UNIVERSITY SCHOOL OF PLANNING AND ARCHITECTURE

GURU GOBIND SINGH INDRAPRASTHA UNIVERSITY

ENERGY SYSTEMS,

ELECTRICITY AND

FIRE SAFETY

[COURSE CODE AP 312]

UNIVERSITY SCHOOL OF PLANNING AND ARCHITECTURE

ENERGY SYSTEMS, ELECTRICITY AND FIRE SAFETY (AP 312)

LIST OF CONTENTS

Unit 1: Energy Systems and Electricity

1. Chapter 1: Basic Energy Systems and Sources

2. Chapter 2: Basic Concepts of Electricity and Electrical Transmission

3. Chapter 3: Distribution System: Wiring and Switches.

4. Chapter 4: Current Protective Devices and Methods

5. Chapter 5: Transformers and Polyphase Circuits

6. Chapter 6: Captive Power Generation and Backup Supply

7. Chapter 7: Electrical Substations and their Planning

8. Chapter 8: Integrated Electrical Data and Electrical Plans.

Some important terms related to Electricity

Assignment

Unit 2: Fire Safety

1. Chapter 1: Introduction to Basics of Fire

2. Chapter 2: Fire Detection Systems: Types

3. Chapter 3: Fire Resistant Construction and Planning

4. Chapter 4: Design Guidelines for Fire Safety

5. Chapter 5: Fire Suppression Systems and Smoke Control

Assignment

Appendix I: National Electric Code

Appendix II: Electrical Plans

Appendix III: Nation Building Code for Fire Safety

CHAPTER 1: BASIC CONCEPTS OF ENERGY SOURCES

[1.1] Renewable and Non-renewable Sources of Energy

1. Renewable Sources of Energy: Renewable energy is energy that comes from natural

resources such as sunlight, wind, rain, tides, waves and geothermal heat. Also called non-

conventional sources of energy.

2. Non-renewable Sources of Energy: are the sources of energy which cannot be reproduced,

grown, generated, or used on a scale which can sustain its consumption rate like fossil

fuels-coal and petroleum; and radioactive fuels. Also called Conventional sources of

energy since they are being used since a long time.

[1.2] Some Important Renewable Sources of Energy

a) Hydro-electricity

b) Wind Power

c) Solar Energy

d) Geothermal Energy

e) Nuclear Energy

f) Biogas and Biomass

g) Tidal and Wave Energy

h) Thermal Power Generation

[1.2.1] Hydro-electricity

1. What is Hydro-electricity?

Hydroelectricity refers to electricity generated by hydropower; the production of

electrical power through the use of the gravitational force of falling or flowing water.

2. Mechanism: Hydro-electric Power Plant:

A typical hydro-electric power plant is a system that has three main parts:

(i) Reservoir: where water can be stored.

(ii) Dam: with gates to control water flow.

(iii) Power Plant: where the electricity is produced.

Hydro-electric power plant uses the force of flowing water to produce electricity: a

dam opens gates at the top to allow water from the reservoir to flow down through

tubes called penstocks and the fast-moving water spins the blades of turbines.

The turbines are attached to generators to produce electricity: the waters force on

the turbine blades turns the rotor, the moving part of the electric generator. When

coils of wire on the rotor sweep past the generators stationary coil, electricity is

produced which is transported along transmission lines to a utility company.

There are two types of turbines that can be used:

(i) Reaction Turbine: is a horizontal or vertical wheel that operates with the

wheel completely submerged, a feature which reduces turbulence.

(ii) Impulse Turbine: is a horizontal or vertical wheel that uses the kinetic energy

of water striking its buckets or blades to cause rotation.

3. Advantages:

(i) Energy Storage: Biggest advantages of hydro-electric power dams are their ability

to store energy: the water in the reservoir has potential gravitational energy.

(ii) Clean Source: It is a clean and environmental friendly source of energy as it does

not produce any kind of pollution.

(iii) Renewable: It is a renewable source of energy as the water can be replenished by

the Water Cycle.

(iv) Cheaper: Hydropower is cheaper than electricity from coal or nuclear plants

because the fuel-flowing water is free to use.

(v) Flexible: Hydro is a flexible source of electricity since plants can be ramped up

and down very quickly to adapt to changing energy demands.

4. Disadvantages:

(i) Building of dams is a very high cost project.

(ii) Building of dams can cause huge geological damage triggering earthquakes.

(iii) Dams may also lead to floods in some cases.

(iv) Dams also disturb the water table due to digging of deep trenches.

5. Efficiency: The larger the dam, the better is the efficiency of hydroelectricity. Smaller

dams generally have smaller turbines, and the intensity of the flow of water is also not

consistent, so they have a lower efficiency.

[1.2.2] Wind Power

1. What is Wind Power?

Wind power is the conversion of wind energy into a useful form of energy, such as

using wind turbines to make electrical power or windmills for mechanical power.

2. Mechanism: Wind Power Plant:

In a wind power plant the most important component is the wind turbine or the wind

mill that comprises of large fan blades which are connected to the hub which is

mounted on a shaft.

When the atmospheric wind blows over the fan blades they start rotating, due to

which the shaft also starts rotating; but since the speed of rotation of the shaft is very

slow & not sufficient to produce the electricity, the shaft is connected to the gear box.

The high speed output shaft is connected to the generator and it rotates inside the

generator which produces electricity ready for transmission. Amount of energy which

the wind transfers to the rotor depends upon the density of air, rotor area and the

wind speed.

The type of turbines used are:

(i) Small Turbines: to produce electricity less than 10 kW (for homes).

(ii) Intermediate Turbines: to produce electricity from 10-500 kW.

(iii) Large Turbines: for producing distributive electricity larger than 500 kW

3. Advantages:

a) Clean Source: It produces no air pollution or carbon emissions.

b) Renewable: It is a renewable source of energy as wind will never finish.

c) Cost: Low operational Cost.

d) All Day Energy: It blows throughout the day-electricity can be produced whole day.

4. Disadvantages:

a) It has high capital costs (although low operating cost).

b) It depends on wind velocity which may decline due to climate change.

c) It poses danger to birds and aerial wildlife.

d) Noise is also an issue at some of the wind farms.

5. Efficiency: the value or efficiency of a wind turbine/wind mill or wind farm depends upon

its location (wind zone), terrain and wind speed. Wind speed increases with height above

the ground. Wind Power Equation: P = p x A x V3 (P Wind Power, A - Area swept

by rotor, V Wind Velocity).

[1.2.3] Solar Energy

1. Active and Passive Solar Energy:

(i) Active solar: techniques include the use of photovoltaic panels and solar

thermal collectors to harness the energy.

(ii) Passive solar: techniques include orienting a building to the Sun, selecting

materials with favourable thermal mass or light dispersing properties, and

designing spaces that naturally circulate air.

2. Solar Cell and Solar Panels (Mechanism):

A solar cell is an electrical device that converts the energy of light directly into

electricity by the photovoltaic effect: It is a form of photo-electric cell which, when

exposed to light, can generate and support an electric current without being attached

to any external voltage source.

A solar panel is a packaged, connected assembly of photovoltaic cells. The solar

panel can be used as a component of a larger photovoltaic system to generate and

supply electricity in commercial and residential applications.

The solar cell/panel works in three steps:

(a) Photons in sunlight hit the solar panel and are absorbed by semiconducting materials,

such as silicon.

(b) Electrons are knocked loose from their atoms, causing an electric potential

difference: Current starts flowing through the material to cancel the potential and this

electricity is captured.

(c) An array of solar cells converts solar energy into a usable amount of direct

current (DC) electricity.

3. Advantages:

a) Clean: No greenhouse emissions and pollution.

b) Renewable: available in plenty all throughout the day.

c) Cost: Solar energy costs nothing- it is practically free.

d) Maintaince: Solar cells do not require much maintenance.

e) No Noise: they produce no noise unlike any other energy sources.

4. Disadvantages:

a) Initial cost of the equipment used to harness the sun energy is high.

b) A solar energy installation requires a large area for greater efficiency.

c) Solar energy is only useful when the sun is shining and not at night.

d) Location of solar panels affects performance due to possible obstructions.

5. Some Commonly used Solar Devices:

(i) Solar Lantern

(ii) Solar Cooker

(iii) Solar Air Heater

(iv) Solar Water Heaters

(v) Solar Street/Landscape Lighting

(vi) Solar Car and Rickshaws

(vii) Solar Watches and Calculators

[1.2.4] Geothermal Energy

1. What is Geothermal Energy?

Geothermal energy is heat energy generated and stored in earth. It is the energy that

determines the temperature of matter.

