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Title: Electrical Wiring..Domestic And Industrial


1
Government Engineering College,Patan
Assignment work
On Electrical Wiring
Elements of Electrical engineering
  • Prepared By Nikul Parmar

2
In this Presentation we will Discuss on following
Topics..
  • Introduction.
  • Electric Power supply Wiring.
  • Domestic Electric circuits.
  • Domestic Wiring.
  • Sub-circuits in Domestic Wiring.
  • Methods of Wiring.
  • Industrial Electrification.
  • Types of Installation.
  • Electrical Installation for power circuit.

3
Introduction
  • Now a day electricity Is used not only for
    domestic lighting purpose, but it is also used
    for various modern equipments, which are very
    common to various houses like geysers, washing
    machines ,mixers ,ovens ,televisions ,computers
    etc. Each consumer has a separate electrical
    circuit connecting different appliances and
    accessories. Depending upon the power, current
    and voltage ratings of various appliances, it is
    necessary to select proper type of wiring scheme
    for the domestic purpose. Thus a network of wires
    connecting various accessories for distribution
    of electrical energy from the supplier meter
    board to the numerous electrical energy consuming
    devices through controlling and safety devices is
    known as Electrical Wiring.

4
Electrical Power transmissionFrom Electric pole
to Energy meter to Distribution board
5
Domestic Electric Circuit
  • Electric power is usually generated at places
    which are far away from the places where it is
    consumed. At the generating station, the electric
    power is generated at 11,000 volts. This voltage
    alternates at a frequency of 50 Hz.
  • The power is transmitted over long distances at
    high voltage to minimize the loss of energy in
    the transmission.

6
Domestic Wiring
  • The electric power line enters our house through
    three wires- namely the live wire, the neutral
    wire and the earth wire. To avoid confusion we
    follow a color code for insulating these wires.
  • The red wire is the live wire, and the black wire
    is neutral. The earth wire is given green plastic
    insulation.
  • The live wire has a high potential of 220 volts
    whereas the neutral wire has zero potential. Thus
    the potential difference between the live wire
    and the neutral wire is 220-0 220 volts.
  • The earth wire is much thicker in size and is
    made of copper. One end of it is connected to a
    copper plate buried deep under the earth. The
    earth connection is made to the electric meter
    and then to the main switch.
  • In our homes, we receive supply of electric power
    through a main supply (mains), either supported
    through overhead electric poles or by underground
    cables.

7
  • The live wire and neutral wire, coming from the
    electric pole, enter a box fitted just outside
    our house which has a main fuse F1. The fuse is
    connected in series with the live wire. This is
    done so because it is only the live wire which
    has a high potential of 220 volts unlike the
    neutral wire which carries zero potential. The
    fuse F1 has a high rating of about 50 amperes.
    Thus it prevents any damage such as fire to the
    entire electrical wiring entering the house due
    to short-circuit or overloading.
  • The two wires then enter the electricity meter
    which records lithe electrical power consumed by
    us in kilowatt-hour (kWh). This meter is
    installed by the electric supply Department of
    our city.
  • These two wires coming out of the meter are then
    connected to a main switch which is placed in a
    distribution box. Another fuse F2 is placed in
    series with the live wire in this box for the
    sake of consumer safety.
  • There are two separate circuits in a house namely
    lighting circuit and power circuit. The lighting
    circuit with a 5 A fuse is used for running
    electric bulbs, fan, radio, TV, tube lights etc.
    and the power circuit with a 15 A fuse is used
    for running electric heater, electric iron,
    geyser, refrigerator etc as it draws more current.

8
  • The distribution circuits are always connected in
    parallel combination. In a parallel circuit even
    if there is a fault or short-circuiting in any
    one line, the corresponding fuse blows off
    leaving the other circuits and appliances intact
    and prevents damage to the entire house.
  • In case short-circuit occurs in the power
    circuit, then the power-fuse will blow off but
    our lights will continue to burn as the lighting
    circuit remains unaffected.
  • A constant voltage of the main line is available
    for all other electrical appliances.
  • Along with the two wires, a third wire called the
    earth wire also enters our house as shown in the
    fig. The earth connection is first made to the
    electric meter and then to the main switch. This
    wire then goes into the rooms along with the live
    and neutral wires.

9
Sub circuits in Domestic wiring
  • It is Broadly classified into two categories
  • Light and Fan sub-circuit and Power sub-circuit.
  • (1) Light and Fan Sub-circuit
  • The sub-circuit of the electrical
    installation feeding supply to various light
    points, i.e. lamps, tubes etc. and to fan points
    is termed as light and fan sub-circuit
    respectively.
  • (2) Power circuit
  • The part of the complete installation that
    supplies appliances like hot plate , electric
    iron ,small single-phase motors of washing
    machine , refrigerator etc. is generally called
    the power sub-circuit.
  •  

10
Methods of Wiring
  • Wiring (a process of connecting various
    accessories for distribution of electrical energy
    from suppliers meter board to home appliances
    such as lamps, fans and other domestic appliances
    is known as Electrical Wiring) can be done using
    two methods which are,
  • I. Joint box system or Tee system
  • II. Loop in system.

