The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Practical Electricity And House Wiring
In all motors that are permanently wired, a switch should be used which will disconnect all wires to the motor, so that if repairs or inspection are necessary on the motor, or on the machine that the motor drives, there will be no danger whatever of the motor starting when not expected.
It is best to use one of the modern overload-protection type of controllers of the style shown in Fig. 262. This device consists of two essential parts: a switch to control the motor, and a thermal cutout, which is a device which will carry many times its rated amperage for a short period, long enough for the motor to start, but which will open the circuit if even a small overload continues for a considerable length of time, as when a motor is overloaded, thus protecting the motor. For example, in one popular brand, the thermal cutout in the 10 amp. rating, will carry 10 amp. continuously, 12 amp. 25 minutes, 15 amp. 10 minutes, 20 amp. 1 minute, 25 amp. 25 seconds, 50 amp. 10 seconds, 75 amp. 5 seconds, 100 amp. 2 seconds. When it does trip, it is reset by pushing a button, although it cannot be reset so long as too much current flows, thus doubly protecting your motor, if for example, a careless attendant tried to hold it in the "ON" position despite an overload.
This type of switch is also available with a push-button control so that the motor can be controlled from a distance.
Principles Of Efficient Lighting
In most homes a great portion of the light produced by lamps is wasted. We must recognize of course that our lamps serve not only the purpose of utility but decoration as well, yet at the same time we should take full advantage of what light is produced.
Cost of Light.—The selection of the lamp is important. The cost of light is composed of two factors—the cost of the lamp itself, plus the cost of the current required to operate it. For example, a 40-watt lamp with a normal life of about 1000 hours, consumes 40 Kw-hr. during that time, which at the rate of 5c per Kw-hr. means a total of $2.00 for electricity consumed during its life, at least 15 times the cost of the lamp. Yet some imported lamps costing a trifle less have been found to be so inefficient that a 50-watt size produces hardly more light than an American 40-watt. During 1000 hours such a lamp will consume 50 Kw-hr. of electricity, at a total cost of $2.50, and the apparent saving has disappeared.