2. Different Sources of Geothermal Energy:

(i) Hot Water Reservoirs: these are reservoirs of hot underground water which is

more suited for space heating than for electricity production.

(ii) Natural Stem Reservoirs: In this case a hole dug into the ground can cause steam

to come to the surface.

(iii) Geo-pressured Reservoirs: In this type of reserve, brine completely saturated

with natural gas in stored under pressure from the weight of overlying rock.

3. Use Mechanism:

(a) It can be used directly by sending water down a well to be heated by the Earths

warmth, extracting it using a pump and then injecting it back into the earth

(appropriate for sources below 150o C)

(b) It can be used to produce electricity by rotating the blades of a turbine using hot

water or steam and dry steam power plants.

4. Advantages:

a) Useful minerals, such as zinc and silica, can be extracted from underground water.

b) It is renewable as the earths heat will never deplete or decrease with time.

c) It does not require a very large plot of land (400 m2 is sufficient).

5. Disadvantages:

a) Drilling of holes can cause noise pollution.

b) Brine can salinate soil if the water is not injected back into the reserve.

c) Extracting large amounts of water can lead to an increase in seismic activity.

d) Power plants that do not inject the cooled water back into the ground can release H2S,

the gas with the smell of rotten egg.

[1.2.5] Nuclear Energy

1. What is nuclear energy?

Nuclear energy is the energy of an atomic nucleus, which can be released by fusion or

fission or radioactive decay. Nuclear power is the use of sustained nuclear fission to

generate heat and electricity.

2. Mechanism: Nuclear Power Plant:

Nuclear reactor produces and controls the release of energy from splitting the atoms

of elements such as uranium and plutonium: the energy released from continuous

fission of the atoms in the fuel as heat is used to make steam.

The steam is used to drive the turbines which produce electricity (as in most fossil

fuel plants) but without the combustion of fossil fuels and resultant greenhouse gas

emissions.

3. Disadvantages:

a) High cost of installation, operation, maintaince and waste disposal.

b) Nuclear power plants use large quantities of water.

c) It produces dangerous and contaminating wastes.

[1.2.6] Biogas and Biomass

1. What is Biogas?

It is a fuel which is produced from the breakdown of organic matter: anaerobic

digestion of organic material like Animal Manure, Sewage Sludge, Industrial Waste,

Household Waste, Energy Crops etc. abundantly available in the countryside.

It is a mixture of about 60 % methane & 40 % CO2.

2. Mechanism: Biogas Plant:

3. Applications:

a) Cooking: Biogas can be used in a specially designed burner for cooking purpose.

b) Lighting: Biogas is used in silk mantle lamps for lighting purpose.

c) Power Generation: Biogas can be used to operate a dual fuel engine.

d) Transport Fuel: After removal of CO2, H2S and water vapour, biogas can be

converted to natural gas quality for use in vehicles.

4. Advantages:

a) Better and cheaper fuel for cooking, lighting and power generation.

b) Produces good quality enriched manure to improve soil fertility.

c) Effective and convenient way for sanitary disposal of human excreta.

d) As a smokeless domestic fuel it reduces the incidence of eye and lung diseases.

5. Disadvantages:

a) Number and kind of animals to be served.

b) Location of the system and Collection and transportation of inputs.

c) Temperature maintenance and Handling of outputs.

[1.2.7] Wave and Tidal Energy

1. What are Tidal and Wave Energies?

Tides are generated through a combination of forces exerted by the gravitational pull of

the sun, moon and the rotation of the earth. Tidal/ wave power is a form

of hydropower that converts the energy of tides into useful forms of power - mainly

electricity. Wave power (depends on height, speed, length and density of water wave) is

distinct from Tidal power in that tidal power fluctuates daily.

2. Mechanism: Energy can be extracted from tides by creating a reservoir or basin behind a

barrage and then passing tidal waters through turbines in the barrage to generate

electricity, ready for transmission.

3. Advantages:

a) Clean: It is environment friendly and doesn't produce greenhouse gases.

b) Renewable: It is an inexhaustible source of energy and highly efficient.

c) No Fuel: It does not require any fuel to run.

d) Longer Life: Life of Tidal Power plant is very long.

e) Predictable: we can predict the rise and fall of tides.

4. Disadvantages:

a) It influences aquatic life adversely.

b) Cost of construction of tidal power plant is high.

c) This transmission is expensive and difficult from coastal regions.

[1.2.8] Thermal Power Generation

1. What is Thermal Power?

Thermal power is the power obtained from heat is generated in a Thermal power station.

2. Mechanism: Thermal Power Station:

A thermal power station is a power plant in which water is heated and converted into

steam. The steam spins a steam turbine which drives an electrical generator.

After it passes through the turbine, the steam is condensed in a condenser and

recycled to where it was heated.

3. Advantages:

a) The fuel used is quite cheap and cost or generation less.

b) Less initial cost as compared to other generating plants.

c) It can be installed at any place irrespective of the existence of coal.

d) Its Installation requires less space as compared to Hydro power plants.

4. Disadvantages:

a) It pollutes the atmosphere due to production of large amount of smoke and fumes.

b) It is costlier in running cost as compared to Hydro electric plants.

CHAPTER 2: BASIC CONCEPTS OF ELECTRICITY

TYPES OF CURRENT AND ELECTRICAL TRANSMISSION

[2.1] Conductors and Insulators

Replacement of valence electrons (apparent movement) quickly among atoms of

materials produces electricity. On the basis of this there are two types of materials.

1. Conductors: A material or element that allows free movement of electrons and

therefore allows easy flow of electricity. Most metals are conductors-eg. Cu, Al, Ag.

Conductor implies that the outer electrons of the atoms are loosely bound and free to

move through the material thus conducting electricity. Conductors have less no. of

valence electrons.

Types of conducting wires: light wire (low current), power wire (high current), cables

(very high current for transmission).

2. Insulators: A material that does not easily transmit electrical energy through it or

have high resistance to the flow of charge through them is called Insulators. Materials

like, wood, rubber and ceramics are considered insulators. Most non-metals are also

insulators. The outer electrons of the atoms such materials are tightly bound and

hence show resistance to move opt freely. Insulators have large number of valence

electrons.

Wherever there is a conductor, there has to be an insulator to prevent the flow of electric

energy to any conductive material that touches the conductor. Thats why a conductive

wire, say of copper, is insulated by say a sheathed rubber.

[2.2] Alternating Current and Direct Current

1. Alternating Current (AC): is an electric current that reverses its direction periodically

many times in a second at regular intervals (repetition). The frequency of repetition of

this current is 60 Hertz- means the direction of the current changes sixty times every

second. It is typically used in domestic and industrial power supplies through power lines

and transmission towers. Single Phase and Three Phase supply:

(i) Single Phase Supply: is the distribution of AC electrical power where all the

voltages of the supply vary in unison. This supply has one or two live wires, one

neutral wire, and essentially one ground/earth wire. Essentially used for Lighting

and heating systems at 220 volts.

(ii) Three Phase Supply: AC supply that consists of three AC voltages 120 out of

phase with each other. This supply has three live wires, may or may not have a

neutral but definitely has a ground wire. Used for high power electrical appliances

at 440 volts.

2. Direct Current (DC): is an electric current that flows in one direction only. Batteries are a

good source of DC. A DC circuit consists of any combination of constant voltage sources,

constant current sources, and resistors. DC is used to charge batteries & electronic

devices and very large quantities of DC power are used in

production electrochemical processes. High voltage DC is used to transmit large amounts

of power from remote generation sites or to interconnect alternating current power grids.

[2.3] Short Circuit and Electric Shocks

1. Short Circuit: is a fault in a circuit, when a live conductor comes in direct contact with a

another live conductor, by breakdown of insulation to provide a path of least resistance

which causes a very high current to flow that overheats the installation and eventually

burns the electric cables causing fire. It might be a result of selecting a wire of wrong

rating. This wrong selection may also lead to underperformance of wire.

2. Electric Shock: Electric shock occurs upon contact of a (human) body part with any

source of electricity that causes a sufficient current (flowing electrons) through the skin,

muscles, or hair. Remember, electric shock occurs because of transfer of energy and not

mass of electrons.

