MUDIT MAHESHWARI

MAKING ELECTRICAL AND FIRE SAFETY MANAGEMENT

EFFECTIVE

ITC LIMITED

ELECTRICAL SAFETY

Electrical Mishaps & Accidents

Need for safe work environment

ALL INDIA ACCIDENT STATISTICS

Source: https://data.gov.in/

• Design, procurement

and installation as per

standards

• Training & Behavioural

controls

• Robust tracking through

Audits/ Inspections

• Operation & Maintenance

as per standards

SAFETY MANAGEMENT IN ITC LIMITED

SAFETY HAZARDS✓ITC’s Approach

✓Electrical & fire safety starts at the drawing board.

✓Designs of all projects is done as per national and international codes & standards, e.g., BIS, IEC, NFPA, IEEE etc.

✓Power system designs undergo a check at Corporate level - verification vis-à-vis codes, standards, best practices, etc.

✓Existing systems maintained as per BIS and international codes & standards and undergo periodic audit/ verification from Corporate

ELECTRICAL SAFETY

✓ Main hazards - Electrocution & Fire

✓ More importantly – Mitigation and prevention at different stages

✓ Then what should be the approach?

✓Design as per codes & standards

✓Procurement as per codes & standards

✓Installation as per codes & standards

✓Operation & Maintenance as per codes & standards

This is the process followed in ITC

STAGE WISE PREVENTION & MITIGATION

✓Design - example of Earthing & Lightning

✓Procurement – example of Transformer

✓Installation – example of Cable

✓O & M – example of Switchgear panels

Electrical Safety

✓IEC 61140 & IS 3043 provides guidance for protection against electric shock.

✓Under normal conditions – hazardous live parts shall not be accessible.

✓Under fault conditions – accessible conductive parts shall not be hazardous.

Measures adopted to protect against this hazard, include;

✓Automatic disconnection of power supply.

• Let us start with the minimum basic safety requirement for automatic disconnection of power supply system.

• Interventions in earthing system design

DESIGN STAGE - EXAMPLE

EART

HIN

G

As per IS:3043 - 1987 Clause 12.2.2.1

Issc/S = k/√t

S = (Issc *√t)/k

where

S = Cross-sectional Area (sq.mm)

Issc = Value (ac, rms) of fault current (Amp)

t = Operating time of disconnection device (sec)

k =

Available Parameters

t = 1 sec (max)

k = 80 (for Steel with initial temp 40 deg C & final temp 500 deg C)

= 205 (for Copper with initial temp 40 deg C & final temp 395 deg C)

Earthing Strip Area Calculations (GI)

Issc (Amp) t (sec) k (for bare

Steel)

Earthing Strip Area

(sq. mm)

Corrosion Allowance Final Earthing Strip

Area Requirement

(sq.mm)

GI Earthing Strip

Size (sq. mm)

10,000 1 80 125 15% 144 25 x 6

18,000 1 80 225 15% 259 50 x 6

25,000 1 80 313 15% 359 50 x 10

35,000 1 80 438 15% 503 50 x 10

42,000 1 80 525 15% 604 75 x 10

50,000 1 80 625 15% 719 75 x 10

65,000 1 80 813 15% 934 2 x 50 x 10

Earthing Strip Area Calculations (Cu)

Issc (Amp) t (sec) k (for bare

Copper)

Earthing Strip Area

(sq. mm)

Corrosion Allowance Final Earthing Strip

Area Requirement

(sq.mm)

Cu Earthing Strip

Size (sq. mm)

10,000 1 205 49 15% 56 25 x 3

18,000 1 205 88 15% 101 25 x 6

25,000 1 205 122 15% 140 25 x 6

35,000 1 205 171 15% 196 40 x 6

42,000 1 205 205 15% 236 40 x 6

50,000 1 205 244 15% 280 50 x 6

65,000 1 205 317 15% 365 50 x 10

Factor dependent on the material of the protective conductor, the insulation & initial & final

Temepratures

Earthing Strip Sizing Basis

DESIGN STAGE - EARTHING

200 amps circuit breaker

Earth resistance 0.8 Ω Earth resistance 0.8 Ω

Bonding wire 300m, 70sq mm

copper @0.2 Ω /km = 0.06 Ω

Without bonding fault current = 240 / 1.6 = 150 amps (circuit breaker will not trip)

With bonding fault current = 240 / 0.06 = 4000 amps (circuit breaker trips instantly)

DESIGN STAGE – LIGHTNING PROTECTION

Precautions against lightning

LIGHTNING PROTECTION

Source: https://NCRB.gov.in

LIGHTNING PROTECTION✓ Air termination location – Angle method or Rolling sphere method

✓ An equal spacing of downconductor is preferred around the perimeter of the

building/ structure. Typical preferred values of distance between the

downconductors should be as per following table.

LIGHTNING PROTECTION

LIGHTNING PROTECTION

CHECKING DURING PROCUREMENT

Equipment – transformer / motor / switchgear / cable / UPS etc., conforms to relevant standards.

How to verify ?

Check the type test report and verify it as per relevant standard.

