Types of electrical circuit connections - Basic tutorial on series and parallel circuit

There are mainly two basic types of circuit connection in an electrical system. These two basic configuration are most commonly known as the series connection and the parallel connection.

Although there are a lot of other complex circuits constructed from various designs and installation purposes to suit specific electrical requirements, all of them are based from a combination of these two basic wiring principle.


The best way to understand the difference between the two is that, in a series circuit, a broken or open component in any one of the devices connected in series will result in an incomplete or open circuit. Whereas in a parallel circuit, any broken device connected in parallel will not break the circuit.

Series Circuit

With a series connected circuit, each electrical component are successively connected one after the other in sequential order as shown in Fig.1. The absence of branches in the circuit causes the current to flow through only one straight path starting from the power source to the load.

Since each connected load are known to possess some form of resistance, then the more the load connected in series order will result in higher resistance in the flow of current to the succeeding load in the circuit.

Fig.1 Typical Series Connected Circuit

More resistance in a series circuit will result in higher impedance which will impede or limit the flow of current to cause restriction in supplying voltage to each load successively connected in the circuit, which in effect reduces the amount of voltage supplied to the final receiving load.

Fig.1 shows two resistors R1 and R2 seriesly connected between the power supply and the lamp. The sum total of these two resistors acting on the circuit depletes the amount of current going to the lamp, resulting in a poorly illuminated lamp. Whereas if we are to remove R2 and leave only R1 connected in the circuit, then more current could flow since R1 is the only resistor that is getting in the way of the current to flow freely between the power supply and the lamp.

Parallel Circuit

With parallel connection, the circuit is constructed in a manner so that the connected loads are arranged across each other to form a branching of circuit. Unobstructed flow of current is established through this type of circuit, and equal amount of voltage is supplied to each load in the branch.

Fig.2 Typical Parallel Connected Circuit

Fig.2 shows a wiring configuration with no obstructions to interfere the current to flow freely to reach the lamp since resistors R1 and R2 are both connected in parallel across the lamp. The same voltage is supplied to both resistors and the lamp in this case, which in effect will make the lamp glow brighter.

Parallel connection is done by connecting the consecutive load between two points across the preceding load as shown in Fig.2, hence there is no reduction or restriction on the flow of current in the circuit, allowing each connected load to receive the same amount of voltage equally distributed in any branch of the circuit, which makes it the most ideal circuit connection in home wiring installation.

Important Note: Understanding these two types of circuit configuration is a prerequisite to learning how to use the electrical multimeter effectively.