[2.4] Electricity/Electric Power Transmission

Electric-power transmission is the bulk transfer of electrical energy (as per demand), from

generating power plants to electrical substations located near demand centres through

various transmission lines making a transmission network or grid:-

1. Generation at Power Plant: electricity (three phase AC) is produced at a high voltage

of 25000 V by the generators at the power plant.

2. Voltage Conversion for Transmission: this voltage is converted to a higher voltage- as

high as 275000-400000 V by a step up transformer at the power station.

3. Long Distance Transmission: electricity is transmitted at this very high voltage to

reduce the energy lost in long-distance transmission through overhead power lines

and transmission towers.

4. Voltage Conversion for Distribution: The high voltage supply is converted by

regional companies to lower voltages like 6600 V (by a step-down transformer) for

district supply and further reduced to a standard 415 V for local supply:

(i) For domestic purposes, connection for the consumer is made to provide a 240

V single phase supply.

(ii) For heavy industries, the connection is made for very high voltage three phase

supply: 250-500 kVA.

Limitation in the distribution of electric power: electrical energy cannot be stored, and

therefore must be generated as per needs and demands: and so a sophisticated control

system is required to ensure this demand-supply matching (If demand > Supply,

transmission is shut down).

National Grid: To reduce the risk of such failures, electric transmission networks are

interconnected into regional, national or continental wide networks thereby providing

multiple alternative routes for power to flow forming a power.

[2.5] Concept of Power Factor

The power factor of an AC electrical power system is defined as the ratio of the real

power (P) flowing to the load to the apparent power (S) in the circuit and is a

dimensionless number between 0 and 1.

Po

(i) Real power is the capacity of the circuit for performing work in a particular time.

(ii) Apparent power is the product of the current and voltage of the circuit.

In an electric power system, a load with a low power factor draws more current than a

load with a high power factor for the same amount of useful power transferred.

Power factor correction is an adjustment of the electrical circuit in order to change the

power factor to 1.When PF=1, phase angle (between voltage and current) =0 and the

reactive power Q=0, the efficiency of the circuit is optimal since all the supplied power is

used for work on the load. The power factor correction is usually done by adding

capacitors to the load circuit, since the circuit has inductive components, like electric

motor.

[2.6] Connected Load

It is the sum of the continuous power ratings (in watts) of all load-consuming apparatus

connected to an electric power distribution.

Example of Connected load Calculations: An apartment has 5 fan points of 60 watts each, 8

points for tube lights of 40 watt each, 3 points for down lights of 10 watt each and 2 power

points of 1.4 Kilo-watts each. Calculated the connected load of the circuit?

Solution:

Total load of fan points = 5 x 60 = 300 watts

Total load of tube light points = 8 x 40 = 320 watts

Total load of down light points = 3 x 10 = 30 watts

Total load of power points = 2 x 1400 = 2800 watts

Therefore, total connected load = 300 + 320 + 30 + 2800 watts

= 3450 watts or 3.450 kW

Power Factor = P/S

CHAPTER 3: ELECTRICITY DISTRIBUTION: WIRING & SWITCHES

[3.1] Distribution System: LT and HT Panels

The local wiring or cables between the high-voltage substations and customers is referred

to as electric power distribution.

This local wiring is of two types depending on the voltage to be carried which is different

for domestic purposes and heavy industries:

(i) Low Tension (LT) Cables: carry electricity at lower voltages.

(ii) High Tension (HT) Cables: carry electricity at higher voltages.

LT Distribution Panel: or LV (Low Voltage) panel is an electrical distribution and control

panel with fuses, disconnect switches and indicators for circuits running at a voltage

which is not dangerous to life i.e. less than 1000 volts (AC); on the low tension side of a

distribution transformer.

HT Distribution Panel: or HV (High Voltage) Panel is a electrical distribution panel

consisting of electrical disconnect switches, fuses or circuit breakers used to control,

protect and isolate electrical equipment and to provide high voltage current for operating

motors and high voltage electrical machines. It is placed on the high tension side of the

Distribution transformer and can carry voltages more than 1000 volts (AC).

[3.2] Distribution Board and Electric Meters

1. Distribution Board / Box

A distribution board is a component of an electricity supply system which divides

electrical power into subsidiary circuits through wiring systems, while providing a

main switch, a protective fuse or circuit breaker for each circuit.

A distribution board or box is made of a metal (usually, galvanised) for long life and

to make it fire-proof. The box is called a steel trunk.

On the outside are mounted MCBs or a main switch and the inside houses subsidiary

circuits and bus bars (for drawing current, usually made of copper). It also houses

power cables, light cables and signal cables.

Position: They are usually placed close to the entry point of the mains supply.

2. Electric Meter

An electric meter is a device that measures the amount of electric energy consumed

by a residence, business, or an electrically powered device.

Electric meters are calibrated kilowatt hour [kWh]- the most common billing unit:

periodic readings of electric meters establishes billing cycles and the energy used

during one cycle.

Position: Electrical meter boxes are usually installed at Ground Floor level or stilts

level for taking readings easily preferably in the recess of a wall for rain protection.

[3.3] Wiring Systems: Batten Wiring and Conduit Wiring

1. Batten System of Wiring:

This is an older system of wiring used for indoor installations; in which wires are run

through wooden battens made by teak wood: the wires are fixed to the wooden batten

through brass link clips and clamps and usually remain exposed.

These battens are then are fixed to the walls by flat head screw or wood plugs and

battens are coated by varnish to resist atmospheric reactions and for protection from

all insects and rodents.

Advantages: Batten wiring is very cheap and takes comparatively less time to install.

Also since the wires remain exposed, any problem in the wire can easily detected.

2. Conduits and Conduit Wiring:

Conduits are PVC or Metal (square or circular) sections used to run wires through

them unhindered in roofs, walls and floors for:

(i) Protection of wires form rodents and exposed weather conditions.

(ii) Providing a means of replacing and renewing wire cables easily.

For the installation of Conduits, chases or grooves are cut in wall and the conduits are

secured to the wall with metal clamps or clips. To obtain larger lengths, conduits are

joined together by couplers.

Disadvantage: fire due to short circuits remains undetected till exposed at some

external surface.

[3.4] Electrical Switches and Switch Boxes

A Switch is a device that can break an electrical circuit by interrupting the current. An

electrical switch has three parts:

(i) Box containing the switches with wires.

(ii) Front plate of the Switch (Base plate, Face plate and Cover Plate)

(iii) Mechanism controlling the Switch.

The number and types of switches (On-Off type, Push Button and Touch Button) should

match client requirements and electrical standards.

Function of a switch Box: Collection of all the electrical wires:

(a) It retains a clear cavity and maintains it for collection of wires.

(b) It is used for anchoring the switch plate.

Switch Box is made of metals like galvanised steel or PVC because it should not let the

civil work fall inside and should considerably fire-resistant.

The front plate is screwed to the switch box after the terminals of the plate have been

connected with the respective wiring or electrical cables.

Extra wiring is kept while planning electrical Layouts and Switch Outlets for

modification at switch level, for repair purposes or for workability in case of wires

becomes short or burnt.

Types of Plugs: Power Plug of 15 A (3 point) and Light Plug of 5 A (2 point).

[3.5] Types of Switches

1. Toggle Switch: they are actuated by a lever angled in one of two or more positions

2. Pushbutton Switch: Pushbutton switches are two-position devices actuated with a button

that is pressed and released.

3. Selector Switch: Selector switches are actuated with a rotary knob or lever of some sort to

select one of two or more positions.

4. Joystick switch: It is actuated by a lever free to move in more than one axis of motion.

5. Proximity Switch: they sense the approach of a metallic machine part either by a magnetic

or high-frequency electromagnetic field.

6. Pressure Switch: Gas or liquid pressure can be used to actuate a switch mechanism if that

pressure is applied to a piston, diaphragm, or bellows, which converts pressure to

mechanical force.

7. Dolly Switch: an electrical on-off switch whose external operating mechanism is a short

pivoted lever terminating in a rounded knob, rather than a spring-loaded rocker.

8. Rocker Switch: A rocker switch is a switch which consists of a piece which rocks back

and forth in response to pressure to open and close a circuit. Rocker switches are

commonly used as light switches

CHAPTER 4: CURRENT PROTECTIVE DEVICES AND METHODS

[4.1] Circuit Breakers, Fuses, MCB and ELCB

1. Circuit Breaker: is an over-current protective device that causes a break in the circuit in

the event of excess flow of current through a wire so as to protect it against damage by

overheating cased by the excess currents. Made for a specific rating of current & voltage.

