Electrical services of bs by krt

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Sub.: BUILDING SERVICES [3360604]
Prepared By:
K.R.THANKI
(BE Civil)
LECTURER CIVIL ENGINEERING DEPARTMENT
GOVERNMENT POLY TECHNIC ,
JUNAGADH,GUJARAT-INDIA.

CONTENTS:
Introduction
Different terminologies related to Electric Circuits
Direct and Alternating Current
Technical terms related to wiring
Electrical Accessories
Types of wires based on Insulation
Systems of Wiring
Indian Standard Recommendations for house wiring
Wiring Estimation
Maintenance of electric system in a building
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Introduction :
Electrical services is an mode which provides us the
electricity that is required by us to run electrical
appliances, in industries to provide electricity to run
the machineries , in commercial places to run the
mechanical services.
Use of electricity:
Residential Building: Lights , Fans, Heaters,
Television, Refrigerators etc.
Industrial Buildings: Machineries, Welding,
Electroplating etc.
Commercial Buildings: Lifts, Escalators, Alarm
Systems, Advertising Displays etc.

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Electricity is energy
transported by
the motion of electrons
**We do not make electricity, we
CONVERT other energy sources into
electrical energy**
What is Electricity?

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Faraday Effect
• Faraday Effect
• Basic Concepts
• Voltage – V – Potential to Move Charge (volts)
• Current – I – Charge Movement (amperes or amps)
• Resistance – R – V = IxR (R in =ohms)
• Power – P = IxV = I2xR (watts)

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How Does a Generator Work?

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Energy Transmission and Distribution:

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Electric current: The electric current means the
flow of electrons from one end of a conductor to
another end. Its symbol is ‘I’. And its unit is ampere.
Current (I) = Q/t = Ampere
Ampere: When charge of 1 coulomb passes
through a point in 1 seconds, it is said that a current
of 1 Ampere is flowing.
Ampere= Coulomb/Second

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Potential Difference: Work/energy Required to be
done to move unit charge from one point to
another in the circuit is called voltage or potential
difference
Voltage or Potential Difference= W/Q =
Work/Charge.
Conductors: Material which allow the current to
flow easily through them are called Conductors.
Insulator: Material which greatly oppose the
current flow i.e. do not allow the current to pass
through it are called Insulators.

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Electromotive force emf :
Energy required to move charge is known as EMF.
 It is denoted and measured in volts.
It is generally defined as the electrical potential for
a source in a circuit. A device that supplies electrical
energy is called electromotive force or emf.

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Resistance : Resistance is the opposition that a
substance offers to the flow of electric current.
 It is represented by the uppercase letter R. The
standard unit of resistance is the ohm, sometimes
written out as a word, and sometimes symbolized
by the uppercase Greek letter omega: Ω
The resistance (R) of an object is defined as the ratio
of voltage across it (V) to current through it (I).

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Specific resistance :
The electrical resistance offered by unit length and
unit cross section of a material when a known
voltage is applied at its ends.
Mathematically
where P is specific resistance.

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Conductance:
It is inverse to the Resistance.
It is defined as Ratio of Current to voltage. And it is
denoted as G.
 Unit of Conductance is mho. And denoted as
SI unit of Conductance is siemens “S”
The conductance of a resistor with a resistance of
five ohms, for example, is (5 Ω)−1, which is equal to
200 mS(mili siemens).

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 Conductor:
It is an object or type of material that allows the
flow of an electrical current in one or more
directions. A metal wire is a common electrical
conductor.
 Semiconductors:
These are crystalline or amorphous solids with
distinct electrical characteristics. They are of
high resistance — higher than typical resistance
materials, but still of much lower resistance
than insulators.

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 Insulator:
It is a material whose internal electric charges do
not flow freely, and therefore make it nearly
impossible to conduct an electric current.
A perfect insulator does not exist, because even
insulators contain small numbers of mobile charges
which can carry current.
Some materials such as glass, paper and Teflon ,
which have high resistivity, are very good electrical
insulators.

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Direct and Alternating Current:
• Direct Current:
• In DC , the direction of current does not change, but the
magnitude of the current may increase or decrease.
• The voltage cannot be changed easily
• Direct current cannot be transmitted at long distance.