Check the routine test report and verify it as per relevant standard.

Let us see the same for a power transformer ..

CHECKING DURING PROCUREMENT

Tests on a power transformer (Refer IS 2026 & IEC 60076)

Type tests Temperature rise test as per IS 2026-2

Lightning Impulse test as per IS 2026-3

Routine tests Winding resistance

Voltage ratio and phase displacement

Short circuit impedance and load loss

No-load loss and current

Dielectric routine tests

Tests on OLTCs.

✓Most common failures for oil filled transformers

✓OLTCs

✓Bushing failure

CHECKING DURING INSTALLATION

CHECKING DURING INSTALLATION

✓Mode of power cable laying

✓MV power cables directly buried

IS 1255 : Installation & maintenance of

power cable

CHECKING DURING O & M✓Relevant codes of practice to be followed. For LV switchgear assemblies:

➢Annual mV drop test across terminations or thermography tests.

Refer IS 16168

CHECKING DURING O & M

FIRE SAFETY

STEPHEN COURT - KOLKATA

Date of tragedy: 23rd March 2010

Fatalities: 43

COACHING CENTRE – SURATCourtesy Inshorts

TROUBLING ISSUES

Preliminary investigations (for various incidents) revealed:

1. Deviations from the approved municipal plan

2. Highly flammable materials stored

3. Exit routes and emergency exit staircases locked

25

WE, MUST KNOW

What are the fire risks/ hazards involved in the process/ operations?

Are the risks acceptable ?

Who could be harmed ?

Can the risks be reduced by altering designs or use of alternate technology/ materials ?

What are the statutory Implications?

Which codes/ standards are applicable ?

What types of fire safety systems are required?

FACTORS INFLUENCING FIRE SAFETY

Factories Act and State factory Rules

National Building Code of India

Oil Industry Safety Directive (OISD)

Petroleum Act and Rules

CEA Regulations 2010 (Measures relating toSafety and Electric Supply)

Insurance

Risk Assessments

FIRE PROTECTION

How to restrict fire?

Incipient

stage

Smouldering

stage

Flaming

stage

Fully developed

stage

Degradation

stage

Time

Tem

p

FIRE PROTECTION

How to restrict fire?

Prevent Ignition:

• Good House Keeping

• Good Storage Practices

• Good Engineering practices

• Good O&M practices

Incipient

stage

Smouldering

stage

Flaming

stage

Fully developed

stage

Degradation

stage

Time

Tem

p

• Adopt standards

• Best training

management

FIRE PROTECTION

How to restrict fire?

Control combustion:

Use of Fire retardant/ non-combustible

material for interiors, Upholstery, office

partitions, false ceiling etc.

Incipient

stage

Smouldering

stage

Flaming

stage

Fully developed

stage

Degradation

stage

Time

Tem

p

FIRE PROTECTION

How to restrict fire?

Suppress fire:

• Portable fire extinguishers

• Automatic sprinklers

• Water mist suppression systems

• Special extinguishing systems

Incipient

stage

Smouldering

stage

Flaming

stage

Fully developed

stage

Degradation

stage

Time

Tem

p

FIRE PROTECTION

How to restrict fire?

Restrict by construction:

• Fire compartmentation

Incipient

stage

Smouldering

stage

Flaming

stage

Fully developed

stage

Degradation

stage

Time

Tem

p

Almost 74% of fire deaths have been due to panic and inhalation of smokeand other toxic fire gases. (Source: NFPA)

Causes of deaths

Inadequate exiting arrangements

Exits kept locked preventing people from escaping

Inhalation of toxic gases such as Carbon monoxide, hydrogen cyanide (burning of plastics),phosgene (vinyl materials), etc.

FIRE PROTECTION

• Typical Building 3-D view

BASEMENTS 1,2

KC

ITC 1

IT1 [ building with fire consideration]

FIRE PROTECTION – EGRESS MODELLING

FIRE PROTECTION

FIRE PROTECTION

Emergency Egress and Relocation Drills Shall be held with sufficient frequency to familiarize occupants with the drill

procedure and to establish conduct of the drill as a matter of routine.

Planning and conduct of drills shall be assigned only to competent persons.

To be held at expected and unexpected times and under varying conditions.

Orderly evacuation should receive priority over the speed of evacuation.

Occupants should be accounted for.

A record shall be kept.

Sources: Oregon Fire Code, NFPA, OSHA.

FIRE PROTECTION - TRAINING

FIRE PROTECTION

✓Standards followed in ITC

✓BIS

✓IEC

✓IEEE

✓BS EN

✓NFPA

ADOPTING STANDARDS & CODES TO ENSURE EFFECTIVE SAFETY MANAGEMENT SYSTEMS

Overview through Design Reviews and Audits

✓ Best in class Hazard Identification and Risk Assessment System

✓ Work permit controls

✓ Training Management

✓ Accident Investigations

✓ Usage of PPEs enforced

BEST PROCESSES TO ENSURE EFFECTIVE SAFETY MANAGEMENT SYSTEMS

Overview through Audits and Inspections

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