ELECTRICAL INSTALLATIONS
Grp 1: aadhar, aum, kushik, gauri, insha, janhvi, sania
(sem : IV)
WIRING SYSTEMS
Submitted by: sania(19/AR/16)
What is Electrical wiring system ?
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Electrical wiring is generally refers to
insulated conductor used to carry
current and associated device.
Domestic electrical appliances like
lights, fans, washing machines, water
pump, etc are connected to the supply
through insulated wires which are
controlled by switches.
This wiring diagram gives the
connections of different appliances to
the supply within a house or building.
TYPES OF WIRING
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Cleat wiring
Wood casing wiring
CTS wiring or TRS wiring or Batten wiring
Conduit wiring
Metal sheathed wiring or lead sheathed wiring
CLEAT WIRING
WOODEN CASING WIRING
CTS wiring or TRS wiring
CONDUIT WIRING
METAL SHEATHED WIRING OR LEAD SHEATHED
WIRING
OPEN WIRING
CONCEALED WIRING
CIRCUITS
ADHAR TYAGI(19/AR/01)
CIRCUITS
A closed circuit is a complete electric circuit that
allows electrons to flow along an uninterrupted
path.
Electrons will only flow if the circuit is complete with
no gaps
SIMPLE CIRCUIT
Here is a simple electric circuit. It has a cell, a lamp and a switch.
To make the circuit, these components are connected together with
metal connecting wires. cell lamp switch wires
TYPES OF CIRCUIT
Devices within a circuit can be connected in one
of two ways:
● Series
● Parallel
Series circuit
Devices form a single pathway for electrons to flow
Parallel circuit
Devices form branches, each of which is a
separate path for the flow of electrons
Wiring diagram
A wiring diagram is a simple visual representation of the
physical connections and physical layout of an electrical
system or circuit. It shows how the electrical wires are
interconnected and can also show where fixtures and
components may be connected to the system.
Wiring diagram representation
Load capacity
The term "electrical load capacity" refers to the total
amount of power provided by the main source of
electricity for use by your home's branch circuits and
the lights, outlets, and appliances connected to them.
Load calculation
Calculating how much power your home needs is a matter of calculating the
amperage load of all the various appliances and fixtures, then building in a margin of
safety. Generally, it's recommended that the load never exceeds 80 percent of the
electrical service's capacity.
To use the math, you need to understand the relationship between watts, volts, and
amps. These three common electrical terms have a mathematical relationship that
can be expressed in a couple of different ways:
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Volts x Amps = Watts
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Amps = Watts/ volts
These formulas can be used to calculate the capacity and loads of individual circuits,
as well as for the entire electrical service. For example, a 20-amp, 120-volt branch
circuit has a total capacity of 2,400 watts (20 amps x 120 volts).
Wiring material & Lighting accessory :
Wire & Cable, materials ,types, main switch
Submitted by:
Kushik Mishra (19/AR/08)
Types of wire used in wiring
Vulcanized Rubber wire
A Vulcanised Rubber wire mainly
consists of a tinned conductor having
rubber coating.Tinning of conductor
prevents the sticking of rubber to the
conductor.Thickness of rubber mainly
depends on the operating voltage to
which wire is designed.A cotton
bradding is done over the rubber
insulations to protect the conductor
against the moisture. Finally the wire is
finished with wax for cleanliness.
Weather proof wire
•It made waterproof by
drooping it into waterproof
compound
•It is useful for service
connection
Lead covered wire
•No effect of moisture on it
•It used where there is
moisture presence.
Mineral insulated copper covered
•Less effect of temperature.
•Copper sheath is provided.
•It is used in mines, factory, refinery,
furnace, boiler, rolling,mill etc.
•Coating of magnesium oxide is
provided.
Poly Vinyl Chloride wire
•Dielectric strength is more
•Mechanical strength is more
•Life is long
•Protect against flame
•Protect against oil, alkali
•PVC wire is widely used
Lighting Accessory
INCANDESCENT LIGHT
FLUORESCENT LIGHT
LED DISCHARGE LIGHT
PENDANT LIGHTS
ISLAND POOL TABLE LIGHTS
HALOGENS
CHANDELIERS
CEILING MEDALLIONS
SCONES
FLUSH MOUNT LIGHTS
SEMI FLUSH MOUNT LIGHTS
TRACK LIGHTING
MAIN SWITCH
MAIN SWITCH : This switch is used
to switch “ON or OFF” the main
supply . These switches are used
to control the whole supply for a
house , office and machine . In
single phase circuit I.C.D.P main
switches are used, whereas in
three phase circuits I.C.T.P. main
switches are used to control the
supply.
