Friday, 3 April 2015

Make a wiring installation for a small residential building



Make a wiring installation for a small residential building
Hello, friends how are you. Thanks for coming to my blog.
Today , I am going to discuss  how you can prepare estimate for a wiring of a small residential building.  I first did the wiring in my own home. All the connection was very simple. But various type of problems appeared when I switched on the appliances.   A heater or an induction heater draws a larger current from the supply,. As a result a large voltage drop appears in the line. By mistake I connected a light bulb very near to the induction oven. As a result the bulb dims.
So, it is not so easy that you are thinking. For a big building it becomes more complex and complicated. There are several rules to be followed by an electrician according to the Indian standard.
You must carry out these steps during the project
1.at first you must study the plan of the building
2.then you calculate the total load for the building
3.make a survey of the building and then decide where you want to install the electrical distribution points
4.calculate all the required specification of the instruments like main switch, conduct pipe, earth wire3, distribution board, conductor sizes etc.
5. then draw the wiring diagram and estimate the material required and it’s cost.

GUIDELINES (Indian standard) FOR DOING THIS PROJECT
1.make a lay out plan of the building which comprises various types of rooms like offices, lecture rooms, drawing halls, workshops etc.
2.in lay out plan of the4 building, a single line circuit diagram will show all the  electrical points.
3.you can  use any of the following types of wiring. (a)wood casting wiring. (B)batten wiring, (c)rigid steel wiring, (d) pvc sheathed wiring.
4. make separate two different lines. One is for light fans, and another for high current appliances like pump, heater, motor etc.
5.energy meters should be place in a easily accessible place.
6. use the circuit breakers of proper value. And place them in human reach. So one can easily exchange it.
7.use colour codes in the connecting wires. For three phase live line should be red , yellow, blue in colour and the neutral should be black.
8.all switches must be installed on live not in neutral.
9.all portable appliances must be earthed using three pin plug.
10. After the main switch, supply should  brought to the distribution boards  for lighting and power circuits separately. Branch distribution boards should be provided with a fuse on the live conductor of each circuit while neutral conductor of each circuit should be connected to a common link capable of being disconnected individually for testing purposes. One spare circuit of adequate capacity should be provided on each branch of the distribution board.

11. lights and fans may be connected in the same circuit. Each sub-circuit should have not more than a total of 10 points including light fans and 5amp socket outlets. The load on each sub-circuit should not be more than 800 watt. If a separate circuit is installed for fans only, the number of fans in the circuit should not exceed 10. In each house at least two lighting sub circuits may be provided so that in case of fault in one sub-circuit the whole house is not plunged into total darkness.
12. if the load on any power sub circuit exceeds 3000watt , the wiring for that sub circuit should be done in consultation authorities.
13. lighting arrangement is a very important thing in house wiring.  The need of illumination is different for different purposes . here I give you a chart which will help you to choose a proper lighting arrangement.
location
Illumination level in lux
study
300
garage
70
stairs
100
Supply workshop
200
sewing
700
bathroom
100
kitchen
200
Table games
300
Dressing rooms
200
bedroom
300
Dining room
200
Living room
300
entrances
100
Play ground
1000
14. always provide a switch at the entrance for lighting purposes.
15. two  way switches should be provided in case of large hall room and stairs.
16. in bedroom locate some switches near the3 bed for lighting and emergency purposes.
17. switches for bathroom must be located outside.
18.3-pin, 5amp socket outlets should be provided for all lights and fans and 15amp socket for power circuit.
19. A voltage drop happens when a electrical equipment is connected to line. This voltage drop must not exceed 3% for general equipment and 5% for power equipment.
SIZE OF THE CONDUCTOR
The minimum size of aluminium cable is 1.5 sq mm for lighting circuits and 205sq mm for power circuits. For determining the load in amperes, in a particular circuit, distance of load centre from distribution board should be calculated. Size of the conductor can be calculated by the following formula
Size in square mm= (2*K*L*I)/(permissible voltage drop)
Where,
K= resistivity in ohm mm^2/m
L= distance of load centre from distribution board.
Value of the K , may be taken 0.03for aluminium and 0.02 for copper conductor.
These are the basic instruction. After installation is over some testing must be done before powering. I will discuss about that in my next post. Keep visiting my blog.
Thank you very much, have a nice day.