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Direct and Alternating Current:
• Alternating Current :
• In AC, the magnitude and direction both changes with time
• The voltage can be changed easily
• Alternating Current can be transmitted along long distance

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Technical terms related to wiring :
• Domestic electric Supply:
The power is supplied to the houses in two different phases
depending upon the need of electricity. First is single phase
supply having 240 volts current at 50hz and
other is three phase supply having a voltage 420/240 volts at
50hz.
Single phase supply consists of two wires Live wire (red) and
Neutral Wire (black)
Three phase supply consists of 4 wires three live wires and
one neutral wire.

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• Domestic electric Supply:

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• Fuse: Fuse is a thin piece of wire with low melting point
connected at its end in a fuse plug. The function of fuse
wire is to protect the electrical appliances from heavy
current.
• It also known as cut out.
Types of Fuse
Rewirable Fuses
(Semi Enclosed)
Cartridge Fuse
(Totally enclosed)

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• Rewirable Fuses :
• This kind of fuse is most commonly used in the case of
domestic wiring and small scale usage. Another name for
this type is the KIT-KAT type fuse. The main composition is
of a porcelain base which holds the wires.
• These are cheaper and normally in circuits 15 A fuse is
used.
• Fuse always connect with Live Phase.
• The main metals or alloys used in making fuse wire include
lead, tinned copper, aluminum or tin lead alloy.

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Rewirable Fuses (Semi Enclosed)

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Totally Enclosed or Cartridge Type :
• In this type of fuse, we have a completely closed container
and there are contacts (metal) on either side.
Cartridge Fuse (Totally enclosed)

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• Miniature Circuit Breaker:
MCB is a device that is used to break the circuit at the time
of excess of current and protects the device from the
appliances from the damage.

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Characteristics
Rated current not more than 100 A.
Thermal or thermal-magnetic operation.

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The MCB has some advantages compared to fuse.
It automatically switches off the electrical circuit during
abnormal condition of the network means in over load
condition as well as faulty condition. The fuse does not
sense but miniature circuit breaker does it in more reliable
way. MCB is much more sensitive to over current than fuse.
Quick restoration of supply can not be possible in case of
fuse as because fuses have to be Rewirable or replaced for
restoring the supply. But in the case of MCB, quick
restoration is possible by just switching on operation.
Handling MCB is more electrically safe than fuse. Because
of to many advantages of MCB over fuse units, in modern
low voltage electrical network, miniature circuit breaker is
mostly used instead of backdated fuse unit.

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• ELCB: Earth Leakage Circuit Breaker is an device is
which breaks the circuit when there is leakage of the
current in the system.
There are two types of ELCBs:
1. Voltage Earth Leakage Circuit Breaker (voltage-ELCB)
2. Current Earth Leakage Circuit Breaker (Current-ELCB).

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Characteristics
Phase (line), Neutral and Earth
wire connected through ELCB.
ELCB is working based on Earth
leakage current.
Operating Time of ELCB:
The safest limit of Current which
Human Body can withstand is
30ma sec.
Suppose Human Body Resistance
is 500Ω and Voltage to ground is
230 Volt.
The Body current will be
500/230=460mA.
Hence ELCB must be operated
in 30maSec/460mA = 0.65msec

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• RCCB: Residual Current Circuit Breaker is a circuit
breaker that breaks the circuit when there is imbalance of
current between the live and the neutral wire this
imbalance can be due to the current leakage.

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• Cables :
Electrical cables are used to connect two or more devices,
enabling the transfer of electrical signals or power from one
device to the other.

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•What is Earthing?
Earthing is used to protect us from an electrical shock.
It does this by providing a path for a fault current to flow to
earth.
It also cause the protective devices to switch off the
electric current to the circuit that has the fault by help of
fuse.

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•Objectives of earthing :
Ensure that all exposed conductive parts do not reach a
dangerous potential
Provide an alternative path for the fault current to flow so
that it will not endanger the user from electric shock
To protect the building machinery and appliances from short
circuit.

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•Types of earthing:
Wire earthing
Rod earthing
Pipe earthing
Plate earthing

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•Conventional
Earthing
The Conventional system of
Earthing calls for digging of a
large pit into which a GI pipe or
a copper plate is positioned in
the middle layers of charcoal
and salt.
It requires maintenance and
pouring of water at regular
interval.

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Wire earthing:
In wire earthing is usually adopted in the rocky terrain. In this
method copper wire of enough length is buried in a trench

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Rod Earthing:
In this type of earthing a G.I. rod of 20mm diameter is
buried to a depth of 200 to 300 cm to this rod the earthing
wire is clamped.

