Wire mesh

“ 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. ”

“ As shown in fig. 638, a wire AX, of non-oxidizable metal, of high resistance and low temperature coefficient, passes over a pulley B mounted on the shaft C. The ends of the wire are attached to the plate E at its ends F and G, the wire being insulated from the plate at G. A spring H holds the wire in tension and takes up the slack due to the expansion caused by the heating of the wire when a current passes through it. ”

“ Who has not seen men in the streets dragging huge pipes of lead through the open manholes from big wooden spools? These are the cables you talk over. They have been papered and clothed—and tarred and feathered, maybe—and then encased in lead by a process that is so easy as to be laughable, and yet as ingenious as any one thing the wire miller does. Unrolling slowly from its spool, the heavy cable moves up to a machine built strong and four-legged from the floor. ”

“ No joint can possibly be perfect that is not metallically continuous. Careful soldering is the only certain mode of securing this, and that this is practicable is evident from the millions of perfect joints in telegraph wires. To scrape the ends of wire bright, and cover the whole with thin sheet lead, as is done by one firm, is simply to court danger. The absence of joints in wire rope is one great element in its favour.
(21) 5. Attachment to building, how made. Some attach the conductor to the building by copper straps and nails; some use holdfasts, either of copper wire or gun metal ”

“ FIG. 24.—Showing how wires are arranged and insulated.
Aluminum wire is very light, and causes very little strain on the pole or cross-arms. It offers more resistance than copper, but some of the larger sizes may be used with equally good results.
Iron wire must never be used, even if galvanized or tinned. It possesses a certain reactance tending to choke off the high frequency currents.
FIG. 25.—Aerial insulator. ”

“ In splicing wire, great care should be taken to prevent kinks getting in the rope or strands.
With steel wire, always before working it, put a stop on at the place to which you intend to unlay, and also put a good whipping of twine at the end of each strand.
Steel wire is six-stranded right-handed, and has a heart of hemp. Flexible wire has a heart of hemp in each strand. ”

“ 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. ”

“ As the material for wire gauze and cloth, wire rope, cable, piano strings, springs of all sorts, pins, needles, nails, fence, barbed wire, and the myriad of other things, wire really is one of our great products.
It was mentioned that piano wire had been made which had a tensile strength as high as 400,000 pounds per square inch, which is six or seven times the strength of an equivalent cross-section of steel rail or plate. Wire is undoubtedly the strongest product which is made from steel. This is why wire rope or cable is so strong. ”

“ 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. ”

“ In the making of wire screens the wire men have taken a leaf from the cloth-mill book, but in weaving a casing of cotton or other fibre around the wire for insulation the process is strongly reminiscent of some of the New England textile mills. Long rows of machines, black and silent and swift, reaching upward toward the ceiling, revolving rapidly on an upright shaft; long arms trailing downward, with wheels and bobbins like fingers plying dizzily but swiftly in and out around the wire which unwinds from its spool and keeps forever climbing. ”

“ 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. ”

“ No thinkable effort is omitted that will help to make the wire material perfect in quality and service condition, but the proof of the pudding in the making of wire is in the Olsen machines—miraculous things that will smash a big wire rope or snap a hair of wire and register to a decimal the breaking strength of each. There are tests for tensile strength, for torsion to show how many twists a piece of wire will stand, and for bending. ”

“ The joints connecting these rubber covered wires and the cable conductors are spliced in the same manner as straight splices, the paper sleeves used being of sufficient diameter to be backed out of the way over the rubber insulation. When the splice is completed a brass shell threaded at one end to fit a female thread in the upper end of the brass base, is slipped over the end of the rubber covered wire and screwed into the base. ”

“ It is well to have 1⁄2 lb. of No. 24 or 25 for electro-magnets, current-detectors, etc., etc. 1⁄2 lb. of No. 30 will not be too much, if you make induction coils. If you handle your wire carefully, single cotton-covered will do. Double cotton-covered is better than single, but it costs more. Be careful not to injure the covering. (See below for splicing wire.) Look out for broken wire.
288. Splicing Wire. Fig. 125. Do not simply touch [Pg 140] two wires together and imagine that you have a good connection; a mere twist is not sufficient. ”

“ Insulate every joint, and don’t leave loose joints; they consume too much current.
Don’t cross wires that are insulated without bushing the overlying wires, and never cross uncovered wires.
123Don’t bring a wire through the floor or back of window without using clay bushings; that’s what they are for.
Don’t run wires (as in Fig. 8) without using a lamp, or cutting wires where X is marked; it saves a short circuit.
Don’t let the wires to your lamps touch brass, except under the screw.
Don’t attempt to connect your design to your “cut-out” until you are sure your switch is open. ”

“ In the production of very fine wire, the metal, after passing a few times through the draw-plate, requires annealing, as its fibres become so condensed and hardened that it is impossible to repeat the operation without some risk of the wire breaking. ”

“ In this respect the best material for fuse wires is silver. An exceedingly thin silver wire will carry a fairly large current, and if the current should rise to a dangerous value and the wire be fused, the amount of material volatilised is so small that there is hardly any explosive effect, especially if the wire is embedded in carborundum powder. ”

