1) Electrical safety involves understanding atoms, electrons, and how electricity is generated through magnetism. Proper safety practices are needed to prevent electrical shock and burns. 2) Circuit breakers automatically open electrical circuits under abnormal or normal conditions to prevent overloading. They carry full load currents and can manually or automatically make or break operating currents. 3) Arc flash occurs when electricity arcs from one conductor to another or ground, producing intense heat and pressure that can severely burn or injure a person. Proper personal protective equipment and safety procedures are required when working on energized equipment.

1. Electrical Safety
By
Mr. Kalyanam Sudheer Kumar
Safety Engineer

2. ELEMENTS & ATOMS
Every known substance – solid, liquid or gas is composed of elements
An atom is the smallest particle of an element that retains all the properties of that element
Each element has it’s own kind of atom

3. ATOMS
Each element has a definite number of electrons ----and the same number of protons
They are oppositely charged and therefore attract each other. This tends to hold the electrons in
orbit around the atom.

4. ELECTRICALLY BALANCED ATOM

5. What is voltage/Electro Motive Force?
The force required to move a pair of charges to a unit distance overcoming their intermolecular forces
Is called voltage. Units: volts. Symbol: V
What is current?
Charges move randomly in the absence of EMF. When EMF is applied across a conductor they tend to
move in a unique direction from one end of the conductor to the other end constituting electrical
current. Units: Amperes. Symbol: I
What is resistance?
It is the physical property of a substance in which charges collide with each other when an EMF is
applied by which energy is lost in the form of heat. Units: ohm. Symbol:
What is Electric Shock?
It is defined as a sudden violent response to electric current flow through any part of the body.

6. ELECTRICAL MATERIALS
Resistance: When an EMF is applied across a material charge collide with each other and energy
is lost in the form of heat. It is the physical property of that material.
CONDUCTOR – contains many free electrons --- gold, copper, silver, aluminum
INSULATOR – contains few free electrons-Usually non-metallic such as wood, rubber, glass, etc

8. GENERATING ELECTRICITY
Friction, pressure, heat, light, chemical reaction, and magnetism
Magnetism is most practical & inexpensive method
Electricity is produced when a magnet is moved past a piece of wire, or wire is
moved through a magnetic field

9. OHM’S LAW
George Simon Ohm
◦ Formulated a mathematical relationship between:
◦ Current
◦ Voltage
◦ Resistance
◦ Resistance = Impedance
◦ Resistance = DC
◦ Impedance = AC
◦ Interchangeable – Most Branch circuits

10. v
5v
0v
-5v
5v
0v
-5v
t
t
AC
DC

11. DIRECT CURRENT
Always flows in one direction
Used to charge batteries, run some motors, operate magnetic lifting devices and welding
equipment.

12. ALTERNATING CURRRENT
More common in electrical work
Changes rapidly in both direction and value
Power companies produce power cheaper with alternating current

14. Circuit Breaker:
It is a device designed to close/make or open/break the electrical circuit under
abnormal and normal conditions automatically and also manually.
Duties of a circuit breaker are:
 It carries the full load current continuously without overheating and damage.
 It opens and closes the circuit on load. Acts as a switch.
 It makes and breaks the normal operating current of magnitude up to which it
is designed for (automatically).
 It makes and breaks the circuit the normal operating current (manually for
switching purpose).
Moving
Contact
Fixed
Contact
Moving
Contact
Fixed
Contact

15. How does a circuit breaker operate automatically?

16. Fixed
Contact
Moving
Contact
Arc
Insulating Fluids commonly used for circuit breakers are:
Air at atmospheric pressure
Compressed Air
Oil producing Hydrogen for Arc Extinction
Ultra high Vacuum
Sulphur Hexa Floride

20. 1)Phase to Earth Fault
2)Phase to Neutral Fault
3)Phase to Phase Fault
4)Earth Leakage Fault
5)DC Positive to Negative Fault
6)DC Positive/Negative to Earth Fault
7)Interturn Fault

21. Electrical Hazards
Electrical Burns
Electrical Shock
Electrical Arc
Electrical Fires and
Electrical Explosion
Secondary Hazard

22. Human body consists 70% of water which makes the body a good conductor of Electricity.
The severity of the electrical shock depends up on:
1) Current Rating.
2) Voltage Rating.
3) Precipitation of human body.
4) Duration of contact.
5) Nature of contact.
6) Current path through the body.
7) Conductivity/ Resistance of the body.
8) Conductivity of the Environment.
9) Age/ Health Status of the victim.

23. Electric Shock
Received when current passes
through the body
Severity of the shock depends on:
◦ Path of current through the body
◦ Amount of current flowing through
the body
◦ Length of time the body is in the
circuit
LOW VOLTAGE DOES NOT MEAN LOW
HAZARD
Exit
Ground
Entrance

25. Possible Effects of Electricity on :
 Cardio Respiratory Effects: The risk of fatal injury due to
disruption to heart rhythm.
 Muscular Contraction: Resulting in an involuntary grip
on the live conductor, thus prolonging current flow through
the body.
 Tissue Burns: Main sites of damage being at the entry
and exit points with the possibility of damage to internal
organs.
 Fractures or Dislocations caused by fall.

26. Arc Flash & Arc Blast
Arc Flash – electrical short circuit that
occurs when air flashes from an exposed
live conductor, to either another
conductor or to ground.
Arc Blast – pressure wave caused by the
arc flash.

27. Arc Flash/Blast
Concentrated energy explodes outward
High intensity flash
Temperatures can reach 35,000
Pressure wave can reach 200lbs/sq. inch
Vaporize conductors and copper and
explode particles like buckshot.