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Pipe Earthing:
In this method pipe of 38mm diameter and 2m long is used
as an earth electrode. A hole of about 30cm diameter and
3.5m deep is dug into the ground using auger. The pipe is
placed in the hole the pipe covered with 80mm of charcoal
and a layer of common salt of 30mm to decrease the
resistance offered by the earth mass.

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Technical terms related to wiring :PIPE EARTHING

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PlateEarthing
In this method a G.I. plate or a copper plate is used as an
earth electrode. If a G.I. plate is used then a size of 0.3 x 0.3
with 6.35mm thickness should be adopted and if a copper
plate is used plate of 0.3m x0.3m and 3.20mm thick should
be adopted.
The plate is buried to a depth of 2.0m into the ground and
the plate is completely covered with a 80mm thick layer of
charcoal and 30mm thick layer of common salt

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Technical terms related to wiring :PLATE EARTHING

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Electrical Accessories :
Switch:
A switch is an electrical component that can break
an electrical circuit, interrupting the current or diverting it
from one conductor to another. The mechanism of a switch
may be operated directly by a human operator to control a
circuit (for example, a light switch or a keyboard button)

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One way switching
Figure shows how a lamp is controlled by a simple one-way
switch, providing on / off control of the lamp.

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Two way switching:
Figure shows how a lamp is controlled by a simple Two-way

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Two way switching:
Figure shows how a lamp is controlled by a simple Two-way

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Push-Button :
A push-button (also spelled pushbutton) or simply button is a
simple switch mechanism for controlling some aspect of
a machine or a process. Buttons are typically made out of
hard material, usually plastic or metal. The surface is usually
flat or shaped to accommodate the human finger or hand, so
as to be easily depressed or pushed.

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Pull switch :
A pull switch is a switch that is actuated by
means of a chain or string. An electric pull switch
is attached to a toggle type switch: one pull to
switch on and next pull to switch off.
The most common use of a pull switch is to
operate a ceiling electric light. The ceiling fan and
mechanical wall fans are also appliances often
operated by pull switches. Pull switches may be
either two-position (open or closed) or multi-
position (allowing for different fan speeds or
levels of illumination).

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Lamp holders :
Light bulb sockets, lamp sockets or lamp holders provide
electrical connections to the lamps and support it in the
lighting fixture. The use of sockets allows lamps to be safely
and conveniently replaced (re-lamping).

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Types of lamp
holders
According to
holding
pattern
Bayonet cap
lamp holder
Adison type
lamp holder
Goliath type
lamp holder
According to
mounting
pattern
Batten
holder
Pendent
holder
Angle
holder
Bracket
Holder

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According to holding pattern Electrical Accessories :
Bayonet cap lamp holder
BC lamp holders are normally found in domestic installations.
They are also available with a long shieldBC lampholders are
normally found in domestic installations.
They are also available with a long shield. The shield, which is
screwed on, is also used to retain any lampshade, which may
be fitted. The shield, which is screwed on, is also used to
retain any lampshade, which may be fitted.

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According to mounting pattern Electrical Accessories :
Batten Lampholders
Figure illustrates a straight batten lampholder fitted with a
‘short shield’. This shield provides protection against
touching of the lamp cap. The batten lampholder has no
backplate and therefore cannot be mounted directly on a
surface without the use of a suitable base or box. Batten
lampholders may have two or three terminals present.
A mounting block for use with batten lampholders
where necessary.

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Ceiling Roses
There are basically two types of ceiling rose available,
although there is a wide range of makes and shapes.
The two types are the Two-Plate Ceiling Rose, which has two
terminals and the Three-Plate Ceiling Rose, which has three
terminals.
Both were developed for use on different wiring systems.
Older types of ceiling roses were developed at a time when it
was not necessary to provide an earth at lighting points.

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Ceiling Roses
It is now essential to provide an earth,
and so an earth
terminal is now included on all ceiling
roses. This in effect means that a Two-
Plate Ceiling Rose has a third terminal
fitted, while a Three-Plate Ceiling Rose
has four terminals.
Figure illustrates one of the original
types of Two-Plate Ceiling Rose. The
earth terminal is marked “E” and the
two unmarked terminals are used for
the neutral and the switch wire. There
must also be a cord grip provided
similar to that in a lampholder.