“ At the left, the bare lugs are shown; in the center the copper of the conductors is shown inserted into the lugs, and at the right the whole conductor is shown bent back, the metal of the lug catching over the insulation to keep it from fraying out. The wires feeding arc lamps are always asbestos covered and this covering fits loosely to the wire and must be held in some such manner. A stock of such lugs should always be carried, as the leading-in wires to arc lamps, using heavy currents, frequently burn off. ”

“ If the pins and cross-arm are entirely of iron, the total resistance of the path through them from wire to wire is practically that of the insulator surfaces. If the pins and cross-arm are of wood which is dry, they may offer an appreciable part of the total resistance of the path through them between the wires of a circuit; but if the wood be wet, its resistance is very much reduced. ”

“ Outside wire, when run along walls and exposed to the weather, should be covered with rubber and compound, and varnished or tarred on an outer covering of tape or braid. Hooks or staples must be well galvanised to prevent [Pg 158] rusting, and fixed loosely. If the wire is contained within an iron pipe, a lighter insulation may be used: but the pipe must be watertight. In a new building, wires must be contained within zinc or copper bell tubes. A 3⁄8 inch tube will hold two wires comfortably. ”

“ Before me on the table is a spiral of copper wire, and in this wire, by special means, I can create what we call an electric current. I shall ask you to notice that when this is done two effects are immediately produced. In the first place, the wire becomes hot, and, secondly, it becomes magnetic. The fact that it is hot is evident, because it is now nearly red hot, and is visibly incandescent in the dark. If we dip the wire in iron filings, you will see that these cling to the wire and are taken up by it, just as when an ordinary steel magnet is substituted for the wire. ”

“ Where poles have heavy circuits and several cross-arms each it is sometimes desirable to attach a guy or strut beneath the lowest arm and also a guy close to the pole top. Galvanized iron or steel wire is the material best suited for guys, and the cable form has greater strength and is more flexible than solid wire. ”

“ The wire must then be carefully covered with warm Prout's elastic or softened gutta-percha, heated and kneaded round the wire with the fingers (moistened so as not to stick) until the joint is of the same size as the rest of the covered wire. As a further precaution, the joints should be wrapped with a layer of tarred tape. Let me strongly dissuade [Pg 149] the fitter from ever being contented with a simply twisted joint. Although this may and does act while the surfaces are still clean, yet the copper soon oxidises, and a poor non-conducting joint is the final result. ”

“ Binding-Post. Fig. 28. Two copper or tin strips fastened at one end by a screw, the upper strip being bent a little at one end, make a connector that is useful for some purposes, where you want to make and break the connection frequently. The bare end of the wire which belongs to the apparatus is fastened under the screw-head. The outside wire, or wires, to be connected are pushed between the strips of metal. Another way is to fasten the outside wire to a strip of metal about 1⁄2 in. ”

“ Each of these wires was boiled three several times in linseed oil, giving it an oleaginous coating of considerable thickness and great adhesive power. Each wire was carried across the river separately, from tower to tower, by a contrivance of the engineers, the chief feature of which was a light iron pulley about twenty inches in diameter, suspended on what might be called a wire cord. ”

“ Where wires are too large to be twisted together, the ends are given a short bend and the two wires wrapped firmly together with a smaller bare copper wire, after which the joint is thoroughly tinned and soldered, preferably by pouring hot solder over the joint. The joint is then insulated by wrapping it with two layers of pure rubber, and three layers of tape, sufficient to make the insulation thickness equal to that of the wire, after which the whole joint should be painted with water proof paint. ”

“ Another advantage of high tension is the small effect of line resistance upon the current, a consequence of which is that mines may be fired at long distances from the machine, and through iron wire of very small section. A disadvantage of high tension is the necessity for a perfect insulation of the wires.
When electricity of low tension is employed, the [50] insulation of the wires needs not to be perfect, so that leakages arising from injury to the coating of the wire are not of great importance. In many cases, bare wires may be used. ”

“ The physical properties requisite to make useful wire are possessed by only a limited number of metals and metallic alloys. The metals must in the first place be ductile; and, further, the wire when drawn out must possess a certain amount of tenacity, the quality on which the utility of wire principally depends. The metals suitable for wire, possessing almost equal ductility, are platinum, silver, iron, copper, aluminium and gold ”

“ Rubber insulated copper wire covered with a double braid should preferably be used, and the duplex wire is often more convenient than the single wire, especially in running from one building to another. Wiring on the inside of buildings should be done neatly, running the wires on porcelain insulators, and as directly to the appliance as possible. ”

“ In carrying this discovery into practice in making dynamo-machines we use copper wire. If iron were used, there would be a current of electricity generated, but it would be much less in quantity, because iron wire [59] has much greater resistance to the passage of electricity than the same size of copper wire.
Perhaps you can understand it more thoroughly if we state that when a closed loop of wire is passed up and down between the poles of a strong magnet there is a very perceptible opposition felt to the passage of the wire to and fro. ”