Lesson 1/Learning Event 2
TYPES OF CIRCUITS
Electrical circuits can be laid out in series, parallel, or series-parallel. To troubleshoot an electrical
circuit, you must be able to identify the way it is laid out and understand how current flows in the
FIGURE 12. SERIES CIRCUIT.
First, let's take a look at the SERIES CIRCUIT. A good example of this circuit is a string of series-
connected Christmas tree lights. Can you recall a time when all the bulbs on a light set quit
working because one bulb burned out? This is what happens when a series circuit is used.
The reason for all the lights going out can be easily explained by the schematic diagram of the light
set. Notice there is only one wire connected between each bulb. By following this electrical path,
the current must flow from the power source to the first bulb, through that bulb filament, to the
next bulb, through its filament, and so forth, in order to get back to the power source.