Electrical Wiring..Domestic And Industrial

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Government Engineering College,Patan
Assignment work
On Electrical Wiring
Elements of Electrical engineering

• Prepared By Nikul Parmar

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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.

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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.

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Electrical Power transmissionFrom Electric pole
to Energy meter to Distribution board
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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.

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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.

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• 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.

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• 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.

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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.
•  

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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.

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• 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. 

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• 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.

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• 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.

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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.
•  

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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.
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• 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.

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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.

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• Electrical Installation of Power Circuits

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• 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.

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Bibliography

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