The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Practical Electricity And House Wiring
In locations where appearance is no great factor, such as basements, attics, etc., it is well to place a good reflector above every lamp. Experience shows that a 40-watt lamp with reflector usually gives more useful light than a 60watt without a reflector.
No home is complete without a doorbell transformer, costing practically nothing to operate, to replace dry cells ordinarily used.
Wiring Methods
The National Electrical Code permits wiring to be done using any of a great variety of methods. In this book will be discussed only those methods used in residential and farm wiring. In this chapter will be described the basic principles of each method, and installation details that are common to all methods. Specific instructions for each method will be given in later chapters.
Knob-and-Tube System.—In the "knob-and-tube" system, ordinary rubber-covered wire is used, but wherever the wire comes close to wood or other combustible material, it is supported on porcelain knobs or cleats; whenever it passes through wood, porcelain tubes are first installed through which the wire is run. See Fig. 82.
If all the wires are exposed, the system is known as "exposed knob-and tube," but if the wires are concealed inside walls, then it becomes "concealed knob-and-tube work." Slightly different rules apply for the two variations of this system, which will be covered in a future chapter.
Armored Cable System.—Armored cable is very extensively used—it was illustrated in Fig. 49. This material is available under a variety of trademarks such as "BX," "Flex-steel," etc. It consists, as explained in Chapter 5, of two (or more) rubber-covered wires, over which is a layer of heavy craft paper, and over that a continuous spiral wrapping of steel, each turn interlocking with the next so that the complete assembly is very flexible. The paper protects the wire from abrasion by the steel and against injury while the steel is being applied, and also serves another important purpose that will be explained in a later chapter. The steel itself protects the wires against mechanical injury, also serves the useful purpose of "grounding" covered in Chapter 8.
