as copper, and being, in other respects, better adapted for the purpose than that metal, it is much used for clock-work, and for mathematical and astronomical instruments. It is more ductile than either copper or iron, and hence is peculiarly fitted to be made into wire, for the strings of musical instruments, and other purposes. Sieves are woven with brass wire, after the manner of cambric weaving, and of such extreme fineness that similar ones could not possibly be made with copper wire. Brass wire, flatted and gilded, is sometimes made into lace. ”

“ The rapid entrance and exit of the steel magnet in the helix of copper wire would be insufficient to produce any quantity of electricity, and the ingenuity of man has been taxed to arrange a method by which a magnet may be suddenly formed and destroyed inside a coil of insulated copper wire. The difficulty, however, has been surmounted by several ingenious contrivances, based on the principles first discovered by Faraday; and the one especially to be noticed is the revolution of a coil of copper wire enclosing a piece of soft iron, called the armature, before the poles of a powerful magnet. ”

“ Its flexibility is such as to make it as manageable as a small line, and its strength such that it will bear, in water, over six miles of its own weight suspended vertically.' The conducting medium consists not of one single straight copper-wire, but of seven wires of copper of the best quality, twisted round each other spirally, and capable of undergoing great tension without injury. ”

“ Even the best description of copper wire can seldom be relied upon for equality of strength throughout, and in some instances an inch or even a less portion of the wire will prove to be slightly crystallised, and consequently incapable of resisting the effects of coiling or paying out if brought to bear upon the part, though no external difference be at all apparent between the weak portion and the remainder of the sample. ”

“ COATING AND FINISHING Use determines much in the finishing of wire, and of wire rope as well, as not alone concerning the chemistry of the inside, but the covering of the outside. Material that is made for service out of doors, under water or under ground, to ensure long life needs an exposed surface more resistant to moisture than the naked steel. Copper is proof, but the pure wire is expensive for most uses and where severe strains are incurred it lacks in strength. Modern science has been too busy to recover the art of hardening copper which the ancient Egyptians lost. ”

“ Twist the ends of the copper wire about the ends of the hairpins (Fig. 134) , and then fasten the hairpins to the block. They may be held firmly by small nails which should be driven partly into the block and bent over. The hairpins at the right-hand side of the Fig. are shown to be near but not touching each other. This allows all to be heated at the same time.
The tin binding-posts may be nailed or screwed to the block, and if the bare copper wires 1 and 4 be placed under X and Y before they are screwed down they will be electrically connected. ”

“ To shew that the copper wire too keeps continuous from ship to shore, a pulse of electricity is sent along the cable at stated intervals, usually every five minutes. This is either sent from the ship to the cable-hut, or from the cable-hut to the ship by the electricians left on duty there. The resistance too of the copper conductor is regularly taken at times, to see whether the conductor remains intact; for the pulse test only shews that it is continuous, and would not shew, for instance, that it had been half broken through. ”

“ Since copper wire stretches easily and becomes loose on the wooden base, it is better to use phosphor bronze wire of about the same size, if the surface covered by the interrupted circuit is more than three or four inches in width. The phosphor bronze wire is more difficult to wind satisfactorily, for it is harder to bend than the copper wire, and it has the further disadvantage of being more brittle. ”

“ Thomson about 1856, viz., that some kinds of copper wire were no better than iron for the purpose of conductivity, and that it required carefully-selected copper to give the desired standard, which may be represented by a copper wire one-tenth of an inch in diameter, being equal to an iron wire one-third of an inch in diameter for electrical purposes. ”

“ Wires of this description, either with or without the tarred tape covering, may be obtained from all the leading electricians' sundriesmen. Many firms use copper wire tinned previous to being insulated. This tinning serves two good purposes, 1st, the copper wire does not verdigris so easily; 2ndly, it is more easily soldered. On the other hand, a tinned wire is always a little harder, and presents a little higher resistance. ”

“ All metals are conductors, but they are not all equally good conductors. Mercury is not so good a conductor as iron, iron is not so good as copper, and silver is still a slightly better conductor than copper. The difference between the two last-named metals is, however, not great enough to justify commercially the use of silver instead of copper wire in the construction of electrical machinery. For the present we need not inquire further into any fine gradations between conductors and insulators. ”