Design consideration of
electric installation Protection against overload,short circuit and earth fault
By Gauri Patra, 19/AR/004
Types of loads
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Domestic Purpose
The electricity for domestic purpose is consumed in various types of loads such as:
(1)Single phase 5 A domestic Lighting load: -For lighting Filament lamps , fluorescent tubes , fans.
(2)Single phase 15 A power domestic load: -In case of air conditioning , electric water heating , refrigeration.
(3)Commercial load: (i)Shops (ii)Offices (iii)Schools (iv)Colleges
(4)Street light load : This is under Gram-Panchayat ;Municipality or corporation . A separate line is provided for this purpose
and is charged in a different type of tariff.
(5)Agricultural load :This is generally 3 phase 440 volts ,pumping motor load
(6)Rice mills /Sawmills : For this a 3 phase 440 volt 3-phase service line is separately provided.
(7)Industrial load: (a)For small scale industries / workshops (b)For medium scale industries (c)Large scale industries
Electric supply system
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250 V or less : LV
251 V to 650 V : MV
651 V to 33 kV : HV
Above 33 kV : EHV
DISTRIBUTION SYSTEM
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Single phase ac supply using a 2 – wire system;
Three phase ac supply using 3 – wire system;
Supply of Three phase and neutral using a 4 wire system.
DC SUPPLY
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A two wire system at 220 V
A three wire system with 440V between the two outer conductors and 220V between the outer conductors and
the centre wire.
Supply voltage
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Single phase : 240 V, 50 Hz, 2 wire
Three phase : 415V , 50Hz, 4 wire
Consumers with load requirement more than 250 kVA are provided with supply at high voltage with a substation
installed in the consumer's premises where voltage is stepped down to 415/240 V
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In India and many European countries the frequency of the supply is 50 Hz
In USA 60 Hz
VOLTAGE TOLERANCES
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Current carried by the electrical power distribution network varies at different times of the day.
It leads to varying voltage drops in the supply cables.
Under IE Rules voltage fluctuations may not vary by more than 5 % above or below the declared nominal voltage ,
frequency 1% from 50 Hz
Conductors and cables
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All conductor must me surrounded by insulators
In overhead the air act as insulation. Insulation requirement at supports through which lines are suspended from the ground
The conductor with insulation- A Cable
Mostly used insulation in cables are
– Paper (earliest material, works as good insulator as long as it is kept dry)
- Rubber ( from 1910 to 1950)
- Plastics ( most common PVC)
For cables for withstanding high temperatures we use silicon- rubbers
STRANDED CONDUCTORS
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Stranded conductor consist of no of Cu or Al wires place together like a rope.
Stranding is employed to make the cable flexible Stranded conductor is expressed as 3/.029, 7/.026 etc first no.represent no.of
strands and second no gives the diameter of each strand in inch or mm.
Parts of a conductor
Rating of cables
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Cables are always assigned a rating.
For rubber and plastic insulated cables rating is based on the temperature which the insulation can withstand.
When several plastic insulated cables run together in the same duct or conduit, rating may be reduced since
each will tend to heat each other .
CRITERIA FOR SELECTING CABLE
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It should be able to carry maximum expected current without the insulation getting damaged.
Voltage drop inside the cable should be permissible.
VOLTAGE DROP
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Depends on current , cross sectional area of the cable, and its length.
Voltage drop between supply point in any building and any outlet should not be more than 2.5% of the nominal
voltage.
PROTECTION OF ELECTRIC INSTALLATIONS AGAINST OVERLOAD, SHORT
CIRCUIT AND EARTH FAULT
Basic considerations
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There should be ready means of isolation of a circuit in the event of any accident or for the purpose of servicing. This is provided by
means of switches.
Conductors used should have adequate size. ie. Cross sectional area so that the current they will carry will produce minimum heat
and voltage drop.
Protection should be provided against excess current and electric shock.
Excess Currents
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Rated current for a wire is that value of current which does not cause the temperature of the wire to reach a value which would
damage the insulation.
Any value of current which causes the insulation to be damaged is called excess current or overload current.
The wire size selected according to a certain expected load.
If the load exceeds this value, system will draw the excess current.
Value of current depends on the extend of overload
Causes of overloads and short circuits
Causes of overloads
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By switching on heating or light loads of higher power rating.
By switching on a large no of heating or lights than what the wiring designed for.
Mechanical overloading of motors.
Mechanical faults in the motor.
Due to large friction at bearings & Jamming of rotor.
Short circuits
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When two phase wires or phase wire to neutral wire make direct contact.
Fuses are used to prevent damage, fire.
Earth fault
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When the phase wire makes contact with earth or any conducting material which is earthed, a short circuit exist
between the wire and earth called earth fault
Fuses are used to interrupt large current caused by earth fault.
Fuses and circuit breakers
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When the excess current is very high the operating time is very short.
