To understand the how to read electrical drawings, you have know basic course in electrical principles. Such as ohm's law, Kirchoffs rules of circuits and some electrical codes.
So, the symbols which are used in electrical drawings, are representative of all electrical drawings and principles. You have to know the theory about these all apparatus and what are the relationship between symbols and apparatus. Every electrical equipment has its own unique symbols, a fuse has a standard symbols, a motor has a standard symbol and so on.
Keep it up and dont give up they are not so hard.
Here below are some links which will help you to more understand.
One must be acquainted with legend and electrical terminology to read and understand single line diagrams and for various equipments general arrangement one must know to read plan / elevation and sections.
Reading electrical drawings is easy. However, you must first break both arms on the architect so he quits changing the as-built prints. Then just start at a panel and follow the circuits out. The thingys that look like light bulbs are and the thingys that look like duplex receptacles are.
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"Well, I've wrestled with reality for 35 years, Doctor, and I'm happy to state I finally won out over it." Elwood P. Dowd