2. Fuses: a fuse is a protective device that operates through a wire that is designed to

overheat and rupture at a pre-determined maximum current; to break the circuit. There are

three types of fuses:

(i) Semi-enclosed Rewirable Fuse: cheapest fuse available that consists of a porcelain

fuse folder with brass terminals. In case of rupture, the holder is pulled out and

replaced. Disadvantage: wire may oxidise overtime. Rating: 5, 10, 15 & 30 A.

(ii) Cartridge Fuse: in this, fuse wire is surrounded by closely packed granular filler

that absorbs the energy released due to rupture to avoid damage to the fuse carrier.

Advantage: easy to replace by pressing into place between terminals and does not

oxidise overtime. Rating: 2-15 A.

(iii) HBC Cartridge Fuse: high breaking capacity cartridge fuse are used for more

heavily loaded installations, it consists of a ceramic tube with brass end caps and a

silver element. The element is surrounded with granular silica filling to absorb

heat generated during rupture.

3. MCB: or Miniature Circuit Breakers have replaced conventional fuses as protective

devices in final circuits of buildings.

Mechanism:

The simplest miniature circuit breaker consist of a sealed tube with silicon fluid and a

closely fitted iron slug.

In case of overload the magnetic pull of the charged coil surrounding the tube cuases

the iron slug to move through the tube and trip the circuit breaker switch, which

closes without any damage.

To make the circuit one just has to open the switch.

Advantage: operation of a switch is all that is needed: nothing to be replaced as such.

4. ELCB: or Earth Leakage Circuit Breaker is a safety device used in electrical installations

with high earth impedance to prevent shock. It detects small stray voltages on the metal

enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is

detected.

Advantage: ELCBs are less sensitive to fault conditions that RCDs (residual current

devices), and therefore have fewer nuisance trips.

Disadvantage: ELCBs introduce additional resistance & an additional point of failure into

the earthing system.

[4.2] Earthing and Grounding

Contact with an electrically charged material or the exposed conductive surfaces of an

electrical device, transfers the charge through the body to the ground as human body is a

fairly good conductor; thus receiving an electric shock.

This hazard can be avoided by keeping the exposed conductive surfaces of the device at

earth potential by connecting one supply conductor to the earth or ground; because the

huge mass of earth is electrically neutral.

Usually, in most electrical installations, the exposed metal (conductive) surfaces are

connected to the earth through a copper conductor as a path of least resistance to the

discharge of electrical energy (rather than the human body) for the purpose of safety.

This is known as earthing or grounding- a process of providing protection against electric

shock by transferring the current to the earth.

[4.3] Lightening Arrestors

Lightning arrester is a device used in electrical installations to protect the wires and

electrical cables of the power system from the damaging effects of lightning.

Since lightning s tends to strike the highest object in the vicinity, the arrestor- a rod is

placed at the apex of a tall structure. The typical lightning arrester has a high-

voltage terminal and a ground terminal.

When a lightning surge travels along the power line to the arrester, the current from the

surge is diverted through the arrestor (a low resistance cable) to the earth as earth is

electrically neutral.

If protection fails or is absent, lightning that strikes the electrical system introduces

thousands of kilovolts that may damage the transmission lines, and can also cause severe

damage to transformers and other electrical or electronic devices.

[4.4] National Electric Code (NEC)

NEC is the benchmark for safe electrical design, installation, and inspection to protect

people and property from electrical hazards

The NEC addresses the installation of electrical conductors, equipment, and raceways;

signalling and communications conductors, equipment, and raceways; and optical fiber

cables and raceways in commercial, residential, and industrial occupancies.

CHAPTER 5: TRANSFORMERS AND POLYPHASE CIRCUITS

[5.1] Transformer

A transformer is an electrical device that transfers energy by inductive coupling between

two or more of its windings: It is typically used for AC-to-AC conversion of a single

power frequency in terms of voltage, essential for long distance transmission.

In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion

to the primary voltage (Vp) and is given by the ratio of the number of turns in the

secondary (Ns) to the number of turns in the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus enables an AC voltage to

be stepped up by making Ns greater than Np, or stepped down by making Ns less

than Np.

[5.2] Polyphase Circuits: Star and Delta Connection

Polyphase Circuits: They are a group of AC circuits having two or more interrelated

voltages, usually of equal amplitudes, phase differences, and periods, etc. Eg: Star and

Delta Connections.

Star and Delta Connection: It is a type of connection applied at the substation end of the

power supply transmission line in a step-down current transformer; in which the primary

coil is connected in star fashion while the secondary is connected in delta fashion as

shown:

Advantages of Star-Delta Connection:

1. The primary side is star connected and hence less number of turns are required: this

makes the connection economical for large high voltage step down power

transformers.

2. The neutral available on the primary can be earthed to avoid distortion.

Disadvantage of Star-Delta Connection: In this type of connection, the secondary

voltage is not in phase with the primary- there is s +30 Degree or -30 Degree Phase Shift

between Secondary Phase Voltage to Primary Phase Voltage. Hence it is not possible to

operate this connection in parallel with star-star or delta-delta connected transformer.

CHAPTER 6: CAPTIVE POWER AND GENERATION AND BACKUP SUPPLY

[6.1] Captive Power Generation: DG Sets

Electricity generation by a DG Set as a part of the in house power plant, independent of

the national power grid for emergency power supply or otherwise is called Captive Power

Generation.

A Diesel Generator (DG) Set is the combination of a diesel engine with an electrical

generator to generate electrical energy; that are used in places without connection to

the power grid as emergency purpose as well as for more complex applications.

Sizing of DG sets is critical to avoid low-load or a shortage of power. Size ranges:

(i) For Homes and Offices: 8 - 30 kVA (single phase)

(ii) For Factories and Industrial Generation: 11 - 25000 kVA (three phase)

[6.2] Power Inverters

It is an electrical power converter that converts DC to AC: the converted AC can be

obtained at any required voltage & frequency with the use of appropriate transformers

and control circuits; for backup power supply in case of emergency or the failure of the

main power supply.

An Inverter has no moving parts and is basically a high-power electronic oscillator that

converts the power from DC sources like batteries or solar panels into AC power supply

for small power supplies (like computers) as well as for high voltage bulk power supply.

It is so named because early mechanical AC to DC converters were made to work in

reverse, and thus were inverted, to convert DC to AC.

[6.3] UPS- Uninterruptable Power Source

An uninterruptible power source or battery backup is an electrical apparatus that provides

emergency power to a load when the input main power source fails.

A UPS differs from a power inverter as it provides near-instantaneous protection from

input power interruptions by supplying energy stored in batteries; but the on-battery

runtime of most UPS is relatively short (only a few minutes) but sufficient to start a

standby power source or properly shut down the protected equipment.

A UPS is typically used to protect computers, data centres and telecommunication

equipment, where an unexpected power disruption can cause serious data loss.

CHAPTER 7: ELECTRICAL SUBSTATIONS, ITS DESIGN & PLANNING

[7.1] Electrical Substation

An electrical substation also called a grid station is a subsidiary station for

the generation, transmission, and distribution of electrical power.

They transform voltage from high to low or the reverse: between the generating station

and consumer, electric power may flow through several substations at different voltage

levels: Collector Substation, Converter Substation, Transmission Substation, Distribution

Substation, Switching Substation

[7.2] Basic composition/elements of a substation

1. Incomer (11kV )

2. Distribution Panel

3. Transformer

4. Earthing/Grounding

5. Control Building

6. Circuit Breaker

7. Disconnect Switch

[7.3] Design and Planning of Substation

It is essential to properly design and carefully plan out the installation of an electrical

substation because a good design attempts to achieve sufficient reliability without excessive

cost. Various steps towards designing and planning a substation:

1. Criteria for Installation of Transformer.

2. Preparation of One line diagram.

3. Preparation of Plot Plan

4. Elevation Design of Substation.

5. Foundation Design of Substation.

6. Grounding and Fence Details.

7. Planning Implications of:

(i) The main substation

(ii) The Switch Rooms

(iii) The Battery Rooms

[7.3.1] Criteria for Installation of Transformer

1. Size and Capacity: Transformers have a certain Capacity and size. Based on the

requirement and the area, a transformer of a particular capacity is selected.

2. Type of Transformer: The type of transformer to be installed is another criteria: It can be-

Pole mounted, Kiosk type, Room type (closed) or Outdoor type (open).

3. Length of cables: minimum length of all cables and wiring should be considered.

4. Position of Incomer: Connection of incomer and substation should be kept in mind while

deciding location and orientation.

