The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Practical Electricity And House Wiring
Polarizing And Grounding
Black, White Wires.—In Chapter 4, in drawing our diagrams we used a light line to designate a white wire, a dark line to represent a black wire, to make it easier to trace the circuits. In actual wiring, one white wire and one black wire are actually always used, not for convenience in tracing, but for other purposes to be mentioned later. The Code requires that a white wire always be run without interruption by a switch, fuse or any other device, from the main switch to each and every 115-v. outlet; on the other hand the other wire from any outlet where electricity is taken from the wires, back to the main switch, must be black or some color other than white or grey. If a wall switch is used for example to control a ceiling light, the wire from the light to the switch, and from the switch back to the main switch, must be black (or some other color, but never white).
Other Colors.—In wiring it is often necessary, particularly in larger buildings, to run a great number of wires through the same conduit; if all were black it would be difficult to trace them and identify them, therefore different colors such as red, green, etc., are used for the purpose.
Polarizing.—This process of definitely identifying the two wires in any circuit is known as "polarizing" and must be religiously done in every installation. The white or grey wire is known as the "neutral" wire, and the other one is commonly known as a "hot" wire.
When you come to actual wiring, you will find that on all devices except switches, one of the terminals is of a whitish color, which might also be described as silver or tin color; all other terminals are natural brass color. The white wire connects to the whitish colored terminal, black wire to the natural brass terminals. On switches all terminals are natural brass color because as covered in previous paragraph, only black wires connect to switches.
Polarizing serves a very definite purpose which can be understood by not only reading but carefully studying the rest of this chapter. Its main object is safety, reducing to a minimum any possible danger of shock through accidental contact with the wires. It must be remembered that while 115 volts is not a particularly high voltage, and not ordinarily considered dangerous to human life, still under certain conditions death does result from voltages even lower than this.
Grounding.—The ordinary wiring in a home consists of a 3-wire system, explained in the previous chapter, with 230 volts between the two black wires, and 115 volts between either black wire and the white neutral wire.
