Electrical Wiring Systems- Tree, Distribution

Electrical Wiring Systems: There are two systems for tapping off Electric supply from the main, namely, Tree system and Distribution system.

Contents

Tree System

A tree system is the wiring system in which sub-circuits are tapped off from the main circuit at some convenient place.

Nowadays, this system is out of practice as there are many joints for sub-circuits.

Moreover, it is very difficult to find faults. Figure 1 shows the connection of such a system.

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Advantages of Tree system

The length of cables required for the installation of the wiring is less and therefore the initial cost is also very less.

Disadvantages of tree system

Fuses in the installation are scattered.
Location of faults is not easy.
The voltage available at different points of load will vary.
Appearance of the system is not so good.

Distribution System

Distribution System is most commonly used nowadays.

In this system, the main distribution circuits are brought to one or more distribution boxes from where it is further distributed to different branch circuits as shown in the figure.

This system is tapped off from the distribution box without interfering with the other circuit. Moreover, each circuit is independently tested to find the faults.

Advantages Distribution System

Fault finding is very easy, as there is protection for every sub-circuit.
The voltage available at different points of the circuits will be the same.
Renewal or extension of the circuits is easy.

Disadvantages Distribution System

In this system, more length of cable is required for installation.

Therefore,more initial cost of erection.

SELECTION OF WIRING

Wiring systems are of many types.

The selection of an individual system depends upon a number of factors.

When selecting a wiring system following factors must be considered.

Initial Cost: The initial cost of the wiring system adopted must be economical to suit the consumer.
Durability: The cable used in the installation of the wiring must be sufficiently sound so as to bear the changing atmosphere of the surrounding. It should also be in a position to pass the full-load current of the circuit.
Mechanical Protection: The system chosen must provide good mechanical protection to the cables used in the installation of the wiring.
Safety from Fire: This is an important factor and must be considered while selecting an individual system. The system adopted should be free from risk as far as possible.
Appearance after Completion of the Job: The wiring should appear attractive, from
this point of view concealed conduit wiring is best, but its initial cost is very high. However, C.T.S (Closed Tree System) wiring also looks attractive and has low cost of installation.
Accessibility: It should be easy to extend or repair the wiring.
Life: The system adopted should have long life.