The insurance code—Different kinds of wiring described—Wooden moulding cheap and effective—The distributing panel—Branch circuits—Protecting the circuits—The use of porcelain tubes and other insulating devices—Putting up chandeliers and wall brackets—"Multiple" connections—How to connect a wall switch—Special wiring required for heat and power circuits—Knob and cleat wiring, its advantages a
The task of wiring your house is a simple one, with well-defined rules prescribed by your insurance company. Electricity, properly installed, is much safer than oil lamps—so much so indeed that insurance companies are ready to quote especial rates. But they require that the wiring be done in accordance with rules laid down by their experts, who form a powerful organization known as the National Board of Fire Underwriters. Ask your insurance agent for a copy of the code rules.
Danger of fire from an electric current comes from the "short circuit," partial or complete; and it is against this danger that the rules guard one. The amount of electricity flowing through a short circuit is limited only by the fuse protecting that line; and since there is no substance known that can withstand the heat of the electric arc, short circuits must be guarded against. Happily the current is so easily controlled that the fire hazard is eliminated entirely—something which cannot be done with oil lamps.
In house-wiring for farm plants, the wire should be rubber-covered, and not smaller than No. 14 B. & S. gauge. This is the wire to use on all lamp circuits. It costs about $0.85 cents per 100 feet. There are four kinds of wiring permitted, under the insurance code:
(1) Flexible armoured cable: This consists of two-wire cable, protected with a covering of flexible steel. It is installed out of sight between the walls, and provides suitable outlets for lamps, etc., by means of metal boxes set flush with the plaster. It is easily installed in a house being built, but requires much tearing down of plaster for an old house. Since its expense prohibits it in the average farm house, this system will not be described in detail here.
(2) Rigid and flexible conduit: As the name implies this system consists of iron pipe, in connection with flexible conduit, run between the walls. It differs from the above system, in that the pipes with their fittings and outlet boxes are installed first, and the wires are then "fished" through them. Duplex wires—the two wires of the circuit woven in one braid—are used; and a liberal amount of soapstone, and occasionally kerosene, are used to make the wires slip easily into place. This is the most expensive system, and the best; but it is difficult to install it in an old house without tearing down a good deal of plaster. It has the advantage of being absolutely waterproof and fireproof.
(3) Wooden moulding: This is simply moulding, providing two raceways for the insulated wires to run in, and covered with a capping. It is nailed or screwed firmly to the wall, on top of the plaster; and when the wires have been installed in their respective slots and the capping tacked on, the moulding is given a coat of paint to make it in harmony with the other moulding in the room. This system is cheap, safe, and easily installed, and will be described in detail here.
(4) Open wiring: In open wiring, the wires are stretched from one support to another (such as beams) and held by means of porcelain cleats, or knobs. It is the simplest to install; but it has the objection of leaving the wires unprotected, and is ugly. It is very satisfactory in barns or out-buildings however.
The Distributing Panel
The first point to consider in wiring a house with wooden moulding is the distribution board. It should be located centrally, on the wall near the ceiling, so as to be out of ordinary reach. It consists of a panel of wood—though fireproof material is better—firmly screwed to the wall, and containing in a row, the porcelain cut-outs, as shown in the cut, from which the various branch circuits are to be led. Each cut-out provides for two branch circuits; and each branch contains receptacles for two plug fuses. These fuses should be of 6 amperes each. The Insurance Code limits the amount of electricity that may be drawn on any branch lamp circuit to 660 watts; and these fuses protect the circuit from drafts beyond this amount.
The mains, leading from the entrance switch, as shown in the diagram, to the panel board, should be of the same size as the transmission wire itself, and rubber-covered. These mains terminate at the distributing board. They are connected to the terminals of the cut-outs by means of heavy brass screws.
The branch circuits are, as has been said, of No. 14 rubber-covered wire, running concealed in wooden moulding. All joints or splices in this wire are made, as shown in the illustration, by first scraping the wires bright, and fastening them stoutly together. This joint is then soldered, to make the connection electrically perfect. Soft solder is used, with ordinary soldering salts. There are several compounds on the market, consisting of soft solder in powder form, ready-mixed with flux. Coat the wire joint with this paste and apply the flame of an alcohol lamp. The soldered joint is then covered with rubber tape, and over this ordinary friction tape is wound on. A neat joint should not be larger than the diameter of the wire before insulation is removed.