11
  • Joint Box or Tee or Jointing System
  • In this method of wiring, connections to
    appliances are made through joints. These joints
    are made in joint boxes by means of suitable
    connectors or joints cutouts. This method of
    wiring doesnt consume too much cables size.
  • You might think because this method of wiring
    doesnt require too much cable it is therefore
    cheaper. It is of course but the money you saved
    from buying cables will be used in buying joint
    boxes, thus equation is balanced. This method is
    suitable for temporary installations and it is
    cheap. 

12
  • Loop-in or Looping System
  • This method of wiring is universally used in
    wiring. Lamps and other appliances are connected
    in parallel so that each of the appliances can be
    controlled individually. When a connection is
    required at a light or switch, the feed conductor
    is looped in by bringing it directly to the
    terminal and then carrying it forward again to
    the next point to be fed.
  • The switch and light feeds are carried round the
    circuit in a series of loops from one point to
    another until the last on the circuit is reached.
    The phase or line conductors are looped either in
    switchboard or box and neutrals are looped either
    in switchboard or from light or fan. Line or
    phase should never be looped from light or fan.

13
  • Advantages and Disadvantages of Loop-In Method
  • Advantages
  • It doesnt require joint boxes and so money is
    saved
  • In loop in systems, no joint is concealed
    beneath floors or in roof spaces.
  • Fault location is made easy as the points are
    made only at outlets so that they are accessible.
  • Disadvantages
  • Length of wire or cables required is more and
    voltage drop and copper losses are therefore
    more.
  • Looping in switches and lamp holders is usually
    difficult.

14
Industrial Electrification
  • To increase the productivity and to avoid the
    accident hazardous, factory lighting should
    fulfill the following requirements.
  • i It should produce sufficient illumination on
    the working plane.
  • ii It should provide uniform distribution of
    illumination.
  • iii It should avoid glare and shadows.
  • iv It should be easy to clean.
  •  

15
Types of Installation
  •  
  • 1.General Lighting
  • Under this scheme general lighting should be
    provided such that there will be uniform
    distribution of light over the working plane.
  • In such cases, the color of walls and
    surroundings are selected in such a way that it
    adds effectiveness to the Illumination. Generally
    White color is preferred.
  •  
  • 2.Local Lighting
  • There are certain locations where fairly intense
    illumination is required.
  • To provide sufficiently more illumination for
    such locations, local lighting is provided.
  • Local lighting is provided by means of adjustable
    fittings attached to the working plane and lamps
    are mounted on reflectors to avoid the glare.
  • 3. Emergency Lighting
  • There are some applications where emergency
    lighting has to be provided such as
  • Control posts , first aid centre and speedy
    evacuation of personnel after main lighting
    circuit is off.

16
Electrical Installation for power circuits
  • According to Indian Electricity Rules(No. 50 and
    51), the wiring of electrical motors in
    industries is to be carried out apart from
    meeting local requirements on various conditions.
  • Design consideration in case of motor wiring
    installation is different from that of the
    lighting wiring installation. In case of lighting
    load, size of the conductor l wire is decided on
    the total current of the load.
  • But in case of motor wiring, size of the
    conductor should not be less than corresponding
    to 300 percent of the motor full load current.
    The reason is that conductor should be capable of
    withstanding the starting current of the motor
    which is generally 5 to 7 times the full load
    current. Therefore , each motor is fed separately
    from the main distribution board. If there are
    more than one motor on single branch circuit,
    then the rating of the conductor will depend on
    the total load of all motors in that circuit plus
    starting current of the largest H.P. motor.

17
  • Electrical Installation of Power Circuits

18
  • Each motor takes a high current at the starting
    which may be 5 to 7 times full load current of
    the motor. Hence, to limit the voltage drop in
    the cable as well as to limit huge starting
    current, a separate starting device, called
    starter is used for each motor. Starter is
    located after the motor switch.
  • In domestic installations, single earthing is
    sufficient but in workshops or factory , double
    earthing is necessary from the extra safety point
    of view.
  • The conduit used in power wiring shall be
    electrically continuous throughout and connected
    upto the frame of the motor. The frame of the
    motor shall be earthed by the owner by two
    separate and distinct connections to the earth
    (IE Rule 61).
  • The conduit should preferably be laid in covered
    trenches to facilitate operator movement. Laying
    of cables must be in separate conduits for
    separate motors.

19
Bibliography
  • Reference sites
  • www.google.com
  • www.Electricaltechnology.org
  • Reference Books
  • Elements o Electrical Engineering(Author U.A.
    Patel)
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