28. Causes of Arc Flash (cont.)
Buildup of dust, corrosion on insulating
surfaces
Improper maintenance
Sparks produced during racking of
breakers, replacement of fuses and closing
into faulty lines.
Inattentiveness/Overconfidence

29. Causes of Arc Flash
Improper training
Improper work procedures
Dropped tools
Accidental contact with electrical
systems
Installation failure
Inadequate SCCR
Voltage testing with inappropriate
equipment`

30. Arc Flash Effects
Severe burns
Broken bones
Vision damage
Hearing loss
Brain/internal injuries
Punctures and lacerations
Death

32. Run over by vehicles.
Being dragged over rough surfaces.
Becoming trapped in machinery.
Coming in contact with hot, corrosives or chemicals/ solvents.
Continuous flexing.
Connection leads pulled out of cord rips.
The making of wrong connections in the plug or other fittings.
Poor Earth connections.
No over load protection being provided.
Unsafe work practices.

33. Equipment is tested on periodic and routine basis.
All cables are to be provided double insulation.
Equipment, plugs, connectors and cables are free from damage.
Correct wiring and sound connections.
Fuses and other means preventing excess current with correct rating in place.
System not overloaded.
Visual inspection for damage to cables, plugs and sockets.
Provided with means of isolation after use.
Never leave the electrical equipment when the supply is on.

34. Poor Design of Electrical Equipment.
Defective Wiring such as damaged cables/ loose connections.
System faults such as short circuits.
Ignition of flammable or combustible materials due to arcing,
sparking from switches or motors and Static electricity.
Incorrect fuse rating.
Overloaded Electrical sockets with multiple adapters.
Unauthorised wiring and fuse replacement.
Poor Ventilation on equipment leading to overheating.
Lack of adequate maintenance.
Coiling of Cables.

35. Emergency Actions for Electrical Shock:
Isolation of victim from the supply.
Summoning Help.
Administrating first aid such as Cardio Pulmonary Respiration.
Treatment of burns and other injuries.
Taking the victim to the nearest hospital.

36. Ways to prevent :
Isolation (LOTO)
Double Insulation
Earthing
Equipment Earthing
Neutral Earthing
Protective Devices
In accessible to live equipment
Use of Low Voltage

37. LOTO-Lock out Tag Out System

38. Safe Work Practices
◦ De-energize-Lockout Policy
◦ Don’t wear conductive apparel
◦ Work area must be illuminated
◦ Never reach into blind spots
◦ Don’t allow conductive liquids near electrical work or equipment
◦ Buddy system (over 1,000 volts, work in pairs)
◦ Do not defeat electrical interlocks
◦ Use nonconductive ladders

39. Qualified Persons Training Requirements
One who has the skill and knowledge related to the construction and operation of the
electrical equipment and installations and has received safety training to recognize and avoid
the hazards involved.
May be considered qualified with respect to certain equipment & method but still
unqualified for others.
Understand specific electrical hazards
Knowledgeable of the construction and operation of the equipment
Identify & understand the relationship between electrical hazards and possibly injury
Distinguish exposed live parts
Able to determine voltage of live parts
Understands and complies with arc flash and shock hazard boundaries.

40. Safeguard for Personnel Protection
Personal Protective Equipment:
◦ Must use when exposed
◦ Maintenance
◦ Inspection
Insulated hand tools
Guarding of exposed parts during work

41. Qualified Persons Training (cont.)
◦ Proper use of precautionary techniques
◦ PPE, including arc-flash & shock protection
◦ Insulated tools
◦ Demonstrate how to select and use a voltage
meter
◦ Decision-making process used to determine the
degree and extent of the hazard

42. Arc Ratings
*NFPA 70E Table 130.7(C)(11)
Hazard/Risk
Category
Incident Energy
(cal/cm2)
0 0 - 1.2
1 1.2 - 4
2 4 - 8
3 8 - 25
4 25 - 40
Dangerous Over 40

43. Arc Flash Label

44. Arc Flash Label

45. NFPA 70E Approach Boundaries (cont.)
The qualified
worker is
responsible for
ensuring physical
barriers are in
place and all
approach
boundaries are
enforced during
work.
! WARNING
Arc Flash and Shock Hazard
Appropriate PPE Required
34 inch Flash Hazard Boundary
3.46 cal/cm^2 Flash Hazard at 18 inches
Class 1
VR Gloves-Tools, Proper Clothes, Safety Glasses,
Hardhat
480 VAC Shock Hazard when cover is removed
42 inch Limited Approach
12 inch Restricted Approach
1 inch Prohibited Approach
Bus Name: PP-MCC-G81, Prot Device: PP-PDP-G71-6
ProhibitedRestrictedLimited
Flash Boundary – 4 ft. or calculated
Warning label
provides
boundary
information

46. Specific Tasks
Troubleshooting only! NO “WORK!”
◦ Checking / replacing fuses
◦ Checking motor starters
◦ Checking amp drawn
◦ Checking relays

47. Voltage-rated Gloves
First line of defense
Choose the right size
Leather protectors must be worn over the rubber gloves
Gloves must be tested
◦ Before first issue and every 6 months
◦ If tested, but not issued for service, glove may not be put into service unless tested within
previous 12 months.
Checked before use
◦ Roll-up test
◦ Inflator test
 Salisbury
video

48. PPE - Hazard Risk Category 4
25 - 40 cal/cm2
40+ flashsuit w/ hood over FR long
sleeve shirt and long pants
Safety glasses
Arc rated faceshield
Hearing protection (inserts)
VR gloves
Leather gloves
Leather work boots