safety

1. 1
First Aid on Electrical Shock

2. 2
Electrical Terms
• Current -- electrical movement (measured in amps)
• Circuit -- complete path of the current.
Includes electricity source, a conductor, and the output
device or load (such as a lamp, tool, or heater)
• Resistance -- restriction to electrical flow
• Conductors – substances, like metals, with little
resistance to electricity that allow electricity to flow
• Grounding – a conductive connection to the earth
which acts as a protective measure
• Insulators -- substances with high resistance to
electricity like glass, porcelain, plastic, and dry wood
that prevent electricity from getting to unwanted areas

3. ELECTRICAL SAFETY
State safety laws have helped to provide
safe working areas for electricians.
Individuals can work safely on electrical
equipment with today's safeguards and
recommended work practices.
• Report any unsafe conditions, equipment, or
work practices as soon as possible
3

4. 4
Electricity - The Dangers
• Electric shock occurs when an electric current
flows through the body. The human body is
made up of 60% to 70% water. This makes it a
good conductor of electricity. Burns, damage to
internal organs, heart rhythm problems,
Respiratory depression and death can result
from electric shock.

5. Electrical shock
Electrical shock occurs when a person
comes in contact with two conductors of a
circuit or when the body becomes part of the
electrical circuit. In either case, a severe
shock can cause the heart and lungs to stop
functioning. Also, severe burns may occur
where current enters and exits the body.
5

6. Electrical Shock
An electrical shock is received when electrical
current passes through the body.
You will get an electrical shock if a part of your
body completes an electrical circuit by…
• Touching a live wire and an electrical ground, or
• Touching a live wire and another wire at a
different voltage.

7. Safe Current Values
• 1 mA or less
Causes no sensation - not felt
1 mA to 8 mACauses
Sensation of shock, not painful;
Individual can let go at will since
muscular control is not lost.
7

8. Unsafe current values
8 mA to 15 mA
Painful shock; individual can let go at will
since muscular control is not lost.
15 mA to 20 mA
Painful shock; control of adjacent muscles
lost; victim can not let go.
50 mA to 100 mA
Ventricular fibrillation - a heart condition
that can result in death - is possible.
Difficulty in breathing
8

9. Unsafe current values
• 100 mA to 200 mA
Ventricular fibrillation occurs.
200 mA and over
Servere burns,
severe muscular contractions
so severe that chest muscles
clamp the heart shock
9

10. • Currents between 100 and 200 milliamperes
(0.1 ampere and 0.2 ampere) are fatal.
• Anything in the neighborhood of 10
milliamperes (0.01) is capable of producing
painful to severe shock
10

11. ELECTRICAL SAFETY
 Any current over 8 mA is considered potentially
dangerous
 It's not the voltage but the current that kills
 People have been killed by 100 volts AC in the
home and with as little as 42 volts DC. The real
measure of a shock's intensity lies in the amount of
current (in milliamperes) forced through the body.
Any electrical device used on a house wiring circuit
can, under certain conditions, transmit a fatal
amount of current. 11

12. 12
1. Natural (Touching of high-voltage source)
2. Man made
Source of Electrical shock

13. 13
Electrical Injuries
There are four main types of electrical injuries:
• Direct:
Electrocution or death due to electrical
shock
Electrical shock
Burns
• Indirect - Falls

14. 14
Shock Severity
• Severity of the shock depends on:
Path of current through the
body
Amount of current flowing
through the body (amps)
Duration of the shocking
current through the body,
• LOW VOLTAGE DOES NOT
MEAN LOW HAZARD

15. 15
Dangers of Electrical Shock
• Currents above 10 mA* can
paralyze or “freeze” muscles.
• Currents more than 75 mA can
cause a rapid, ineffective
heartbeat -- death will occur in a
few minutes unless a defibrillator
is used
• 75 mA is not much current – a
small power drill uses 30 times as
much
* mA = milliampere = 1/1,000 of an ampere
Defibrillator in use

16. 16
Burns
• Most common shock-related
injury
• Occurs when you touch
electrical wiring or equipment
that is improperly used or
maintained
• Typically occurs on hands
• Very serious injury that
needs immediate attention

17. 17
Falls
• Electric shock can also
cause indirect injuries
• Workers in elevated
locations who experience
a shock may fall,
resulting in serious injury
or death