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Ceiling Roses wiring diagram :

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Adopter
Adopter is used to power supply to small instruments .
It is generally made of backalite material with two contacts.
Connector:
It generally use to connect relay and timers; with tube light
and fans.
Distribution board :
When there are two or more wiring system is connected to
circuits then Distribution board is used. 15 A fuse is
connected with every circuit with distribution board

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Socket Outlets:
Socket outlets are fixed to switch board. It consists socket
base with two or three terminals. One sleeve is connected
with phase[P] and other is with neutral [N] and one is
connected to Earthling[E].
Plug:
Plug is used to gain power from socket outlet and connect
the circuits of instrument.
There is two types of plugs :
Two pin plugs : it consists Brass pins one is phase and other is
Neutral.
Three pin plugs: It consists three brass pins ; two small phase
and one is neutral.
These plugs normally of 5A and 15 A.

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Mounting Blocks:
Mounting blocks are generally circular or square of wood or
PVC.
It provides insulated base to celling, lampholders or switches.
Main switch:
It generally provided near to main electric meter. It is used
to control building electric system.
It also known as Iron Clad Switch due to insulation of iron is
provided to this switch.
Type of Main switch :
Double pole Iron clad Switch: Used to connection of single
phase.
Triple pole Iron clad switch: Used to connection of three
phase.

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Types of wiring Based on insulation:
vulcanized Indian rubber wire (V.I.R)
Tough rubber sheathed wire or Cab Tyre Sheathed(T.R.S)
Poly Vinyl Chloride wire (P.V.C.)
Lead Covered Wire
weather proof wires
Flexible wire
MICC wire (Mineral Insulated Copper Covered Wire)

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V.I.R (Vulcanised Indian Rubber)
wires.
 It is called vulcanized insulation rubber wire.
Copper & aluminum conductor and rubber coating
are used in it. Now single & double braided wires
are mostly in a use. But it has lower tensile strength,
chemical reaction & bad insulation so it is not used.
 suitable for: low & medium voltage supply only
 old type: not readily available to purchase

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T.R.S. (Tough Rubber Sheathed)
wires.
 This type of wire is a modification of V.I.R. wire. It
consist of the ordinary rubber coated conductors
with an additional sheath of tough rubber.
 This layer provides better protection against
moisture and wear and tear. Also it provides an extra
insulation.
 These wires are generally available in single
conductor, two conductors or three conductors.
 It is called crab tyre sheath wire & tuff rubber sheath
wire. Hard & good rubber coating on copper wire is
used in this wire. Its used in house wiring & industrial
wiring.
 Available in 250/440V only

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T.R.S. (Tough Rubber Sheathed)
wires.

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Weather proof wire:
No weather reaction , in this types of wire.
Because it has cotton breeding with water proof. But
it is flammable so no in use now.

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LC wire:
It is called lead covered wire. Lead pipe on
rubber insulation & its coating on conductor. It is very
good in moisture condition but less tensile strength so
low uses now.

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MICC wire :
It is called mineral insulated copper covered wire. In
this type wire copper conductor coated is with
magnesium oxide. And After copper coating is coated
on it. In case of moisture weather PVC coating
(serving) is coated on its. It is uses in mines, factory,
furnace, boiler, rolling mills etc. magnesium oxide is
used for avoiding moisture problems.

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6. PVC wire:
It is called poly vinyl chloride wire. PVC coating on copper
conductor so its so many advantages as follows.
(a) High dielectric strength
(b) High tensile strength
(c) More defense against moisture
(d) High life
(e) No disturb in vibration
Available in 600, 660, 1100 Voltage, Widely used Long life
Durable against water, heat, oil, UV light

Flexible wires.
These wires consists of number of strands
instead of a single conductor. (Strand is a very
thin conductor).
The conductor is insulated with P.V.C.
material.
These wires are very useful for household
portable appliances where flexibility of wire is
more important.
Typical specifications
55/.01mm(55 strands of 0.1mm diameter),
maximum current 6A,used for household
purposes.
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Types of Wiring Systems:
Cleat Wiring
CTS Wiring or TRS Wiring or Batten Wiring
Metal sheathed wiring or lead sheathed
wiring
Casing and Capping
Conduit Wiring

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Cleat Wiring
Insulated conductors are supported on or wooden
cleats. The cleats have two halves one base and the
other cap. The cables are placed in the grooves
provided in the base and then the cap is placed.
Both are fixed securely on the walls by long screws.
This wiring is suitable for temporary installations
where cost is the main criteria.

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Cleat Wiring

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Cleat Wiring
Advantages :
Easy installation.
Materials can be retrieved for reuse.
Flexibility provided for inspection, modifications and
expansion.
Relatively economical.
Skilled manpower not required.

