CHAPTER 2 Installation circuit and Systems

Two methods of distribution of electrical energy
Distribution board System
The tree system
Distribution Board System
The fuses of various sub-circuits are grouped together at a place close to main switch

1. CHAPTER 2 Installation circuit and Systems

2. 2.1. Distribution of Electrical Energy Two methods of distribution of electrical energy Distribution board System The tree system Distribution Board System The fuses of various sub-circuits are grouped together at a place close to main switch

3. 2. The Tree System smaller branches are taken from the main branch. A fuse is inserted at the start of each branch It has the following disadvantages Voltage across all the lamps doesn't remain the same The lamp in the last branch will have less voltage across them due to voltage drop in the leads. A number of joints are involved in every circuit The fuses are not at one place Fault location is difficult. If a fault occurs, all the joints in the wiring will be inspected thoroughly to locate the fault.

4. The Tree System

5. Wiring systems Is a net work connecting various accessories with energy consuming devices and equipments to distribute electrical energy from supplier to the load. Cleat wiring Sheathed cables wiring All insulated cables wiring 2. Catenaries wiring 3 . Conduit system 4. Trunking system

6. 1.Cleat wiring system PVC-insulated cables are supported on cleats made of porcelain/ceramic or plastic .

7. 2. Catenaries wiring System Designed to take supplies from one building to another by overhead means, For building with high ceilings . In this system, insulated cables are carried on a steel wire strained between two points.

8. 3. Conduit wiring Systems Conduits are installed on the surface of walls by means of pipe hooks or Buried under the walls and cables are drawn into them.

9. Cont….. As this system of wiring provides protection against fire, mechanical damage and dampness/humidity, it is used for:- Places where considerable dust is present , such as in textile mills, saw mills, flour mills etc, Damp situations In workshops for lighting and motor wiring Places where there is possibility of fire hazards such as oil mills varnish factories, etc. Places where important documents are kept. ex. Record rooms. Places where appearance is prime importance.

10. 4. Trunking is a fabricated casing for conductors and cables rectangular in shape with a removable lid which allows the conductors to be laid in rather than be drawn in as is the case with conduit. It is used where a large number of conductors are to be carried, or follow the same route. Both steel and PVC trunking are available, with a wide range of such accessories as bends, tees, risers and reducers.

11. Trunk

12. Consider the following d uring Choice of wiring system Safety Mechanical protection Permanency Appearance Accessibility Cost

13. Drawing Representation of circuits Wiring diagram: A wiring diagram or connection diagram shows the detailed connections between components or items of equipment

14. Schematic Diagram A schematic diagram shows most clearly how a circuit works. All the essential parts and connections are represented by their graphical symbols

15. Single Line Diagram: A diagram showing number of conductors needed and lay out (electrical) symbols of the accessories.

16. Methods of Wiring Two methods 1.Junction box (Joint box) method 2.Loop in method Joint box method less wire length but with extra box cost Fault location may be difficult Fixing require skill Should be located at accessible position

17. Junction Box method

18. Looping-in method 2. Loop-in method

19. commonly employed for domestic installations The main advantages are: i . No junction boxes are required ii. Since no joints are concealed in walls and roof spaces, they are made only at outlets and switch boards. iii . The connections are accessible for inspection and hence fault location is easy. The main disadvantage is: The cable required is more and hence voltage drop and copper losses are comparatively more. Loop-in method

20. Jointing and terminations of wires Jointing: There are many different ways of joining two conductors together. The screw connector

21. II. Junction box III. Soldered joints :

22. Terminations : When a cable conductor is finally connected to the apparatus it is supplying, a safe and effective termination of that conductor must be made. PVC singles into screw terminals Do not leave bare conductor showing outside the terminal

23. Lug terminations : frequently used for connecting a conductor to a bus-bar.

24.   Termination into appliances : Usually termination of cable into appliances, especially the portable type, should be firmly connected at or near the point of entry

25. Electric Bell Circuits Constructed from electromagnetic materials Types of Bell Single-stroke bell Trembler bell (vibrating) Continuous ringing bell

26. Single-stroke Bell Application This type of bell is frequently used on railways and mines , as it can be used for signaling purposes. It may also be used in many other situations where a longer signal would disturb office workers.  

27. Trembler Bell Application : The trembler bell is the one most commonly used as a door bell for houses and offices.

28. Continuous Ringing Bell This is a trembler bell with mechanical and electrical arrangements such that the bell continues ringing after the bell- push has been released . Application This type of bell is useful for alarm circuits of various kinds.

29. Bell Pushes and Contacts In the main bells are operated by means of bell-pushes.

30. END OF CHAPT 2 !