5. Building Structure: a transformer should be placed at a certain distance i.e. setback from

building structure. This setback can be used for plantations, parking, guard room (3 m2)

or meter room (1.2 m2). So the substation lies basically in the set back area.

6. Floor Level: A transformer is never installed in a basement because of difficulty in

accessibility, the risk of flooding and because bye-laws do not allow.

7. Backup Requirement: A substation has two supplies Line power supply and backup

supply. A separate generator system for backup should be connected to the line source but

a little away from the substation.

[7.3.2] Requirements of One Line Diagram:

1. Adequate numbers and location of Current Transformers, Primary and Secondary

Regulators, Circuit Breakers and Fuses.

2. Relative location and Rating of all surge arrestors (since all transformers are grounded).

3. Adequate protection for personnel via isolating and grounding switches.

4. Orientation and north point.

5. All present and future construction to be marked.

[7.3.3] Requirements of a Plot Plan

1. All access roads, culverts and other drainage surfaces.

2. Fence and gate locations.

3. Allowance for removal & installation of equipment and access maintaince.

4. Sufficient space for future expansion.

5. The entire area outside and inside fence (to an extent of 3 3 around the fence, there is a

4-6 inches filling of gravel to avoid spreading and percolation of water near substation).

[7.3.4] Elevation of Substation

1. Minimum clearance of 86 inches from grade level to lowest external point.

2. Overhang ground wire should be at an angle less than 45o, preferably 30o.

3. Surge arrestor length should be as short as possible.

[7.3.5] Foundation of Substation

1. Steel reinforcements bar size, spacing and locations to be specified.

2. Anchor bolt markings.

3. Cable trenches: outline reinforcements, gravel fill and cover.

[7.3.6] Grounding and Fence details

1. Minimum depth of earthing pit should be 18 inches.

2. For conductivity reasons, it has to remain wet; so it has to be recharged from time to time

for conductivity.

3. There are two ground pits- one for the transformer and one for the lightening arrestor.

4. Ground grade should extend minimum of 3 feet outside the fence (for substation.)

5. Ground conductor should be made of copper, copper clad steel or steel.

6. Fence / gate height should be 7 feet with a 1 feet barb wire extension.

[7.3.7.1] Planning implication of Substations:

1. All Enclosures must be accessible 24 hrs to authorised personnel only.

2. The access must provide 4 x 4 widths to height ratio.

3. All access roads must be provided for heavy trucks, mobile cranes etc; except when the

substation directly faces the street.

4. Two means of escape must be provided, with a door at each end.

5. All access/escape doors should be fire rated and the door cill should be atleast 75 mm

high (so that no oils spills out).

6. The incoming main to the building require easements 2 m wide underground and 7 m

wide over ground, for free passage of cables [Easements are gaps devoid of any

construction].

7. Do not provide any drain around or through the substation (atleast not before 1m from the

fence).

8. The upper level substation i.e. at a certain a height from ground; should have a dry type

transformer and not oil cool transformer.

9. Kiosk transformers require adequate foundations (cables should be deep enough).

10. The transformer is a noise creating equipment. So it should be placed selectively away

from a building or should have sufficient sound barriers.

[7.3.7.2] Planning implication of Switch Rooms:

It is a place or rather a room where meters, circuit panels etc are installed and it has switches,

fuses and circuit breakers. Planning Implications:

1. It should not be located more than one floor above or below the entry of a building.

(Reason: Ease of access and control)

2. It should not be located in fire isolated stairway and corridors or near fire sprinklers or

water tanks

3. It should be dry and adequately ventilated.

4. Distribution board must be readily accessible so that in case of emergency we can switch

on/off circuits and locate it such that distance between distribution panel and final sub-

circuit is not greater than 20 m.

5. The cables for electrical, fire, power, telephone and emergency lighting should run in

separate cable ducts or conduits.

[7.3.7.3] Planning implication of Battery Rooms:

It is a place or rather a room where all batteries are stacked up for emergency backup. It

should be dry and ventilated and care should be taken for noise control and fumes exhaust.

CHAPTER 8: INTEGRATED ELECTRICAL DATA

AND ELECTRICAL PLANS

[8.1] Stepwise Procedure for Data Integration

1. Estimate the total load in kVA.

2. Choose the type of Substation-

(i) Pole Mounted

(ii) Kiosk Type

(iii) Room Type

(iv) Outdoor Type

3. Estimate the space requirement for Substation, Switch room etc.

4. Integrate all electrical equipment inside the building.

[8.2] Estimation of load in kVA

Total kVA demand of a building depends on the area of the building. This means, Load

Factor = x kVA / m2. Estimated load Factors of some common buildings:

Building Type Load Factor in kVA

1. Non AC Home Block 15

2. Office Block 50

3. Computer Centre 200

4. Shopping Centre 70

5. Malls 100

6. Naturally Ventilated Car Parking 5

7. Mechanically Ventilated Parking 20

8. Non AC Cinema Halls and Libraries 50

9. AC Halls and Libraries 100

[8.3] Electrical Plans

For a given apartment layout, an electrical layout is made based on the requirements and

allocation of electrical fittings: It is a plan that coordinates all electrical in an

apartment/building.

The electrical layout is made with the standard symbols used for electrical firings and a

Loading Chart is made.

For any room the position of light fittings like fans, tube lights etc and power fittings like

AC, TV etc are decided on the base of furniture layout and the shortest wiring rote w.r.t to

distribution boards and junction boxes.

Example of Loading Chart for a one bedroom house unit:

S.N. Symbol Description Nos. Wattage Height from F.F.L.

1

1200 mm Dia

4

60

C.L.

2

Florescent Light

6

40

As per RCP

3

16 A MCB

1

-

Above S.L (100 mm)

4

Down lights

2

8

At LL

F.F.L Finished Floor Level

R.C.P Reflected Ceiling Plan

C.L Ceiling Level

L.L. Lintel Level

S.L Skirting Level

Refer: Appendix II

AC

SOME IMPORTANT TERMS RELATED TO ELECTRICITY

1. Alternator: a device used to generate AC by rotating conductors periodically through a

magnetic field.

2. Ambient Temperature: the temperature surrounding a device. Ambient temperature

needs to be maintained. Eg. In a computer rooms, LAN wires produce a lot of heat so it

has to be an air-conditioned room.

3. Ammeter: a device that measures the flow of current through a wire. It should have low

impedance and should be connected in series. Unit: ampere. 1A = 1C/1S.

4. Amplifier: device used to increase the intensity of a signal.

5. Ampacity: maximum current rating of a wire or device.

6. Amplitude: highest value reached by a signal current or voltage.

7. Attenuator: device used to decrease the amount of signal.

8. Branch Circuit: a circuit or portion of wiring system that extends beyond a circuit

protection device.

9. Capacitor: a device made of two conductive plates with a di-electric (insulator) in the

centre. It is a temporary charge holder.

10. Choke: is an inductor designed to present impedance to AC or to be used as a current

filter for DC power supply.

11. Circuit: a closed loop of conducting wires or current.

12. Compressor: a device used in refrigeration system to maintain a constant pre4ssure

between high and low sides.

13. Conduction Level: the point at which at a given voltage and current, the device shall

start passing the current.

14. Current Rating: amount of current flow that a device is designed to withstand.

15. Hybrid Circuit: Combination of series and parallel circuits. They are not used in power

circuits because power circuits require exact amount of current.

16. Ohms Law: Current is proportion to voltage and V = IR.

17. Ohmmeter: a device that measures the resistance of a wire. It does not require circuit,

power source but has a battery. Unit: Ohm.

18. Parallel Circuit: more than one path of current flow. Current in circuit is equal to the

sum of current flowing in individual paths or each component in parallel circuit has same

voltage drop or total resistance is reciprocal of the sum of reciprocals of individual

resistance: 1/R = 1/R1 + 1/R2 + 1.R3.

19. Resistance: is the obstruction in the flow of current. It is a function of the material of a

wire. It depends on area of cross-section (less area, more resistance), material of wire,

length of wire (more length, more resistance), and temperature (more temperature, more

resistance high temperature, more electrons bang with each other).

20. Series Circuit: current flow is same at any point in circuit or sum of voltage drops around

circuit must be equal to applied voltage. R = R1 + R2 + R3.

21. Voltage: force that pushes electrons through a wire.

22. Voltmeter: a device that measures voltage at any point in the circuit. It is direct

connected across a power source in series. Unit: Volt.