First, make a diagram of your rooms and indicate where you wish lamps, or outlets for other purposes. Since wooden moulding can be run across ceilings, and up or down walls, lamps may be located in places where they are out of the way. In planning the circuit, remember that you will want many outlets in handy places on the walls, from which portable cords will convey current to table lamps, to electric irons and toasters and other handy devices which can be used on the lamp circuit. These outlets are made of porcelain, in two pieces. One piece is merely a continuation of the moulding itself; and the other is a cap to connect permanently to the end of the lamp or iron cord, which may be snapped into place in a second. Since there are a great many designs of separable current taps on the market, it is well to select one design and stick to it throughout the house, so that any device can be connected to any outlet.
The code permits 660 watts on each circuit. This would allow 12 lamps of 55 watts each. It is well to limit any one circuit to 6 lamps; this will give leeway for the use of small stoves, irons, toasters, etc. without overloading the circuit and causing a fuse to blow.
Having installed your distributing board, with its cut-outs, figure out the course of your first branch circuit. Let us say it will provide lights and outlets for the dining room and living room. It will be necessary to run the wires through the partitions or floors in several places. For this purpose porcelain tubes should be used, costing one to three cents each. Knock holes in the plaster at the determined point, insert the tubes so they project ¾ inch on each side, and fill up the ragged edge of the hole neatly with plaster.
When all the tubes have been set in place, begin laying the moulding. Run it in a straight line, on the wall against the ceiling wherever possible, mitering the joints neatly. Whenever it is necessary to change the run from the ceiling to the wall and a miter cannot be made, the wires should be protected in passing from one slot to the other by being enclosed in non-metallic flexible conduit, called circular loom.
In running wooden moulding, avoid brick walls liable to sweat or draw dampness; keep away from places where the heat of a stove might destroy the rubber insulation of the wires; do not pass nearer than six inches to water pipes when possible—and when it is necessary to pass nearer than this, the wooden moulding should pass above the pipe, not below it, with at least an inch of air space intervening, thus avoiding dampness from sweating of pipes.
Places where chandeliers or wall bracket lamps are to be installed permanently are fitted with wooden terminal blocks, which fit over the moulding and flush with the plaster. These, after holes have been bored in them for the wires, and the wires drawn through, should be screwed firmly to the wall or ceiling, always choosing a joist or beam for support. Then a crow's-foot, or tripod of iron, tapped and threaded for iron pipe, is screwed to the terminal block. The iron pipe of the chandelier or wall bracket is then screwed home in this crow's-foot.
Do not begin stringing wires until all the moulding of the circuit has been laid. Then thread the wires through the wall or floor tubes and lay them in their respective slots. If trouble be found making them stay in place before the capping is put on, small tacks may be driven into the moulding beside them to hold them. When a terminal block is reached, a loop is made of each wire, through the hole cut in the block, if the circuit is to continue in the same direction. If it is to end there, the two wires are drawn through taut, and cut off at a length of 5 or 6 inches. These end wires, or loops, are then scraped bare and spliced to the two wires coming out of the chandelier or wall bracket. This joint is then soldered and covered with tape, and the shell of the chandelier is screwed into place, covering the joint.
If the moulding is run along the walls flush with the ceiling, as is usual, a branch is made for a wall light, or wall tap, by means of a porcelain "T," or branch-block, which provides the means for running the circuit at right angles to itself without letting the wires come in contact with each other where they cross. Separable current taps should be installed in handy places on all circuits, so that small heating devices may be used without removing the lamps from their sockets. The two wires are bared for half an inch where they run through these current taps, and are fastened by means of brass screws.
All electric devices for this installation—lamps, irons, vacuum cleaners, motors—must be connected across the circuit—that is, bridged, from one wire to the other. This is called multiple, or shunt connection. There is only one exception to it, in wiring the house. That one exception is installing a wall switch, the ordinary snap switch. Since this wall switch, is, in effect, merely an instrument, which opens or closes a circuit, it should be connected to only one wire, which is cut to provide two ends for the screw connections in the switch. When a moulding branch is run down from the ceiling to some convenient spot for a snap switch (with which to turn the lights of a room on or off), a porcelain "T" is not used. All that is necessary to do is to loop the bottom wire of the circuit down through the branch moulding, and connect it to the switch at a terminal block, or porcelain base.