18. MAN OF SAFETY
18

19. Before removing any fuse from a circuit, be sure the
switch for the circuit is open or disconnected. When
removing fuses, use an approved fuse puller and
break contact on the hot side of the circuit first.
When replacing fuses, install the fuse first into the
load side of the fuse clip, then into the line side.
A groundfault circuit interrupter (GFCI) is an
electrical device which protects personnel by
detecting potentially hazardous ground faults and
quickly disconnecting power from the circuit.
19

20. ELECTRICAL SAFETY
• Make sure there is a third wire on the plug for
grounding in case of shorts. The fault current
should flow through the third wire to ground
instead of through the operator's body to
ground if electric power tools are grounded
and if an insulation breakdown occurs.
20

21. Lockout
• Lockout is the
process of removing
the source of
electrical power and
installing a lock
which prevents the
power from being
turned ON
21

22. Tag out
Tag out is the process
of placing a danger
tag on the source of
electrical power
which indicates that
the equipment may
not be operated until
the danger tag is
removed.
22

23. 23

24. OSHA Office of Training & Education 24

25. 25
Servicing electrical equipment that does not require power to be ON to
perform the service
Removing or bypassing a machine guard or other safety device
The possibility exists of being injured or caught in moving machinery
Clearing jammed equipment
The danger exists of being injured if equipment power is turned ON
A lockout/tagout is used when:

26. 26
A danger tag has the same importance and
purpose as a lock and is used alone only when
a lock does not fit the disconnect device. The
danger tag shall be attached at the disconnect
device with a tag tie or equivalent and shall
have space for the worker's name, craft, and
other required information. A danger tag must
withstand the elements and expected
atmosphere for as long as the tag remains in
place.

27. Electrical Safety
• Electrical power must be removed when
electrical equipment is inspected, serviced, or
repaired.
• To ensure the safety of personnel working
with the equipment, power is removed and
the equipment must be locked out and tagged
out.
27

28. 28
Electrical Hazards and How to
Control Them
Electrical accidents are
caused by a combination
of three factors:
Unsafe equipment
and/or installation,
Workplaces made
unsafe by the
environment, and
Unsafe work practices.

29. 29
Hazard – Exposed Electrical Parts
Cover removed from wiring or breaker box

30. 30
Control – Isolate Electrical Parts
• Use guards or
barriers
• Replace covers
Guard live parts of electric
equipment operating at 50 volts or
more against accidental contact

31. 31
Control – Isolate Electrical Parts -
Cabinets, Boxes & Fittings
Conductors going into them must be protected,
and unused openings must be closed

32. 32
Control – Close Openings
• Junction boxes, pull
boxes and fittings must
have approved covers
• Unused openings in
cabinets, boxes and
fittings must be closed
(no missing knockouts)
Photo shows violations
of these two requirements

33. 33
Hazard - Overhead Power Lines
• Usually not insulated
• Examples of equipment that
can contact power lines:
 Crane
 Ladder
 Scaffold
 Backhoe
 Scissors lift
 Raised dump truck bed
 Aluminum paint roller

34. 34
Control - Overhead Power Lines
• Stay at least 10 feet away
• Post warning signs
• Assume that lines are
energized
• Use wood or fiberglass
ladders, not metal
• Power line workers need
special training & PPE

35. 35
Hazard - Inadequate Wiring
• Hazard - wire too small for the current
• Example - portable tool with an
extension cord that has a wire too
small for the tool
 The tool will draw more current than
the cord can handle, causing
overheating and a possible fire
without tripping the circuit breaker
 The circuit breaker could be the right
size for the circuit but not for the
smaller-wire extension cord
Wire Gauge
WIRE
Wire gauge measures
wires ranging in size from
number 36 to 0 American
wire gauge (AWG)

36. 36
Control – Use the Correct Wire
• Wire used depends on operation, building materials,
electrical load, and environmental factors
• Use fixed cords rather than flexible cords
• Use the correct extension cord
Must be 3-wire type and designed for hard or extra-hard use

37. 37
Hazard – Defective Cords & Wires
• Plastic or rubber
covering is
missing
• Damaged
extension cords
& tools

38. 38
Hazard – Damaged Cords
• Cords can be damaged by:
Aging
Door or window edges
Staples or fastenings
Abrasion from adjacent
materials
Activity in the area
• Improper use can cause
shocks, burns or fire

39. 39
Control – Cords & Wires
• Insulate live wires
• Check before use
• Use only cords that are 3-wire type
• Use only cords marked for hard or
extra-hard usage
• Use only cords, connection devices,
and fittings equipped with strain
relief
• Remove cords by pulling on the
plugs, not the cords
• Cords not marked for hard or extra-
hard use, or which have been
modified, must be taken out of
service immediately

40. 40
Permissible Use of Flexible Cords
Stationary equipment-to
facilitate interchange
DO NOT use flexible wiring where
frequent inspection would be difficult
or where damage would be likely.
Flexible cords must not be . . .
• run through holes in walls, ceilings,
or floors;
• run through doorways, windows, or
similar openings (unless physically
protected);
• hidden in walls, ceilings, floors,
conduit or other raceways.

