This document discusses electrical safety. It begins by providing analogies to explain concepts like current, voltage, and resistance using water flow. It then discusses hazards of electricity like shock, fires, explosions, and arc flash. Examples of injuries from electrical burns and contact are shown. The importance of earthing and residual current devices in prevention electrocution is explained. Personal protective equipment requirements and safety boundaries are outlined. Lock out tag out procedures and their importance for maintenance safety is also covered. Throughout examples and diagrams are provided to illustrate electrical safety concepts and hazards.

1. Electrical Safety
Berger Paints India Limited
1st Oct’22
Prepared by – Sumanta Gupta

2. Fundamentals of Electricity
Electrical Safety
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Resistance = Diameter of Hose
Example – Larger hose (less resistance), more
water flows
Voltage = Water Pressure
Example – 2 kg/cm2
Current = Flow Rate
Example – 20 Ltr per min
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3. Electrical Safety
• Electrical current is the flow of electrons through
a conductor.
• Voltage a measure of electrical force.
• Resistance opposes electron flow.
• A conductor is a material that allows electrons to
flow through it.
• An insulator resists the flow of electrons.
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Fundamentals of Electricity
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4. Electrical Safety
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Hazards of Electricity
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5. Electrical Safety
• Shock – Most common and can cause electrocution or
muscle contraction leading to secondary injury which
includes falls and burns
• Fires – Enough heat or sparks can ignite combustible
materials
• Explosions – Electrical spark can ignite vapors in the air
• Arc Flash - Can cause burns ranging from 14,000° F to
35,000° F.
• Arc Blast – In a short circuit event copper can expand
67,000 times. The expansion causes a pressure wave.
Air also expands adding to the pressure wave.
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Hazards of Electricity
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6. Electrical Safety
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Arm with third degree burn from High
Voltage Line
The knee on the left was energized
and the knee on the right was
grounded
Contact electrical burns
Hazards of Electricity
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7. Electrical Safety
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Hazards of Electricity
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8. Electrical Safety
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Electrical Contact Hazard
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9. Electrical Safety
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Touch & Step Potential
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10. Electrical Safety
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Electrical Shock
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11. Current stops
Safe to touch
Fuse Blows
Transformer
Equipment
Earthed
6 A Fuse / MCB
Current - Hundreds
of Amp
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Necessity of Earthing
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12. Electrical Safety
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Earthing
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13. Transformer
Equipment
Earthed
Fuse Does not Blow
Current is 240
miliampere
Human Body
Resistance 1000 ohm
240
V
6 A Fuse / MCB
Result - Electrocution
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Earthing
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14. Principle of operation of a Residual Current Device.
Circuit is Safe now
Sensitivity – 30 ma
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Residual Current Protection
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15. Principle of operation of a Residual Current Device.
Circuit Disconnected - Person is safe
Sensitivity – 30 ma
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Residual Current Protection
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16. Electrical Safety
• Type 1 Coordination
Under short circuit conditions, the contactor or starter shall
cause no danger to persons or installation and may not be
suitable for further service without repair and replacement of
parts.
• Type 2 Coordination
Under short circuit conditions, the contactor or starter shall
cause no danger to persons or installation and shall be suitable
for further use. The risk of contact (light) welding is recognized, in
which case the manufacturer shall indicate the measures to be
taken in regards to equipment maintenance.
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Short Circuit Protection for Motor Starter
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17. Electrical Safety
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Short Circuit Protection
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18. Electrical Safety
• An arc flash occurs when electrical current
passes through air
• This most often occurs in power systems when:
- Making or breaking a circuit
- Bridging a insulating air gap with a more
conductive object
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Arc Flash
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19. Electrical Safety
800-1000° C 1800° C 7000° C
Arc Flash
Up to
35,000° F
Or
20,000° C
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Arc Flash
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20. Electrical Safety
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Arc Flash
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21. Electrical Safety
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Arc Flash
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22. Electrical Safety
Flash Protection Boundary
An unqualified person may only cross this
boundary accompanied by a qualified worker.
Should an arc flash occur, the person exposed
to the blast would be subjected to the heat
generated by the flash resulting in second
degree burns (1.2 calories/cm2) which is
typically curable. At this distance PPE must be
worn to prevent 2nd degree (or greater) burns
if exposed to the arc flash.
Limited Approach Boundary
Only qualified persons within this boundary.
This is the distance an unqualified person may
enter when continuously accompanied by a
qualified worker, wear the appropriate level of
PPE and trained for the task.
Restricted Approach Boundary
Shock Protection and Flash Protection. This
boundary is restricted to unqualified
personnel. Only a qualified worker, wearing the
appropriate level of PPE and properly trained
for the task to be performed may enter this
area. It also requires an approved work permit
with a written plan of the task to be performed.
Ref. NFPA 70E 2015
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Flash Protection Boundary
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23. Electrical Safety
Ref. NFPA 70E 2018
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Approach Boundary for Alternating Current
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24. Electrical Safety
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PPE – Personal Protective Equipment
Ref. NFPA 70E 2018
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25. Electrical Safety
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PPE – Personal Protective Equipment
Ref. NFPA 70E 2018
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26. Electrical Safety
• Energies - electrical, mechanical, hydraulic,
pneumatic, chemical, thermal, gravity and others.
• Prevents release of hazardous energy.
• Power sources “isolated and inoperative”.
• Includes stored or residual energy.
• De-energizes machines & equipment.
• Uses energy isolating devices.
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LOTO – Lock Out / Tag Out
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27. Electrical Safety
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Lock Out – Isolation of energy from the system (a
machine, equipment, or process) which physically
locks the system in a safe mode.
LOTO – Lock Out / Tag Out
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28. Electrical Safety
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Tag Out – Labelling process to indicate why LOTO is
required & equipment being controlled cannot be
operated until tag is removed.
LOTO – Lock Out / Tag Out
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29. Electrical Safety
Protects Employees & You
• From injury
• From unexpected start-up.
• During service & maintenance work.
• Working near exposed electrical conductors &
parts of electrical equipment.
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LOTO – Lock Out / Tag Out
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30. Electrical Safety
Requirements
• ONLY authorized employees perform LOTO.
• ALL Employees must be trained.
• Use proper locks and tags.
• Written LOTO procedures.
• Review procedures annually.
• Follow LOTO each time – every time.
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LOTO – Lock Out / Tag Out
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31. Electrical Safety
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LOTO – Lock Out / Tag Out
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32. Electrical Safety
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MCB Lock Out Procedures
LOTO – Lock Out / Tag Out
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33. Electrical Safety
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• Provide Interlocks with Enclosures
• Provide Shrouds, Insulation, Barricading etc.
• Proper Earthing System with Effective Earthing
• Protection against Leakage Currents
• Use of Safe Low Voltage – wherever possible
• Strict Adherence to “Permit To Work” system
• No maintenance activities on “Live” Electrical System
• Use of PPE
• Perform “LOTO” during Maintenance
• Ensure Safety Design & Integrity of Electrical Equipment
(including Flameproof Fixtures)
• Visual Inspection / Thermography / Preventive
Maintenance
Protection against Electrical Hazards
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34. Electrical Safety
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