N. Hawkins

“ All conduits should be made continuous from one junction or outlet box to another, or to the various fixtures. A conduit installation is made a complete system by the use of outlets, outlet boxes, switch or junction boxes, and panel boxes with doors and locks, which serve to thoroughly protect the circuit at all points.
Figs. 898 to 901.—Pull boxes and their use in conduit work. A pull box is a convenient device used for the purpose of avoiding the disadvantages of having too many bends in one continuous line of conduit; too many bends will give trouble when the conductors are drawn in. ”

“ If the resistance of A be equal to that of B, there is no pressure in the booster field to establish current through it. The drop through A + B is equal to the total battery voltage, and if A = B, the drop from either side of the battery through A or B is one-half the total drop, hence the end of the booster field winding, connected to the upper ends of A and B is also at the pressure of the middle point of the battery which is likewise the pressure of the other side of the booster field coil. ”

“ If the battery pressure be lower than normal, it will not discharge rapidly enough to relieve the dynamo from overload fluctuations, unless the booster voltage be increased, and the dynamo will therefore have to supply a current greater than normal. If a current greater than normal flow through the compensating coil, the effect of the shunt coil opposed by the series coil is decreased, and the compensating coil, acting in the same direction as the series coil, causes a higher booster pressure tending to discharge the battery, and thus brings down the dynamo load to normal. ”

“ The ground wire should be securely soldered to a brass plug firmly screwed into the pipe, and both strongly stapled to the pole so there will be little danger of the connection being broken.
A good ground is important, as the efficiency of the protection would be impaired if the ground connection were poor. Wherever the earth is dry and a good ground cannot surely be obtained, an excavation 4 or 5 feet deep should be made, and after placing the copper ground plate or iron pipe in the hole, it should be filled with crushed coke or charcoal about pea size. ”

“ 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. ”

“ A dynamotor is a combination of dynamo and motor on the same shaft, one receiving current, usually of different voltage, the motor being employed to drive the dynamo with a pressure either higher or lower than that received at the motor terminals. A machine of the dynamotor form, with its windings exactly alike, is often used in three wire systems to balance or equalize the two halves of the circuit as in fig. 798.
Boosters.—In general, a booster may be defined as a dynamo inserted in series in a circuit, to change its voltage. ”

“ The tree system consists of a feeder reducing in size and supplying mains for each floor, the general arrangement resembling the trunk and branches of a tree. Since fuses must be inserted on each floor where the size of the feeder is reduced, the system requires a large number of joints, and in the event of a fuse blowing it could not be quickly located. The tree system is not to be recommended, as it results in considerable drop, and at full load the lamps nearest the point of supply will either burn too brightly or those more remote will not give the rated candle power. ”

“ If lamps or other devices, designed for that particular current, be connected in series on the secondary circuits, the dynamos D will always maintain that current, no matter how many lamps there may be. When lamps are added, the resistance of the local circuit is raised, and the current in it decreases, so that the dynamo increases its speed until it generates sufficient pressure to produce practically the same current as before. ”

“ Without a voltmeter, the positive terminal of the charging circuit can be determined by attaching a piece of clean lead to each wire which is to be connected to the battery, and immersing them, without touching each other, in a glass or other insulating vessel containing water to which is added a drop or two of sulphuric acid. After the current has passed through the circuit for a short time, the positive lead will commence to discolor, and, if left long enough, will turn brown. ”

“ Fig. 805.—Crocker Wheeler motor-dynamo set. There are numerous cases where such a combination is useful for furnishing a circuit with a voltage different from that of the main plant or with a voltage that can be varied independently. For storage battery charging and electrolytic work, where constant current is desirable, it forms a simple means of voltage regulation. Where a circuit of special voltage is required, the set not only supplies current at the desired pressure, but insulates the special circuit, which may be subject to more severe requirements than the main system. ”

“ A good temperature for the battery room is about 60° F. A damp, dirty room is conductive to grounds and surface leakage, and there is danger of impurities getting into the cells. If the room be very damp the electrolyte may absorb enough moisture to cause the cells to overflow. Strong floors are necessary to support a battery, as one of a 100 ampere, 125 volt capacity weighs from 12 to 13 tons. A wood floor may be used, but a cement floor is better, and a glazed vitrified brick floor is better still. Wooden floors will rot quickly from the acid, which is sure to get onto it more or less ”

“ If the battery can be charged at times when the dynamo is supplying no other load, only one end cell switch is required.
If the load on the external circuit be small, the dynamo voltage rises and current flows into the battery. In this case the series field acts against the shunt field and decreases the booster voltage so that the pressure at the dynamo is greater than booster and battery voltage combined, thus increasing the rate of charge of the battery until the load causes the dynamo voltage to drop to normal and the system is again balanced. ”

