The dynamo is mounted on a firm floor foundation; and it is belted from the countershaft by an endless belt running diagonally. A horizontal belt drive is the best. Vertical drive should be avoided wherever possible.
The Switchboard
The switchboard originally consisted of a wooden frame on which were screwed ordinary asbestos shingles, and the instruments were mounted on these. Later, a sheet of electric insulating fibre was substituted, for look's sake. The main requisite is something substantial—and fireproof. The switchboard instruments consist of a voltmeter, with a range of from 0 to 150 volts; an ammeter, with a range, 0 to 75 amperes; a field regulating rheostat (which came with the dynamo); a main switch, with cartridge fuses protecting the machine against a draft of current over 60 amperes; and two line switches for the two owners, one fuse at 20 amperes, and the other at 40 amperes. Electric fuses are either cartridges or plugs, enclosing lead wire of a size corresponding to their rating. All the current of the line they protect passes through this lead wire. If the current drawn exceeds the capacity of the lead wire, it melts from the heat, and thus opens the circuit, and cuts off the current.
Items of Cost
This water wheel would cost $250 new. There is a duplicate in the neighborhood bought at second-hand, for $125. The dynamo cost $90, and was picked up second-hand in New York City. New it would cost $150. The voltmeter cost $7, and the ammeter $10; and the switches and fuses could be had for $5. A wheel one-half the size, using one-half the amount of water at full gate, would do the work required, and the cost would be correspondingly less.
Capacity
This plant supplies two farms with electric light. One farm (that of the owner of the wheel) has 30 lamps, of 16 candlepower each, and two barn-yard lamps of 92 candlepower each. His wife has an electric iron and an electric water heater. Needless to say, all these lamps, and the iron and water heater are not in use at one time.
Carbon Lamps Gem Type (¼ scale)
The partner who owns the electric part of the plant has 30 lamps in his house and barn, many of them being 25 watt tungsten, which give more light for less power, but cost more to buy. They are not all in use at one time, though (since the current costs nothing) the inclination is to turn them on at night and let them burn. In his kitchen he has an electric range, and a water heater for the 40 gallon boiler. In addition to this he has all sorts of appliances,—irons, toasters, grills, a vacuum cleaner, a vibrator, etc. Naturally all these appliances are not in use at one time, else the draft on the plant would be such as to "blow" the fuses. For instance, all the baking is done in daylight; and when the oven is used after dark, they are careful to turn off all lights not needed. An ideal plant, of course, would be a plant big enough to take care of the sum of lamps and handy devices used at one time.