When the excess current is small the operating time is longer
When short circuit occurs the resulting current will be extremely high and its flow should be arrested in shortest
possible time
When extra load is switched on which may draw say 25% higher than the rated current.
This current will not cause any immediate damage, the protective device should act after a time lag.
Topic 7 - Method Of Earthing, Fuse, Types Of Fuse,
Guidance For Installation Of Light And Fitting
By Janhvi Singh (19/AR/06)
EARTHING
Earthing or grounding is the process of transferring the immediate discharge
of electricity directly to the earth plate, by means of low resistance electrical
cables or wires. The electrical earthing is done by connecting the non-current
carrying part of the equipment or neutral of supply system to the ground.
The earthing is essential because of the following reasons:•The earthing protects the personnel from the shortcircuit current.
•The earthing provides the easiest path to the flow of shortcircuit current even
after the failure of the insulation.
•The earthing protects the apparatus and personnel from the high voltage
surges and lightning discharge.
METHODS OF EARTHING
1) PLATE EARTHING
In plate earthing system, a plate made up
of either copper with dimensions 60cm x
60cm x 3.18mm (i.e. 2ft x 2ft x 1/8 in) or
galvanized iron (GI) of dimensions 60cm x
60cm x 6.35 mm (2ft x 2ft x ¼ in) is buried
vertical in the earth (earth pit) which should
not be less than 3m (10ft) from the ground
level.
For proper earthing system, follow the
above mentioned steps in the (Earth Plate
introduction) to maintain the moisture
condition around the earth electrode or
earth plate.
2) PIPE EARTHING
A galvanized steel and a perforated pipe of
approved length and diameter is placed
vertically in a wet soil in this kind of system of
earthing. It is the most common system of
earthing.
The size of pipe to use depends on the
magnitude of current and the type of soil. The
dimension of the pipe is usually 40mm (1.5in) in
diameter and 2.75m (9ft) in length for ordinary
soil or greater for dry and rocky soil. The
moisture of the soil will determine the length of
the pipe to be buried but usually it should be
4.75m (15.5ft).
3) ROD EARTHING
it is the same method as
pipe earthing. A copper rod
of 12.5mm (1/2 inch)
diameter or 16mm (0.6in)
diameter of galvanized steel
or hollow section 25mm
(1inch) of GI pipe of length
above 2.5m (8.2 ft) are
buried upright in the earth
manually or with the help of
a pneumatic hammer. The
length of embedded
electrodes in the soil
reduces earth resistance to
a desired value.
4) EARTHING THROUGH THE
WATERMAN
In this method of earthing, the
waterman (Galvanized GI) pipes are
used for earthing purpose. Make sure
to check the resistance of GI pipes
and use earthing clamps to minimize
the resistance for proper earthing
connection.
If stranded conductor is used as earth
wire, then clean the end of the strands
of the wire and make sure it is in the
straight and parallel position which is
possible then to connect tightly to the
waterman pipe.
5) STRIP OR WIRE EARTHING:
In this method of earthing, strip
electrodes of cross-section not less than
25mm x 1.6mm (1in x 0.06in) is buried in
a horizontal trenches of a minimum
depth of 0.5m. If copper with a
cross-section of 25mm x 4mm (1in x
0.15in) is used and a dimension of
3.0mm2 if it’s a galvanized iron or steel.
If at all round conductors are used, their
cross-section area should not be too
small, say less than 6.0mm2 if it’s a
galvanized iron or steel. The length of
the conductor buried in the ground would
give a sufficient earth resistance and this
length should not be less than 15m.
FUSE
In electronics and electrical engineering, a
fuse is an electrical safety device that
operates to provide overcurrent protection of
an electrical circuit. Its essential component
is a metal wire or strip that melts when too
much current flows through it, thereby
stopping or interrupting the current. It is a
sacrificial device; once a fuse has operated it
is an open circuit, and must be replaced or
rewired, depending on its type.
Working Principle: Melting Of Internal
Conductor Due To Heat Generated By
Excessive Current Flow.
TYPES OF FUSE
The fuses are mainly classified into two types, depends on the input supply voltages they are the AC fuses
and the DC fuses.
DC Fuse
The DC fuse opens or breaks the circuit when the excessive current flow through it. The only
difficulty with the DC fuse is that the arc produced by the direct current is very difficult to extinct
because there are no zero current flows in the circuit. For reducing the DC fuse arcing the
electrodes are placed more distance apart due to which the size of the fuse increases as
compared to AC fuse.
AC Fuses
The AC fuses are categorised into two types they are the low voltage fuses and the high
voltage fuses. The frequency of the AC fuses changes it amplitude from 0º to 60º in very one
second. Thus, the arc extinction in the AC circuit can be done easily as compared to the DC
circuit.