23. Watt: measure of amount of power used by circuit. P = VI or P = I2R.

ASSIGNMENT ON ELECTRICITY

1. Discuss any two renewable sources of energy with neat sketches. Also state their

advantages and disadvantages.

2. What is geothermal energy? What are its sources? How can it be harnessed? State its

merits and demerits? What is the cost of producing geothermal energy?

3. Which is the best energy renewable energy source and why? Draw a diagram to explain it

mechanism and state its merits and demerits.

4. Explain the working of solar panels in detail with a neat sketch.

5. Explain the following sources of energy with their advantages and disadvantages:

(i) Solar Energy (ii) Hydro-electricity (iii) Geothermal Energy (iv) Biomass

6. What is an electrical substation? What are its main elements? Enumerate the design and

planning implications & specifications of an electrical substation.

7. What are the functions of a switch and a fuse in an electrical system?

8. What is MCB? Fuses have been replaces by MCBs? Give reasons.

9. What is a transformer? How does it work? What arte its planning implications? Explain

the concept of Power Factor.

10. What is DG set? What is its purpose?

11. What are the various types of electrical switches available? What is rocker type and dolly

operated switches?

12. While planning a socket and switch box, a provision extra length of wire is made. Why?

13. Draw an electrical plan of a one bedroom apartment and prepare a loading chart for the

same, using standard symbols of fittings and appliances used.

14. A private guest house has two bedrooms, kitchen, bathroom, living room and a balcony. It

has 5 fan points, 30 watt each and 20 plug points of 100 watts each.

(i) Calculate the total connected load.

(ii) Calculate the total number of AC circuits.

(iii) Draw a single line diagram of the circuit.

15. Answer the following short answer questions:

a) Why are Hybrid circuits not used in power circuits?

b) Why do wire posses resistance? State the factors on which it depends.

c) Resistance of a wire increase with increase in temperature. Why?

d) Computer rooms need to be air conditioned. Give reason.

16. Write Short Notes on:

a) Conductors and Semiconductors

b) Electricity Transmission

c) Distribution of Electricity

d) Distribution Board

e) Earthing Systems

f) Conduit Wiring

g) Connected Loads

h) Lightening Arrestors

i) HT and LT Panels

j) AC and DC

CHAPTER 1: INTRODUCTION TO BASICS OF FIRE

[1.1] Triangle of Fire

The triangle of fire illustrates the three elements a fire needs to ignite: heat, fuel, and oxygen.

The fire will be prevented or extinguished by removing any one of the elements in the fire

triangle:

1. Heat: Without sufficient heat, a fire cannot begin, and it cannot continue.

2. Fuel (Combustible Materials): Without fuel, a fire will stop (fire can be caused because

of a Gas, Liquid, Carbon or even Electricity).

3. Oxygen: Without sufficient oxygen, oxidizer a fire cannot begin, and it cannot continue.

[1.2] Stages of Fire

1. Insipient stage: At this stage, fire just gets started and a spark is seen. Characterised

by: No visible smoke, no flame and very little heat. A significant amount of invisible

combustion particles may be created. This stage usually develops slowly.

2. Smoke/ Smouldering Stage: Hidden Smoke comes out. Characterised by: visible smoke,

but no flame and little heat.

3. Flame Stage: This is the beginning of a fully developed fire. Characterised by: visible

flame, more heat, often less or no smoke, particularly with flammable liquids and gas

fires. This stage demands the actuation of fire hydrants.

4. Heat Stage: This is the fully developed Fire. Characterised by: Large amounts of heat,

flame, smoke and toxic gases are produced. The transition from the previous stage can be

very fast. Only Multiple Hydrants can Control this fire.

[1.3] Methods of Spreading of Fire

1. Conduction: Generally, the movement of fire from one room to another is by direct touch

with the material s present.

2. Convection: Convection currents carry fire through shafts and vertical circulation areas

of buildings. Convection means through air.

3. Radiation: Heat Radiation from a building to an exposed surface can cause exposed

surface to disintegrate. Radiation means without physical touch.

[1.4] Fire Hazard

The major products combustion in a fire hazard are smoke and heat: while heat increases

the ambient temperature, smoke has catastrophic effects on occupants (causes

asphyxiation and toxification and eventually death). However, smoke does not damage

the building physically.

When a building is on fire, first attempt should be that fire doesnt spread or otherwise

prominence is given to human and animal life first, then to precious property and then to

Intellectual Property.

[1.5] Classification of Buildings based on Fire Hazards

1. High Hazard: Buildings that are extremely vulnerable to fires: Eg. Chemical factories,

Petroleum Plants, Natural Gas plants and shops selling electrical items.

2. Medium Hazard: Such buildings have low combustible material but protection system is

installed for safety. Eg. Offices, Schools and Colleges.

3. Low Hazard: Buildings with small chance of getting fire. Eg. Residential Building

CHAPTER 2: FIRE DETECTION SYSTEMS

[2.1] Types of Fire Detection Systems

A Fire Detection System is designed to detect the unwanted presence of fire by

monitoring environmental changes associated with combustion: smoke and heat.

Fire detection systems are based on these stages of fire. Early Detection of Fire saves

lives and therefore detection at insipient stage is the best.

[2.2] Smoke Detectors

A smoke detector is a device that detects smoke typically as an indicator of fire for early

warning of life safety either by optical detection (photoelectric type) or by physical

process (ionization type). Essentially, best detection system would be the combination of

both the types.

Smoke detectors are typically housed in a disk-shaped plastic enclosure about 150 mm in

diameter and 25 mm thick. In large commercial, industrial, and residential buildings they

are usually powered by a central fire alarm system, which is powered by the building

power with a battery backup.

[2.2.1] Ionisation Type Smoke Detector (Spot Type)

1. Condition of Use: Ionisation type smoke detection is a sensitive detection system used

when flaming fires are expected; used for early warning of life safety and for protection

of means of egress (escape).

2. Working Mechanism:

The system consists of a small radioactive source that emits ions (alpha particles)

inside an ionisation chamber that is open to air.

These ions move to the negative side of the electrodes in the chamber and allow the

passage of a small current between the electrodes by forming a small electrical

circuit.

If any smoke particles (from cigarette, paper etc) pass into the chamber the ions will

attach to the particles and reduce the amount of current. An electronic circuit detects

the current drop, and sounds the alarm.

3. Advantages:

It is cheaper and easier to manufacture.

It is very sensitive and even a small fire can be detected.

4. Disadvantages:

It is too sensitive: it is prone to false (nuisance) alarms since it can detect smoke

particles too small in size also.

They lose efficiency if installed at a ceiling height of more than 1.5 m.

[2.2.2] Photoelectric or Optical Type Smoke Detector

1. Condition of use: Photoelectric type of detection system is used when smouldering fires

are expected and is useful for large smoke particles like those emanating from PVC

particles.

2. Working Mechanism:

The system has a small light beam from a transmitter to a receiver station .In the

absence of smoke, the beam light passes in front of the detector in a straight line.

When smoke enters the optical chamber across the path of the light beam, some light

is scattered by the smoke particles (light intensity reduces), directing it at the sensor

and thus triggering the alarm.

3. Advantages:

They are quicker to sound in response to a slow smouldering fire.

They also are less likely to go off while cooking.

4. Disadvantages:

Less Sensitivity: It is tuned to a specific initial intensity of smoke.

The intensity of the smoke affecting the detector depends on the height of mounting

of detector: larger the height, lower is the intensity affecting.

5. Types of Photoelectric Smoke detectors:

(i) Photoelectric Spot Type: used for standard height ceilings.

(ii) Photoelectric Line Type: used in areas having high ceilings like Industrial

Buildings, Churches and Warehouses.

[2.3] Heat Detectors

A heat detector is a fire alarm device designed to respond when the convected thermal energy

of a fire increases the temperature of a heat sensitive element. Heat detectors have three main

classifications of operation:

1. Fixed Temperature Type: It is the most common type of heat detector; that includes a

bimetallic strip with a feasible link in between. It reaches its operating temperature after

the surrounding air temperature exceeds that fixed threshold temperature. It is

essentially used in closed rooms.

2. ROR (Rate of Rise) Type: These detectors are used in response to rapidly increasing

temperatures (caused by rapidly increasing fires), irrespective of the starting temperature

and have the electronic thermostat as a main component. As the rate of heat goes up, the

resistance of thermostat drops and the detector activates. It is used in areas having rise in

temperature and not in fluctuating ambient temperatures.