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Cleat Wiring
Disadvantages :
Appearance is not good.
Open system of wiring requiring regular cleaning.
Higher risk of mechanical injury.

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Batten Wiring Types of Wiring Systems:
Wires sheathed in tough rubber are used which are
quite flexible.
Clipped on wooden battens with brass clips and
fixed on to the walls by flat head screws.
Moisture and chemical proof. Suitable for damp
climate but not suitable for outdoor use in sunlight.
Suitable for lightning in low voltage installations

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Cab Rubber Seth Wire or Tuff Rubber Seth Wire

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Advantages :
Easy installation and is durable.
Lower risk of short circuit.
Cheaper than casing and capping system of wiring.
Gives a good appearance if properly erected.

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Disadvantages :
Danger of mechanical injury.
Danger of fire hazard.
Should not be exposed to direct sunlight.
Skilled workmen are required.

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Metal Sheathed
Similar to CTS but the are individually insulated and
covered with a common outer lead-aluminum alloy
sheath.
The sheath protects the cable against dampness,
atmospheric extremities and mechanical damages.
Earthed at every junction to provide a path to
ground for the leakage current.
The wiring system is very expensive. It is suitable
for low voltage installations.

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Metal Sheathed

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Metal Sheathed
Precautions to be taken during installation:
The clips used to fix the cables on battens should
not react with the sheath.
Lead sheath should be properly earthed to prevent
shocks due to leakage currents.
Cables should not be run in damp places and in
areas where chemicals (may react with the lead)
are used.

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Metal Sheathed

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Metal Sheathed
Advantages :
Easy installation and is aesthetic in appearance.
Highly durable.
Suitable in adverse climatic conditions provided the
joints are not exposed.

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Metal Sheathed
Disadvantages :
Requires skilled labor.
Very expensive.
Unsuitable for chemical industries.

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Casing and Capping
Insulated conductors laid inside PVC boxes having
grooves inside.
A rectangular strip of wood called capping having
same width as that of casing is fixed over it.
Both the casing and the capping are screwed
together at every 15 cms. Casing is attached to the
wall.
Two or more wires of same polarity are drawn
through different grooves. The system is suitable for
indoor and domestic installations.

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Casing and Capping

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Casing and Capping
Advantages :
Cheaper than lead sheathed and conduit wiring.
Provides good isolation as the conductors are placed
apart reducing the risk of short circuit.
Easily accessible for inspection and repairs.
Since the wires are not exposed to atmosphere,
insulation is less affected by dust, dirt and climatic
variations.

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Casing and Capping
Disadvantages :
Highly inflammable.
Usage of unseasoned wood gets damaged by
termites.
Skilled workmanship required.

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Conduit Wiring
Cables run through PVC pipes providing good
protection against mechanical injury and fire due to
short circuit.
Embedded inside the walls or supported over the
walls, and are known as concealed wiring or surface
conduit wiring (open conduit) respectively.
The system is best suited for public buildings,
industries and workshops.

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Conduit Wiring

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Conduit Wiring
Advantages :
No risk of fire and good protection against
mechanical injury.
The lead and return wires can be carried in the same
tube.
Earthing and continuity is assured.
Waterproof and trouble shooting is easy.
Shock- proof with proper earthing and bonding
Durable and maintenance free
Aesthetic in appearance

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Conduit Wiring
Disadvantages :
Very expensive system of wiring.
Requires good skilled workmanship.
Erection is quiet complicated and is time consuming.
Risk of short circuit under wet conditions (due to
condensation of water in tubes).

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Factors Affecting The Choice Of Wiring
System:
The choice of wiring system for a particular
installation depends on technical factors and
economic viability.
1.Durability: Type of wiring selected should conform
to standard specifications, so that it is durable i.e.
without being affected by the weather conditions,
fumes etc.
2.Safety: The wiring must provide safety against
leakage, shock and fire hazards for the operating
personnel.

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Factors Affecting The Choice Of Wiring
System:
3.Appearance: Electrical wiring should give an
aesthetic appeal to the interiors.
4.Cost: It should not be prohibitively expensive.
5.Accessibility: The switches and plug points
provided should be easily accessible. There must be
provision for further extension of the wiring system,
if necessary.
6.Maintenance Cost: The maintenance cost should
be a minimum
7.Mechanical safety: The wiring must be protected
against any mechanical damage

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