“ Six lengths of five feet each, soldered at ends to piece of copper plate so as form terminations, and these amalgamated. When this bundle was used to connect the electro-motor it gave but very feeble spark on breaking contact, but the spark was sensibly better when the wires are held together so as to act laterally than when they were opened out from each other, thus showing lateral action.
Made a larger bundle of the same fine copper wire. There were 20 lengths of 18 feet 2 inches each and the thick terminal pieces of copper wire 6 inches long and 1⁄3 of inch thick. ”

“ The copper wire, though under ordinary circumstances incapable of being rendered magnetic, thus becomes endowed with strong magnetic properties when it is transmitting an electric current, and acts on the magnetic needle in the same manner as if there were an immense number of small magnets placed along the wire across its diameter. ”

“ This is the meaning of the coils of copper wire around iron cores in the dynamo, in electric bells, in telegraph sounders, in motors, etc., etc. To prevent the electric current from taking the shortest route, through the iron core or through the successive layers of copper wire, the iron core and the wire must be covered with something like wood or paper or cotton or silk or rubber—such things as electricity does not readily pass through—that is, insulating material. ”

“ Copper should be used for several reasons; first, because electricity travels through a copper wire more easily than through iron, and second, for the reason that copper is more ductile than iron, and can be drawn into a wire with greater facility. ”

“ Copper is usually the only metal used to form the wire or conductor itself. The reason for this is that copper is a better conductor than any other metal except those known as precious metals, such as gold and silver, the cost of which prohibits their use for such purposes. The wire may be solid, or made up of a number of small conductors so that it is flexible. ”

“ The copper wire may be built into the wall to prevent theft, but should be connected to any outside metal, such as lead or zinc on the roof, and to metal rain-water pipes. In the case of a powder-mill it might be advisable to make the network closer by carrying one or two additional wires over the roof and down the walls to the wire at the foundation. ”

“ The piles of this equipment, waiting shipment in the Roebling storerooms, give proof that the satire of the cartoonist and the mockery of the funny writer cannot destroy an ancient faith.
The telephone and telegraph companies use uncountable miles of copper wire in line service and other miles in fine sizes for instrument coils and divers other functions. Electricity as an agent would be a halting cripple without wire. The dynamo would have little more utility than a washtub. Armatures, frames for which are formed from flat steel wire, are wound in the Roebling plant in impressive number. ”

“ The electric current entering the copper coil at one end is confined from leaving the copper wire by any lateral path: it must circulate around each and every convolution, nor be permitted to flow back by the return-wire until it has performed the required amount of circulation. That the mere external circulation of electric current around a totally disconnected interior core of iron should magnetise that core; that the magnetisation should be maintained so long as the circulation of electricity is maintained ”

“ While copper wire of commerce is not absolutely pure, the requirements for its use as a conductor of electricity are such that the impurities constitute only a few hundredths of one per cent and are negligible for analytical purposes. ”

“ It cases wire in asbestos to prevent fire from stopping its work; but perhaps the highest phase is reached in the great cables of copper wires used in telephone service. For these the individual wires are covered with paper of various colors, which serves not only for protection but enables men at the opposite ends of a long cable to pick out unerringly the wires with which connection is to be made. Colors are few but possible combinations are many. ”

“ A triple coating of gutta percha, to keep the sea from sucking out the electricity, and a thick coating of iron wire, to sink the cable to the bottom and give it strength, were added to the copper rope, and then the cable was complete. No less than 325,000 miles of iron and copper wire were woven into this great cable,—as much as might be wound thirteen times round the globe ”

“ A short distance below the carbon are the two terminals of the electric circuit which, when completed by the lowering of the carbon, gives the alarm. Now if there be a very gradual change of temperature the steel rod lengthens slowly, and so does the copper wire, so that the amount of sag remains practically what it was before. But in event of a fire the copper expands much more quickly than the steel, and sags until the carbon completes the circuit. ”

“ For most of the work from 18 to 24 gauge is used, while metal from 12 to 18 gauge is used occasionally.
Copper wire is used in several sizes for making rivets.
No. 22 and 28 iron wire is indispensable for binding when soldering.
Easy running silver solder may be made by the user, but as a small piece will solder many joints, and as it is not practical to make it in small quantities, it is better to buy it ready made as desired.
Powdered or lump borax is used as a flux in soldering. Charcoal or asbestos blocks are used when soldering small work. ”