3. Rate Compensation Type: It is a sealed, more sensitive detector designed for dusty &

moist areas; used in enclosed areas and severe environments like historic monuments etc.

[2.4] Flame Detectors

A flame detector is a detector that uses optical sensors to detect flames at the flame stage of

fire. They are of Various Types:

(i) UV type

(ii) IR type

(iii)Thermocouple flame detectors.

(iv) Ionisation flame detectors (which use current flow in the flame to detect flame presence).

[2.5] Location of Fire Detectors

1. Detector locations are decided according to smoke and heat movements:

(i) Smoke has high kinetic energy and moves immediately to height of 6 m after which it

cools down and moves horizontally. At lower heights smoke fills up the ceiling.

(ii) Heat from fire moves vertically upwards and fills the space at the soffit of the slab.

2. Thus, the sensors or detectors are mounted at the bottom level of the slab. For a general

layout, a smoke detector can cover an area of 80 m2 from a farthest point of 6 m and heat

detectors can cover an area of 50 m2 from a farthest point of 5 m.

[2.6] Design Essentials for fire Detection Systems

1. Fire detection systems shall be self-contained, stand alone systems able to function

independently of other building systems.

2. Fire Detection systems shall not be integrated with other building systems such as

building automation, energy management, security, etc.

3. The type of detection systems depend on the protection goals of the owner and the type of

occupancy and materials to be protected.

4. All fire detection systems installed in buildings having a total occupant load of 500 or

more occupants shall be a voice/alarm communication system.

5. All fire detection system wiring shall be installed in rigid metal conduit. Stranded wiring

shall not be used.

CHAPTER 3: BUILDING SAFETY I: FIRE SAFETY STANDARDS-

CONSTRUCTION AND MATERIALS

[3.1] Fire Rated Door

A fire rated door means that the door can withstand a temperature 1000o C on side when

the temperature on the other side does not increase 40o C over the ambient temperature; to

provide insulation, stability and integrity.

(i) Insulation: temperature should not increase the above figures.

(ii) Stability: the door frame should withstand the temperature & should not char.

(iii) Integrity: there should be no development of minor cracks for fire to transfer from

one side to another.

Fire Rated Doors, used in escape staircases, boiler rooms, electrical rooms and kitchens;

are usually made of hardwood like teak, insulated with mineral wool and have smoke

seals on door jambs.

They can be rated 30 min, 60 min, 120 min etc, which is the time required for the fire to

spread as it requires an initial to spread.

[3.2] Fire Escape Staircase

1. What is a Fire Escape Staircase?

A fire escape is a special kind of emergency exit, usually mounted to the outside of

a building or occasionally inside but separate from the main areas of the building.

It provides a method of escape in the event of a fire or other emergency that makes

the stairwells inside a building inaccessible.

2. Design Guidelines for Fire Escape Staircase

a) Fire Rated Door: The Staircase should be equipped with a 120 minute rated fire entry

door and this door shall open into the staircase.

b) Widths and Dimensions: Fire escape staircase should be 1 m wide for residential

buildings, 1.5 m wide for hostels and educational buildings and 2 m wide for

hospitals and assembly buildings; and the tread should be 250-300 mm while riser

should be 150 mm.

c) Pressurisation: All internal staircases should be positively pressurised (forcible air

pressure) by using fans etc. to prevent the entry of smoke from other parts of the

buildings (air passes from the staircase into internal parts of the building) and no

service shaft should pass through it.

d) Ventilation: Any building having an area of more than 500 m2 per floor requires two

staircases and atleast one of them should be ventilated directly to the outside air on

an external wall because in an enclosed staircase, any smoke that escapes into it will

cause smoke logging and reduce light in exit as well as cause inhalations of fumes.

e) Segregation: The staircase leading from the higher floor to the ground floor and the

staircase coming from basement should be segregated so that fire from basement

should not reach to the ground floor. Eventually there should be two doors- one for

the basement evacuees and one for ground floor exit.

[3.3] Fire Escape Travel Distances

It is the maximum distance that a person needs to travel to reach the fire escape staircase

or ramp in case of a fire in any building: the distance is from the farthest corners of any

room through a door, passage or any other obstruction to the way of the fire escape

staircase. Some Escape Distances:

(i) Residential, Education and Institutional Buildings: 22.5 m

(ii) Business, Mercantile or Assembly Buildings: 30 m

(iii) Industrial Buildings: 45 m

If a building has sprinkler system of protection, the fire escape travel distances given

above are increased by 50 % for each category and if it is a basement, these distances are

usually halved.

[3.4] Refuge Areas

1. What is a refuge area?

The purpose of a refuge area is to allow people on higher floors to reach a position of

safety on the upper floors itself, if the vertical means of escape are blocked or ineffective.

The occupants of the refuge area are then evacuated by fire brigade staffs through special

recovery vehicles that can reach higher heights.

2. Design Considerations for Refuge Area:

a) It should be a secure place where fire should not reach and so its entry should be with

a 60 min fire rated door.

b) The periphery of the building facing the refuge area should have 230 mm brickwork

or non-combustible construction.

c) A Refuge area should be provided for a building with more than 24 m height i.e. a

building with more than 7-8 floors.

[3.5] Fire Escape Lifts (High Rise Buildings)

Fire Lift is a recue purpose lift with a fireman switch and fire resistant doors. It works like

any other normal lift but takes up power form DC i.e. a backup mode.

Requirements for Fire Lifts:

a) Max number of lifts in one lift bank = 4.

b) One fire lift should be provided 1200 m2 area of buildings.

c) Lift lobby should have self closing smoke stop door with 30 min fire rating.

d) In case the lift opens into the basement, lift well should be adequately pressurised.

[3.6] Requirements of Basements

The access to the basement shall be either from the main or alternate staircase providing

access and exit from higher floors.

Basements should not be used for kitchens, workshops, assembly spaces, storage if

inflammable oil or for installation of electrical Substation.

The basement shall be partitioned and in no case compartment shall be more than 500 sq

m. and less than 50 sq m. area except parking.

[3.7] Drive-way around buildings and Service shafts

1. Drive-way: the drive-way width should be atleast 4.5-6 m and there should be no parking

from the driveway towards to the building.

2. Service shafts: all service shafts shall be sealed at each floor levels to prevent the vertical

spreading of fire and smoke.

[3.8] AHU Shutoff

The air condoning system or air handling unit (AHU) should be switched off during a fire

because the return air allows air from any other area under fire to spread to another: since

an AHU feeds a no. of rooms, a fire in any room cases heat to be taken from the room and

then routed to AHU, from where it is again dispersed into all rooms causing the spread of

fire to all the other rooms.

Thus the AHU needs to be shut off. It is automatically switched off electrically by the fire

detection system. But if the AHU is serving only one space, say a Hall, then it does not

need to be tripped because there is no risk of spreading of fire to other rooms, except for

the AHU room itself. Some inferences:

(a) Air conditioned rooms should have windows and ventilators to vent out smoke.

(b) No duct should feed more than 2 floors: to prevent floor-to-floor fire spread.

(c) Automatic smoke venting should be provided in large halls.

[3.9]Fire Control Room

A Fire Control Room of 4 x 4 m should be provided on the ground floor of a high-rise or

multi-storey building as close to the entrance as possible for easy accessibility in case of

the mis-happening event of a fire.

The Control Rooms Houses the following:

(i) Fire Control Panel

(ii) Public Addressal System

(iii) Fire Extinguishers.

[3.10] Fire Hose Cabinet (FHC)

A cabinet housing a fire hose reel, pipes and high pressure water valves for emergency

use during a fire; to cool it down by hydrant is called a fire hose cabinet or FHC.

It measures 1200 mm X 600 mm in plan and it is a red coloured metal cabinet with a

glass front. In case of the emergency the glass front is broken; the hose reel is unrolled

and plugged to the water valves which splash water to cool down the fire.

It should be readily accessible during the fire with minimum distance from the fire prone

areas and can be recessed in wall or clear wall mounted.

CHAPTER 4: BUILDING SAFETY II: DESIGN AND PLANNING GUIDELINES

[4.1] Requirements for Building Design for Fire Safety

1. The level of combustible materials in a building to be reduced to the minimum.

2. There should be adequate fire escape staircases & fire lifts with min escape distances.

3. These Survival and Escape routes should be obstruction free.

4. All floors and vertical Shafts should be segregated all floors.

5. Special measures to be taken for basements: for smoke extraction &occupant evacuation.

6. All areas of the building should be adequately ventilated.

7. All Electrical Installations should be kept a little away from the building and should not

interfere with the fire protection systems,

8. Installation of active fire protection systems according to design guidelines.

[4.2] Design Guidelines for Fire Protection Systems (Detection and Suppression)

1. Purpose of the System (detect/suppress).

2. Protection goals of the owner.

3. Type of occupancy that needs to be protected.

4. Type, quality and quantity of the material present.

5. Required response time.

6. Area by area analysis of the building and its content in the form of results which one

wants to see.