“ To remove cable armours, clamp the conductor firmly in the armour cutter and with a pair of cutting pliers back the armour off, one strip at a time, to the point of contact with the cutting edge of the tool. The vise for holding conduit takes all sizes. The conduit can be cut with an ordinary hacksaw. To protect the insulation against any possible injury while the wire is being drawn in, a soft metal bushing should be inserted in the end of the tube and secured permanently thereto by means of the bushing tool. ”

“ No harm results even if the secondary be short circuited, since only the normal current can be generated. But if the secondary circuit be opened, then the machine will race, and probably injure itself by centrifugal force, because the torque of the motor M has its full value, and there is no load upon the dynamos D. To guard against this danger, some automatic device should be provided to short circuit the field or armature of the motor when its speed or reverse voltage rises above a certain point. ”

“ In Canada, reinforced concrete poles are made square on account of the ease of making, and also on account of the steel economy permitted thereby. All poles are made at the point of erection. They are moulded in wooden forms, in a horizontal position, the top side being left open and finished with a trowel. The concrete is composed of one part of 805 Portland cement, two parts clean sharp sand, and four parts broken stone. A 35 foot pole for ordinary line work weighs about 21⁄2 tons and a 50 foot pole about 5 tons. ”

“ The motor is series wound and connected in series with one leg of the feeder. Thus, the voltage which the booster will add to the line will be directly in proportion to the current flowing in the feeder. The regulation is therefore automatic.
When an unbalanced load comes on, the voltage on the lightly loaded side rises and on the heavily loaded side drops. The machine on the light side then takes power from the line and runs as a motor driving the machine on the heavy side as a dynamo, supplying the extra current for that side. ”

“ When the load is below the average, the dynamo charges the battery, and when the load rises above the average, during the hours of maximum demand, the battery discharges into the line in parallel with the dynamo. During the hours of minimum demand the engines may be shut down and the necessary current supplied from the battery alone, thus not only increasing the efficiency of the plant, but serving to maintain a steadier pressure under fluctuating loads. ”

“ Charging.—Before beginning to charge a storage battery, it should be gone over carefully, and any cell that is not up to the standard should be disconnected and put in working order before being replaced. In general, if the current used in charging be too large, it will waste energy by evolving an excess of heat and gas; if too small, an insulating deposit of white lead sulphate will be formed on the positive plate, thereby preventing the formation of the proper amount of lead peroxide. ”

“ The term wiring is commonly understood to mean the methods employed in laying the conductors used for the transmission and distribution of electrical energy for lighting, power, and other purposes. Interior wiring, comprises the various methods of installing the conductors from the entrance devices in the walls or other parts of the buildings to the lamps, motors, and other electrical apparatus within the buildings. ”

“ Another reason is that in changing the size of a wire, the underwriters require a fuse to be inserted. This makes it necessary to install a larger panel with larger trim, etc., and the consequent expense easily offsets any gain made by installing a smaller wire.
In a building covering a large area it is often advisable to install two panels or centers to a floor, with two sets of feeders. It is advisable to keep circuit lengths down to 100 feet or less, and the judicious laying out of circuit centers will save many feet of wiring. ”

“ An ammeter with suitable scale should be inserted in the battery circuit to indicate the current. For charging more than one battery at a time from a 110 volt circuit, the batteries should be connected in series (positive terminal of one battery to the negative of the next, and so on) . The charging rate should be that of the battery with the lowest rate. The resistance to be inserted will be less than if only one battery is being charged; where lamp resistance is used, this means more lamps in parallel. ”

“ It is said that three washings a day are sufficient to prevent all serious danger of poisoning. The benzole in the petroleum appears to scour the skin and remove the loose lead dust, and the fatty substance in the oil fills up the pores of the skin and prevents the absorption of the deleterious salts. The employment of petroleum has given such good results that it has been proposed to use this material as a guard against poisoning in other industries where the salts of copper or mercury are employed. ”

“ It is not necessary for the dynamo to have a capacity exceeding that which is sufficient for the average daily load, at which it may be worked practically all the time.
Fig. 1,180.—Storage battery connected in parallel with a dynamo. This arrangement enables the dynamo to be stopped for a considerable portion of the time, and thus save labor and attention. It also acts to prevent fluctuations as in a dynamo driven by a gas engine whose speed varies periodically because of the nature of its cycle of operation. ”

“ Lead zinc cells are similar to the preceding type, but differ by having zinc for the negative electrode, and zinc sulphate for the electrolyte. The voltage of these cells is slightly higher than that of the ordinary cell, and their capacity per unit of total weight is high, but they are apt to lose their charge on open circuit, besides they possess most of the disadvantages of the Plante cells. ”