In wiring lamp fixtures, No. 14 rubber-covered wire will usually prove too large. For this purpose, No. 18 may be used, with one lamp to each loop. Hanging lamps may not be supported by electric lamp cord itself, if there is more than one lamp in the cluster, because the weight is apt to break the electrical connections. In such a case, the lamp should be supported by a chain, and the twisted cord conveying current to the electric bulbs, is woven in the links of the chain. For the pantry, kitchen, woodshed, barn, etc., a single hanging lamp may be suspended from a fielding rosette, as shown in the cut, provided a single knot is tied inside both the rosette and the lamp socket, to make it secure. This makes a very cheap fixture. The rosette of porcelain will cost 15 cents; the lamp socket 20 cents, and the lamp cord suspending the lamp and carrying the current will cost 1½ cents a foot; while a tin shade will cost another 15 cents.
In all communities, your insurance agent must inspect and pass your wiring before you are permitted to throw the main switch and turn on the electricity. Frequently they require that the moulding be left uncapped, until they have inspected it. If you have more than 660 watts in lamps to a circuit; if your joints are not soldered and well taped; if the moulding is used in any concealed or damp place, the agent is liable to condemn your work and refuse permission to turn on the electricity. However the rules are so clearly defined that it is difficult to go wrong; and a farmer who does his own wiring and takes pride in its appearance is more apt to be right than a professional electrician who is careless at his task. After the work has been passed, tack on the moulding capping, with brads, and paint the moulding to match the woodwork.
Wooden moulding wiring is perfectly satisfactory if properly installed. It is forbidden in many large cities, because of the liability of careless workmanship. It should never be installed in damp places, or out of sight. If the work is well done, the system leaves nothing to be desired; and it has the additional advantage of being cheap, and easily done by any farmer who can use carpenter tools. Farmers with moulding machinery can make their own moulding. The code prescribes it shall be of straight-grained wood; that the raceways for the wires shall be separated by a tongue of wood one-half inch wide; and that the backing shall be at least 3/8 inch thick. It must be covered, inside and out, with at least two coats of moisture-repellant paint. It can be had ready-made for about 2 cents a foot.
Special Heating Circuits
If one plans using electricity for heavy-duty stoves, such as ranges and radiators, it is necessary to install a separate heating circuit. This is the best procedure in any event, even when the devices are all small and suited to lamp circuits. The wire used can be determined by referring to the table for carrying capacity, under the column headed "rubber-covered." A stove or range drawing 40 amperes, would require a No. 4 wire, in moulding. A good plan is to run the heating circuit through the basement, attaching it to the rafters by means of porcelain knobs. Branches can then be run up through the floor to places where outlets are desired. Such a branch circuit should carry fuses suitable to the allowed carrying capacity of the wire.
Knob and Cleat Wiring
Knob and cleat wiring, such as is used extensively for barns and out-buildings, requires little explanation. The wires should not be closer than 2½ inches in open places, and a wider space is better. The wires should be drawn taut, and supported by cleats or knobs at least every four feet. In case of branch circuits, one wire must be protected from the other it passes by means of a porcelain tube. It should never be used in damp places, and should be kept clear of dust and litter, and protected from abrasion.
Knob and tube wiring is frequently used in houses, being concealed between walls or flooring. In this case, the separate wires are stretched on adjoining beams or rafters, and porcelain tubes are used, in passing through cross beams. For a ceiling or wall outlet, a spliced branch is passed through the plaster by means of porcelain tubes or flexible loom.
Wires from the house to the barn should be uniform with transmission wires. At the point of entry to buildings they must be at least six inches apart, and must take the form of the "drop loop" as shown in the illustration. A double-pole entrance switch must be provided, opening downward, with a double-pole fuse. In passing over buildings wires must not come closer than 7 feet to flat roofs, or one foot to a ridge roof. Feed-wires for electric motors should be determined from the table of safe carrying capacities, and should be of liberal size.