22. Steps in Reading Electrical Wiring Plan
1. Familiarize with the Standardized Electrical Symbols
Knowing what the symbols in your electrical drawing mean will help you find
different appliances. Symbols usually resemble specific meaning.
Familiarize yourself with descriptions for electrical appliances, understanding that
different symbols appear for different objects. Refer to Basic Electrical Symbols and
Their Meanings for specific resources and learn these symbols visually. You'd better
get to know the following basic symbols by heart.
23. Steps in Reading Electrical Wiring Plan
2. Learn Reading Pattern
Read schematics in the pattern that you would read text. With rare
exceptions, schematics should be read left to right and top to bottom. The
signal being generated or used by the circuit will flow in this direction. The
user can follow the same path that the signal uses to understand what the
signal does or how it is being modified.
24. Steps in Reading Electrical Wiring Plan
3. Identify Polarity
Some components to a circuit board are polarized, meaning one side
is positive and the other negative. This means you have to attach it in the
specified way. For most symbols, polarity is included in the symbol. To
identify the polarity of the physical part, a general rule of thumb is to find
out which metal lead wire is longer. The longer part is the + side.
25. Steps in Reading Electrical Wiring Plan
4. Understand Names and Values
Values help define exactly what a component is. For electrical
components like resistors, capacitors, and inductors the value tells us how
many ohms, farads, or Henries they have. For other components, like
integrated circuits, the value may just be the name of the chip. Crystals might list
their oscillating frequency as their value. Basically, the value of a
schematic component calls out its most important characteristic.
26. Steps in Reading Electrical Wiring Plan
Component names usually consist of one or two letters and a number.
The letter part of the name represents the type of component - R's for
resistors, C's for capacitors, U's for integrated circuits, etc. Each component
name in an electrical drawing should be unique; if you have multiple
resistors in a circuit, for example, they should be named R1, R2, R3, etc.
Components names help us reference specific points in schematics.
The prefixes of names are pretty well standardized. For some components,
like resistors, the prefix is just the first letter of the component. Other name
prefixes are not so literal; inductors, for example, are L's (because current
has already taken I [but it starts with a C...electronics is a silly place]).
Here's a quick table of common components and their name prefixes:
