Unit-II

1. Electrical Systems in a Building
Unit-II
Building Utility & Services

2. Syllabus

3. Introduction
• Since the end of the nineteenth century virtually all buildings are
provided with electric lightings installation for use at night. With
the advent of fluorescent lamp that is compatible with daylight,
cheap to run and not emitting heat gain in buildings, it made possible
to install electric lighting supplementing day light and in extreme
cases provide the only source of light in a windowless environment.
• Several factors can exercise a critical influence on the success of
lighting installations apart from proper level of illumination on the
work plane.

4. Introduction

5. Introduction
• The first use of electric supply were established in 1882 by
Thomas Edison, Thereafter there have been constant effort
throughout the world to set-up power stations for more than one
purposes.
• The power generation in India in 1947-48 was only 4.1 billion and
today we generate more than 600 billion kw.

6. Electricity

7. Electricity Generation

8. Electric Generator
• Electricity is generated from the stored energy of water that
makes turbine run and generate electricity. The other method
includes fuels (Coal, diesel or gas) to fire boilers and pass stream
and generate electricity through generators. Transformer step up
several thousands or even hundreds of thousands of volts before it is
supplied to the transmission lines or cable. By transmitting electricity
at high voltages less power is lost in the cables. At the receiving end of
voltage is stepped down by transforms in local sub-stations to
consumers at 240 volts.

9. Electric Generator

10. Entry in the buildings
• In Urban areas electrical cables are Usually underground and are
brought up to entry point at ground level or into basement service cable
cannot be bent to small radiee and this should be borne in mind when
considering point of entry. In small buildings the cable run is kept as
short as possible, terminating in a distribution board at the first
convenient position. In these buildings the distribution board will be fitted
with a seal box to prevent moisture from entering the insulation of the
service cable, a main fuse for the premises in a box sealed by the supply
authority and the consumer unit or other switch and fuse gear
belonging to the building. The position chosen for the distribution board
should be readily accessible both for meter reading and for replacing fuses.
In some cases special glasses are provided so that meter can be read without
entering the premises.

11. Entry in the buildings

12. Domestic Supply
• Domestic electricity supply usually effected through distribution system
and describe as single and three phases. Normally small buildings are
supplied with electricity by two wires, one phase wire and the other neutral.
This is known as single phase supply and gives a voltage for the
premises of 240 volts. The loading of the supply wiring is balanced
between the phases by using the phases in rotation so that each one services
every third building.
• In three phases, four wire bring 420/ 240 volts, 50 cycle per second. The
voltage. The voltage between any two of the phases wires is 415 Volts.
And between any phase wire and the neutral is 240 volts. The balancing of
load is then achieved by serving different areas of the building by different
phases. Electric motor are usually designed for three phase operation.

13. Single and Three Phases Distribution

14. Earthing System
• In electricity supply systems, an earthing system or
grounding system is circuitry which connects parts of
the electric circuit with the ground, thus defining the
electric potential of the conductors relative to the
Earth's conductive surface

15. Earthing System
• Regulations for earthing system vary considerably among countries
and among different parts of electric systems. Most low voltage
systems connect one supply conductor to the earth (ground).
• People use an earthing system mainly for these applications:
• To protect a structure from lightning strike, directing the lightning
through the earthing system and into the ground rod rather than
passing through the structure.
• Part of the safety system of mains electricity, preventing problems
associated with floating ground and sky voltage.
• The most common ground plane for large monopole antenna and some
other kinds of radio antenna.

16. Applications Of Earthing
• Protect human against lightning and earth fault condition
• Protect the premises against lightning and earth fault condition
• Provide low resistance and safe path for lightning and fault current
• All metallic enclosure and extraneous conductive parts are at
equipotential
• LV System Earth

17. Applications Of Earthing

18. Functions of Earthing
Equipment Earth : Path for fault current, lower touch voltage, protection
against electric shock
Lighting Earth : Low resistance path to diverse the current under lightning
attack.
Telecom Earth : Signal Earth, reduce noise and interference, stabilize DC
supply voltage and prevent electric shock
Computer Earth : reduce interference, maintain supply voltages

19. Functions of Earthing

20. Two classes of protection
Class I protection –
use of barrier/insulation and connection of protective conductor to
equipment metallic enclosure in order to protect against electric shock
Class II protection –
beside of the basic insulation, addition layer of insulation apply to the
enclosure. Therefore no extraneous conductive part. The additional
layer is independent to the basic insulation so that under failure of
basic insulation, it offers additional protection

21. Two classes of protection

22. Types of Earthing
• Supply System – Neutral Earth
• System Earth
• Electrical Safety Earth
• Lightning Earth
• Generator Earth
• Protection Earth (i.e. surge arrestor)
• Telecom / Computer Earth
• Shielding Earth
• Integrated Earthling System (Advocated)
• Electrostatic Earth (Clean Room / Hospital)

23. Earthling Arrangements
• TN System
• TNS System
• TN C S System
• TN C system
• TT System
• IT System

24. Domestic Supply

25. Distribution Circuits
• In most of the buildings electricity supply is divided into two types of sub
circuit: Lighting Load sub-circuit and power load Sub Circuit and
finally for operation purpose into three phases circuit-lighting, socket
outlets and fixed apparatus.
• The sub circuit which gives supply to lighting load points is called lighting
load sub circuit. This circuit includes lamps, fans, tubes etc. As per Indian
Electricity Rules. The following rating should be assumed
• Filament lamp 60 W
• Ceiling fan 60 W
• Socket for radio, table fan 60 W
• Flurecent tube 40 W
• Mercury Vapour lamp 80 W

26. Basic wiring Systems
• Wiring in buildings is run either on the surface or canceled in the
construction. Surface wiring is cheaper but its appearance limits its
use. The type of wiring system available for use in buildings are
sheated and conduit. Two or more wires consisting of metal
conductors each having its own inuation is enclosed in a protective
sheath known as TRSC tough rubber sheated.
• Use of PVC for insulation and sheating is preferred as it gives
smoother and neater cables. This type of wire are well suited to
surface use. For use in concealed wiring, conduit or metal channels
should provide to protect wiring.

27. Basic Wiring Systems

28. Basic wiring Systems
• Types of wiring
• There is wide choice of wiring; however one must keep in mind the safety
of men & material. The various types of wiring used are discussed below
• Cleat Wiring
• In this system of wiring, V.I.R or PVC Insulated wires are held to the walls
and ceiling by means of porcelain cleats which are fixed at distance of 0.5
m horizontally and 0.75 m vertically above the walls The cleat are made on
two halves, one is known as base and the other is known as cap. The
wirings are drawn in groves and finally tightened. This wiring is cheapest
and require little skill and can be quickly installed.

29. Cleat Wiring

30. Basic wiring Systems
• Wooden Casing , Capping Wire
• In this type of wiring, the casing is fitted on the walls and ceilings on
the wooden gutties which are fixed The size of casing and capping
generally used is 20 mm x 12 mm for house wiring. This type of
wiring is generally used for house wiring. It is cheaper as compared to
lead sheated and conduit wiring, easy to Install.

31. Basic wiring Systems

32. Basic wiring Systems
• Lead Casing Wire
• In this system of wiring, the wiring procedure is same except the wire
used in VIR covered with an outer sheath made of lead-aluminum
alloy It is used in houses and industrial wiring. It has good mechanical
protection and possibility of fire is less.

33. Basic wiring Systems
• C.T.S & T.R.S or PVC wire
• In this system of wiring first of all teaks wood is fitted on the walls
and ceiling. The battern is tightened by drawing wooden screws in the
gutties fitted in the wall an ceiling. PVC or CTS wire run on the
battern and finally grappled by the joint clip. This type of wiring is
suitable for domestic installations, commercial & Industrial buildings
except where it is liable to mechanical injury.

34. C.T.S & T.R.S or PVC wire

35. Basic wiring Systems
• Conduit Wiring
• In this type of wiring system VIR or PVC are carried through steel or
PVC tubes as conduit in case of surface conduit wiring, the conduit is
fitted on the surface of the walls by means of saddles and in case of
concealed conduit wiring the conduit to facilitate the drawing of wires

36. Ducts for Electrical Distribution
• In addition to the wiring systems there are a number of ducts available specially designed
to contain electric cables in particular building stations
• Duct tube: It consists of an inflatable rubber tube, which is placed, in concrete formwork
before pouring concrete. After the concrete has set the duct tube is deflated, withdrawn
from concrete, leaving a duct for electric wiring, or other purpose.
• Skirting trunking: It is very usual to run cable trunking in or above the skirting round
the perimeter walls. This systems is mostly employed in office buildings.
• Floor Trunking: System is employed in large offices where desks are placed remote from
walls. Useful where there are comparatively few points, the positions of which are known,
and where flexibility for future re-planning must be achieved.
• Overhead distribution
• Overhead distribution systems are clearly more economical and more flexible than under
floor ones. They are mainly used in industrial units when pendants connection to
apparatus is not considered unsightly.

37. Ducts for Electrical Distribution

38. Ducts for Electrical Distribution

39. Conductor
• Cables
• A cable is a length of single conductor, usually having several
wires stranded to-gather, or of two or more conductors, each provide
with its own insulation and laid up to-gather. The insulated conductor
(s) may or may not be provided with an overall protective covering.
The conductor with its insulation but without mechanical protection is
called core of the cable. Thus a, cable consists of three parts:
Conductor, Insulation and External Protection

40. Conductor

41. Insulations
• On the basis of of insulations, the cables maybe classified as follows:
(i) Paper Insulated cables. In these cables paper is wound on the
conductor in successive layer to archive required dielectric strength.
Such cables are manufactured in various sizes from 5 mm2 to 500
mm2 cross-section conductors and voltage rating sup to 33 kv
• (ii)PVC cables
• (iii) Oil filled insulated cables
• (iv)High Pressure of filled cables
• (v) Compressed gas insulated cables
• (vi) Vulcanized cable

42. Insulations

43. External Protection
• Against mechanical damage or electrochemical attack, fire or any other
deterious influences external to the cables can be minimized. If certain
points are taken in account
• Abrupt bending in cables is not desirable; the bending radius ranges from
12 to 30, times the diameter..
• Cables should be at least 1 m away from the foundation of the buildings.
• Cables should be at least 0.5 m away from the communication cables
• Whenever a cable crosses a road or railway line, it should be laid in pipes or
conduits.

44. External Protection

45. Electrical appliances
• There are many ways in which electricity can be used to save labour in
the home. A vast number of appliances are designed to run on the
ordinary domestic supply. The three basic application of electricity are
– the production of heat, light and power and in many devices they are
used in combination. Electronic appliances such as radio and
television sets, and record players constitute a fourth class and
telephone a fifth.
• All the electrical appliances requiring a current of more than 5 A
should be fitted with an earth or ground wire to safe guard the
user against shocks from leakages of current. Their supply cables
thus carry three-pin plugs, and in the best type of socket no current can
flow until the earth-pin can be made its contact.

46. Electrical Appliances

47. Electrical appliances
• There are four main ways in which electricity can be converted into
light
• It can flow through a wire, so that it glows(lamps), modern filament
lamps use coil of tungsten wire which gives a much whiter light than
carbon, and the bulb contains nitrogen and argon. Most household bulbs are
25 to 150 watt of electric power, but some large tungsten lamps used in
search lights an in television studios use as much as 30 kw.
• Discharge lamps are long tubes containing a gas or vapour. When
electricity passes through a pure gas at low pressure, energy is transferred to
the gas atoms, causing them to emit radiations. The wavelength of this
radiation, which determines color, depends on the gas e.g., sodium vapor
and neon emit visible radiation. Sodium produces an efficient yellow light,
mercury produces a bluish white light and some ultra-violet radiations, and
neon gives off a strong red light.

48. Electrical appliances

49. Electrical appliances
• Fluorescent lamps
• Works by the conduction of electricity through mercury vapor. This causes the
emission of ultra-violet radiation. The inside of the tube is coated with a
fluorescent powder, or phosphor. This glows with a visible light when it is struck
by invisible ultra-violet rays. The light is usually white, but it can be colored by
adjusting composition of the phosphor. Sometimes, instead of tubes, flat panels of
glass may be used as light sources. Some phosphors, such as zinc sulphide, emits
light when a voltage is applied across them. This is known as electro
luminescence..
• A carbon lamp consists basically of two carbon rods connected to an electricity
supply. An electric arc is maintained between the rods and a very intense light is
produced in this way from a compact source, such lamps are used in motion
picture projectors.

50. Electrical appliances

51. Electric Installations
• Electric Installations
• Electric Installations require necessary design, planning taking into consideration
the whole requirement of the activities to be carried out in the building. The
following steps are suggested for the same..
• Planning & Designing
• Layout of working drawings
• Application to electric supply company for granting estimated low supply and
requirement of sub-stations/ transformers
• Laying conduit for underground supply lines before concreting and completing the
plinth work.
• Laying conduits in slabs and beam reinforcement, fixing of fan hooks/ boxes in
slabs reinforcement for main supply to consumer units/ rooms

52. Electric Installations
• Physical marking of layout of wiring in all units/ rooms.
• Providing & laying complete wiring
• Fixing all fittings and fixtures and complete electrical installations
• Testing of Installations
• Providing consumer meters.
• Submission of test reports to electric supply company for supply connection
after obtaining NOC from PWD in cases of building exceeds 15m height.
• Checking of electrical installation by authorized officer of electrical supply
company before passing & sealing of meters.
• Permanent electric supply connection to buildings and consumer thereof.

53. Electric Installations
• Design & Planning
• The design and planning of an electrical Installation is governed
by the type of user of the building and requirement of the
consumer thereof. Therefore it is essential to consult competent
electrical engineer/ licensed electrical contractor at the planning
stage for providing and planning electrical installations, which should
be safe and efficient in its use and adequate for its intended purpose.
For designing layout of electrical installations for specific
requirement of power use it is essential at planning stage that the
architect in consultation with structural engineer, electrical
engineer and owner/developer to decide about following

54. Electric Installations

55. Electric Installations
• Needed accommodation for making provision of sub-station, meter
room, switch room, services cable duct, rising mains and cables,
opening and chases required in floors and walls for intending electrical
installations.
• Total load requirement i.e. lights, fans, power etc.
• Anticipated future increase in power consumption. Requirement of
electric supply company including location and distance of main supply
connection point.
• Layout of wiring installation, whether open conduit or concealed
• After collecting necessary information and suggestions from other
consultants the architect should prepare detailed working drawing of
complete electrical installation in consultation with licensed electrical
contractor

56. Electric Installations

57. Execution
• The execution of entire electrical Installation should be carried out
under the guidance and supervision of competent electrical
engineer/through licensed electrical contractor; in accordance to the
design and specification provided in the tender and strictly as per rules
and regulations of electrical supply.
• The electrical contractor should decide his sequence of work in
consultation with the architect in such a manner that it will not
affect/conflict with working of other agencies and it will allow other
service agencies to work smoothly and simultaneously without any
interruption.

58. Execution
• The electrical contractor should get approval for all materials
including fitting and fixtures to be used from the architect before
commencement of work.
• The contractor should arrange temporary electrical supply for
construction purpose; before proper work is commenced.
• At the end of work the electrical contractor should check and test
the entire electrical installation work and get it approved from the
electrical supply company.
• The electrical contractor should submit his test report and
completion certificate in required forms for consumer meter and
permanent electric supply connections to the buildings.

59. Execution

60. Execution
• Electric Services for Multi-storied Buildings
• The electrical distribution cables wiring should be laid in a separate duct. The duct should be
sealed at every alternate floor with non-combustible materials having the same fire resistance as
that of the duct.
• Water mains, telephone lines, intercom lines, gas pipe lines should be laid in the duct of cables
• Separate circuits for water pumps, lifts, staircase and corridor lighting and blower for the
pressurize system should be provided from the main switch gear panel.
• The inspection panel doors and any other openings in the shaft should be provided with air tight
fire doors having a fire resistance of not less than two hours.
• Medium and low voltage wiring running in shafts, and within a false ceilings, should run in metal
conduits.
• An independent and well ventilated service room should be provided on the ground floor.
• PVC cables should have an additional sheathing or protection provided by compound sprayed on
after installation

61. Staircase & Corridor lighting
• The following provisions have been recommended under the
development control regulations.
• The staircase and corridor lighting should be on separate circuit and
should be independently connected so that they could be operated by
one switch installations.
• Stair case and corridor lighting should also be connected to alternate
supply as defined in sub regulation.
• Emergency lights should be provided in the staircase/Corridor for
multi-storied special buildings.

62. Staircase & Corridor lighting

63. Alternate Source of Electric Supply
• A stand-by electric generator should be installed to supply power
to staircase and corridor lighting circuits, fire lifts, the standby fire
pumps, smoke extraction & damper systems in case of failure of
normal electric supply.
• The generator should be capable of taking starting current offal
machines and circuit s stated above simultaneously. If the stand-by
pump is driven by diesel engine. The generator supply need not to
be connected to the standby pump.

64. Alternate Source of Electric Supply

65. Distribution board
• A distribution board (also known as panel-board or
breaker panel) is a component of an electricity supply
system which divides an electrical power feed into
subsidiary circuits, while providing a protective fuse
or circuit breaker for each circuit in a common
enclosure.

66. Distribution Board

67. Transformers
•A transformer can accept energy at one
voltage and deliver it at another voltage. This
permits electrical energy to be generated at
relatively low voltages and transmitted at high
voltages and low currents, thus reducing line
losses and voltage drop

68. Transformers

69. Location of Transformer
• Location of the transformer is very important as far as
distribution loss is concerned. Transformer receives HT
voltage from the grid and steps it down to the required
voltage.
• Transformers should be placed close to the load centre,
considering other features like optimization needs for
centralized control, operational flexibility etc. This will
bring down the distribution loss in cables.

70. Types of Transformers
• Transformers are classified as two categories: power
transformers and distribution transformers.
• Power transformers are used in transmission network of
higher voltages, deployed for step-up and step down
transformer application (400 kV, 200 kV, 110 kV, 66 kV,
33kV)
• Distribution transformers are used for lower voltage
distribution networks as a means to end user connectivity.
(11kV, 6.6 kV,3.3 kV, 440V, 230V)

71. Sub-Station
Substation is a part of an electrical generation, transmission,
and distribution system, where voltage is transformed from
high to low, or low to high, or many other important
functions.
Electric power may flow through several substations between generating
plant and consumer, and may be changed in voltage in several steps.
Mainly Sub-station is defined as “The assembly of
apparatus used to same some characteristics (e.g. Voltage, AC to
DC, P.F. , Frequency etc.) of electric supply is called
Substation.”

72. Sub-station Layout
A:Primary power lines' side
1.Primary power lines
2.Ground wire
3.Overhead lines
4.Transformer for measurement of electric
voltage
5.Disconnect switch
6.Circuit breaker
7.Current transformer
8.Lightning arrester
B: Secondary power lines' side
7.Current transformer
8.Lightning arrester
9.Main transformer
10.Control building
11.Security fence
12.Secondary power lines

73. The Electric Act 2003
• The electricity act 2003, seeks to bring about a qualitative
transformation of the electricity sector through a new paradigm.
The act seeks to create liberal framework of development for the
power sector by distancing government from regulations.
• The objectives of the act are to consolidate the laws relating to
generation, distribution trading and use of electricity and generally
for taking measures conductive to development of electricity to all
areas, nationalization of electricity tariff, ensuring transparent
policies regarding subsidies, promotion of efficient and
environmentally benign policies, constitution of Central Electricity
Authority, Regulatory Commissions and established of Appeallate
Tribunal and for matter connected thereafter or incidental thereto”.

74. The Electric Act 2003
• The salient features of this act
• The central Govt to prepare a National Electricity Policy in Consultation with State
Govt.+
• Thrust to complete the rural electrification and provide for management of rural
distribution by Panchayats, Cooperative Societies, non-government organizations,
franchises etc.
• Provision for license free generation and distribution in the rural areas.
• Provision for private licenses in transmission and entry in distribution through an
independent network.
• The state Electricity Regulatory Commission is a mandatory requirement.
• Metering of all electricity supplied made mandatory.
• Provisions relating to theft of electricity made more stringent.
• Provisions safeguarding consumer interests.

75. References
Building Services: S.M. Patil
Internet Websites

76. Thanks..