7. Complete understanding/description of system operation including compatibility of all the

equipments that are interconnected.

[4.3] Fire Safety Guidelines for Housing Systems

1. Determine type of fire protection system required.

2. Allocate the space required for the equipments.

3. Integrate the entire fire services requirement.

4. Various ways of selecting systems:

(i) Fire safety is not mandatorily required in plotted housing as per law.

(ii) British law says any building having more than 20 occupants should have a smoke

detector.

5. Hose reels, hydrants, sprinklers etc are mandatory in all public buildings & basements.

6. Other requirements include: underground water storage tank with a diesel pump near it,

an electrical booster pump, fire control room and smoke controller.

7. Space requirement for a plant room (that consists of the above) is a must.

8. A fire escape plan is a must for every public building:

CHAPTER 5: FIRE SUPPRESSION AND SMOKE CONTROL

[5.1] Basic Suppression Methods of Fire

Suppression systems use a combination of dry chemicals and/or wet agents to suppress

equipment fires. Most common method is cutting on heat and the best way is to use water:

1. Hydrant and Hose Pipe System

2. Sprinkler System

3. Down Comer System

4. Wet Riser System

5. Dry Riser System

6. Gaseous Suppression

7. Manual Fire Extinguishers

[5.1.1] Hydrant System of Suppression

1. It is a water based system that has outlets for pressurised water at all floor levels. Pressure

is created through pressure pumps.

2. It is a manual system: in case of its use, the folded hose system has to be unrolled and

connected to hydrant and the nozzle at the end.

3. As soon as the hydrant flows the pressure causes the pump to start automatically and

water rushes out like a jet on the fire and cools it.

Planning Implication of Hydrants and Hose Stations

a) Generally a hose station must be provided per 1000 m2 area. Additional may be provided

if building length is more than 30 m.

b) Hose station size may be 1 m along corridor and depth should be 0.6 m

c) Hydrant Cabinet must be less than 36 m from any point of the floor.

d) Locate hydrants preferably near fire exit or fire escape passages, provided they do not

impede the way of escape.

e) Garden or external hydrants should be located less than 6 m from the building and not

more than 60 m from any point of the building.

f) Fire tender movement should be unobstructed around the building on 6 m hard paved

easily trafficable road.

[5.1.2] Sprinkler System

1. Consists of network of pipes (always charged with water) and heat sensitive sprinklers all

over the building. It is both-detection as well as suppression system: very reliable.

2. Sprinkler consists of a small glass bulb filed with a small amount of alcohol that expands

on a set temperature and on expansion, the bulb shatters and pen the nozzle that the bulb

holds in position.

3. The water discharges and forms an umbrella pattern of discharge with small droplets that

cover an area of 3.5-4 m in dia. This water cools the fire and extinguishes it.

4. Area that is protected varies with the height of room. The lower we put it, the lesser is the

area of coverage.

[5.1.3] Down Comer System

It is an arrangement of fire fighting within the building by means of s down-comer pipe

connected to a terrace tank through terrace pump, gate valve and non return valve and

having mains nor less than 100 mm internal diameter with landing valves ion each floor.

It is also fitted with inlet connections at ground level for charging with water by pumping

from fire service appliances and air release valve at roof level to release trapped air.

[5.1.4] Wet Riser System of Fire Suppression

1. A wet riser is a system of pipes (dia 3-4.5 inches) that are charged with pressurised

water, supplied by a mains pump and a storage tank fitted with a booster pump*.

2. Generally, wet risers are installed in large buildings more than 60 metres above ground

level and such systems can be identified from the outside, as there will be no visible pipe

system or water inlet for the fire brigade.

3. Inside the building, internal outlet valves can be found on staircase landings or at each lift

lobby and are clearly labelled; these outlets usually resemble taps.

4. In case of fire, the fire service will connect to the wet riser system: When the outlet valves

are opened, water immediately begins moving through the pipes and shoots out to help

extinguish the flames.

5. As the stored pressurised water leaves the wet riser, the pumps activate and begin to refill

the pipes with more pressurised water. This ensures a constant, steady supply of water

that allows the fire brigade to put out flames more efficiently.

*Location of Pump House: pump house of water tank should be located on ground floor level

only (as near to the system as possible) so that tank can be refilled easily & water is readily

available for fire fighting and not on roof because it adds to the dead load of the building, the

building height gets reduced, water overflow might affect the roof and the systems becomes

less effective. But if it is placed on the roof level, overflow of the tank needs to be checked

and transferred to another empty tank.

[5.1.5] Dry Riser System of Fire Suppression

1. A dry riser is a main vertical pipe intended to distribute water to multiple levels of a

building less than 15 m of height as a component of the fire suppression systems.

2. The pipe is maintained empty of water: The dry riser is the opposite of a "wet riser"

system where the pipes are kept full of water.

3. Dry pipe fire sprinkler system is a network of pipes connected to fixed sprinklers inside a

building, which are full of air until one of the sprinklers is triggered.

Planning Considerations

a) Dry risers have to have fire engine access within 18 m of the dry riser inlet box.

b) Dry risers in occupied buildings have to be within a fire resistant shaft, usually one of a

building's fire escape staircase enclosures.

[5.1.6] Gaseous Fire Suppression - Gas: FM 20

Principle of working: reducing oxygen content or breaking down the chemical cycle of

fire in an enclosed environment.

This system consists of high pressure cylinders with electric actuator that release inert gas

or chemical agents to extinguish fire and are connected with highly pressurised pipes. It is

an automatic system.

A typical system consists of the agent, agent storage containers, agent release valves, fire

detection system and agent delivery piping.

Various agents used are:

(i) Carbon dioxide: reduces oxygen amount substantially.

(ii) FM-200: colourless, liquefied compressed gas stored as a liquid and dispensed

into the hazard as a colourless, eclectically non-conductive vapour that is clear

and does not obscure vision.

(iii) Inergen and Halon: Highly pressurised systems.

[5.1.7] Fire Extinguishers (Cutting Oxygen Supply)

A. Types of Fire Extinguishers:

a) Type A: Extinguishes fire from wood, paper etc.

b) Type B: Extinguishes fire from liquids and solvents.

c) Type C: Extinguishes electrical fires.

d) Type ABC: Extinguishes all of the above combined and for metals.

B. Types of Extinguishing Agents:

(i) Water: Used for type A but not suitable for B and C.

(ii) Foam: Used for type A and B but not for C.

(iii) Dry Powder: Used for all A, B and C. Best for B.

(iv) Carbon Dioxide: Used for type C mainly, can be used for B also.

[5.2] Control of Smoke

1. Objectives of Smoke Control Systems:

a) To keep escape roots free from smoke.

b) To reduce toxic gases and fumes.

c) To delay full development of fire.

d) To reduce thermal damage of building during fire.

2. Methods of Controlling Smoke:

a) Open able or removal doors and windows.

b) Pressurised vents on the roof.

c) Roof mounted fans and exhaust systems.

d) Forced air conditioning or mechanical ventilator systems.

[5.3] Concept of Intelligent Building

A building is an intelligent building if it has:

1. Good Security System and CCTV Cameras.

2. Access Control System Proximity Type (Eg. Remote control) or Biometric type

(fingerprints or retina scan).

3. Intruder Detection Laser Beam and IR Coding

___________________________________________________________________________

ASSIGNMENT ON FIRE SAFETY

1. State the design guidelines for fire detection system and explain any two in detail.

2. Explain the Wet riser and Dry riser systems of fire fighting with neat sketches. Discuss

the location of the pump house used in both cases.

3. What are the fire safety standards and fire safety design guidelines that must be followed

for various multi-storey buildings being constructed?

4. What are the objectives of Smoke Control in a building? How can this be done?

5. State the NBC rules for the construction and design of fire escape staircases in buildings.

6. Write Short notes on the following (draw supporting sketches):

(i) Fire Escape Distances

(ii) Types of Manual Fire Extinguishers

(iii) Types of Smoke Detectors

(iv) The Stages of Fire

(v) Fire Hose Cabinets (FHC)