The low voltage fuses can be further divided into four classes
shown below in the image Semi-enclosed or rewirable type
and totally enclosed, or cartridge type switches are the most
commonly used switches.
1) Rewirable Fuses
This type of circuit is mostly used in the small current circuit or for
domestic wiring. The fuse case and the fuse carrier are the two main
parts of the rewirable fuse. The base of the fuse is made up of
porcelain, and it holds the wires which may be made up of lead, tinned
copper, aluminium or alloy of tin-lead. The fuse carrier can be easily
inserted or taken out in the base without opening the main switch.
2) Totally Enclosed or Cartridge Type Fuses
The fuse element is totally enclosed in an enclosed container, and it
has metal contacts on both sides. These fuses are further classified as
D-type cartridge fuses and the Link type cartridge fuses.
2.1) D-Type Cartridge Fuses
The main parts of the D-type fuse are the base, adapter ring, cartridge and a fuse cap. The cartridge is kept in the
fuse cap, and the fuse cap is fixed to the fuse base. The cartridge tip touches the conductor when it is completely
screwed to the base and thus completes the circuit through the fuse links.
2.2) Link Type Cartridge or High Rupturing Capacity
In such type of fuses, the fuse element carries the fault current for a long duration. If the fault is not clear, then the
fuse element will melt and open the circuit. The major advantage of HRC fuse is that it clears the low as well as a
high fault current.
HRC fuse has the high-speed operation and also does not require maintenance. But the fuse element of the HRC
fuses needs to be replaced after each operation, and it also produced the heat during the faults which will affect
the operations of the nearby switches.
The enclosure of the HRC fuse is filled with powdered pure quartz, which acts as an arc extinction medium. The
silver and copper wire is used for making the fuse wire. The fuse wire has two or more sections which are joint by
using tin-joint. The tin-joint reduces the temperature under overloaded condition.
For increasing the breaking capacity of the fuses two or more silver wire is joined in parallel with each other.
These wires are adjusted in such a way so that only one wire will melt at a time. The HRC fuse is of two types
In knife blade type switches the fuse wire is replaced with a live circuit
with the help of fuse puller.The bolted type HRC fuses have two
conducting plates which are bolted to the fuse base. This fuse requires
the additional circuit for taking out the switch without getting a shock.
3) Dropout Fuse
The melting of fuse causes the fuse element to drop out under gravity
about its lower support. Such type of fuse is used for the protection of outdoor transformers.
4). Striker Fuse
It is a mechanical device having enough force and displacement which can be used for closing
tripping/indicator circuits.
5) Switch Fuse
Such type of switches is used for low and medium voltages circuit. The rating of the fuse unit
is in the range of 30, 60, 100, 200, 400, 600, and 800 amperes. The fuse unit is available as
3-pole and 4-pole unit. The making capacity of such type of fuses is up to 46 kA. They can
safely break depending upon rating currents of the order of 3 times the load current.
High Voltage HRC Fuses
The main problem of the high voltage fuses is that of the corona.
Therefore the high voltage fuses have the special design. They are
mainly classified into three types.
1) Cartridge Type HV HRC Fuse
The fuse element of the HRC fuse is wound in the shape of the
helix which avoids the corona effect at the higher voltages. It has two fused elements placed parallel with each
other, one of low resistance and the other is of high resistance. The low resistance wire carries the normal current
which is blown out and reducing the short circuit current during the fault condition.
2) Liquid Type HV HRC Fuse
Such type of fuses is filled with carbon tetrachloride and sealed at both the ends of the caps. When the fault
occurs then the current, exceed beyond the permissible limit, and the fuse element is blown out. The liquid of the
fuse acts as an arc extinguishing medium for the HRC fuses.They may be employed for the transformer protection
and the backup protection to the circuit breaker.
3) Expulsion Type HV Fuse
Expulsion type fuses are widely used for the protection of feeders and transformer because of their low cost. It is
developed for 11kV, and their rupturing capacity is up to 250 MVA. Such type of fuses comprises a hollow
open-ended tube made of synthetic resin-bonded paper.
The fuse elements are placed in the tubes, and the ends of the tubes are connected to suitable fittings at each
end. The arc producing is blown off in the inner coating of the tube, and the gases thus formed extinguish the arc.
G U I DAN C E F O R I N S TALLAT I O N O F L
IGHT AND FITTING
PLANNING THE PROJECT
1) Check your local wiring codes and schedule inspections.
2) Decide what type of fixture will work best in the area you’re trying to illuminate.
3) Decide what kind of bulb you want for your fixture.
4) Determine voltage and current requirements for the fixture.
5) Locate a suitable power source.
6) Plan the wiring route.
INSTALLING THE FIXTURE
1) Cut openings for the wiring.
2) Install the wiring.
3) Make sure your wiring is up to code.
4) Connect the devices that matches your application.