41. 41
Grounding
Grounding creates a low-
resistance path from a tool
to the earth to disperse
unwanted current.
When a short or lightning
occurs, energy flows to the
ground, protecting you
from electrical shock,
injury and death.

42. 42
Hazard – Improper Grounding
• Tools plugged into
improperly grounded
circuits may become
energized
• Broken wire or plug on
extension cord
• Some of the most
frequently violated OSHA
standards

43. 43
Control – Ground Tools & Equipment
• Ground power supply systems,
electrical circuits, and electrical
equipment
• Frequently inspect electrical
systems to insure path to ground is
continuous
• Inspect electrical equipment before
use
• Don’t remove ground prongs from
tools or extension cords
• Ground exposed metal parts of
equipment

44. 44
Control – Use GFCI (ground-fault
circuit interrupter)
• Protects you from shock
• Detects difference in current
between the black and white wires
• If ground fault detected, GFCI
shuts off electricity in 1/40th of a
second
• Use GFCI’s on all 120-volt, single-
phase, 15- and 20-ampere
receptacles, or have an assured
equipment grounding conductor
program.

45. 45
Control - Assured Equipment
Grounding Conductor Program
Program must cover:
All cord sets
Receptacles not part of a building or structure
Equipment connected by plug and cord
Program requirements include:
Specific procedures adopted by the employer
Competent person to implement the program
Visual inspection for damage of equipment
connected by cord and plug

46. 46
Hazard – Overloaded Circuits
Hazards may result from:
• Too many devices plugged
into a circuit, causing heated
wires and possibly a fire
• Damaged tools overheating
• Lack of overcurrent
protection
• Wire insulation melting, which
may cause arcing and a fire in
the area where the overload
exists, even inside a wall

47. 47
Control - Electrical Protective Devices
• Automatically opens circuit if
excess current from overload
or ground-fault is detected –
shutting off electricity
• Includes GFCI’s, fuses, and
circuit breakers
• Fuses and circuit breakers
are overcurrent devices.
When too much current:
 Fuses melt
 Circuit breakers trip
open

48. 48
Power Tool Requirements
• Have a three-wire cord with
ground plugged into a
grounded receptacle, or
• Be double insulated, or
• Be powered by a low-voltage
isolation transformer

49. 49
Tool Safety Tips
• Use gloves and appropriate footwear
• Store in dry place when not using
• Don’t use in wet/damp conditions
• Keep working areas well lit
• Ensure not a tripping hazard
• Don’t carry a tool by the cord
• Don’t yank the cord to disconnect it
• Keep cords away from heat, oil, & sharp edges
• Disconnect when not in use and when
changing accessories such as blades & bits
• Remove damaged tools from use

50. 50
Preventing Electrical Hazards - Tools
• Inspect tools before use
• Use the right tool
correctly
• Protect your tools
• Use double insulated
tools
Double Insulated marking

51. 51
Temporary Lights
Protect from contact and damage, and don’t
suspend by cords unless designed to do so.

52. 52
Clues that Electrical Hazards Exist
• Tripped circuit breakers or
blown fuses
• Warm tools, wires, cords,
connections, or junction
boxes
• GFCI that shuts off a circuit
• Worn or frayed insulation
around wire or connection

53. 53
Lockout and Tagging of Circuits
• Apply locks to power source after de-
energizing
• Tag deactivated controls
• Tag de-energized equipment and
circuits at all points where they can be
energized
• Tags must identify equipment or
circuits being worked on

54. 54
Safety-Related Work Practices
To protect workers from electrical shock:
Use barriers and guards to prevent
passage through areas of exposed
energized equipment
Pre-plan work, post hazard warnings
and use protective measures
Keep working spaces and walkways
clear of cords

55. 55
Safety-Related Work Practices
• Use special insulated tools
when working on fuses with
energized terminals
• Don’t use worn or frayed
cords and cables
• Don’t fasten extension cords
with staples, hang from nails,
or suspend by wire.

56. 56
Preventing Electrical Hazards -
Planning
• Plan your work with others
• Plan to avoid falls
• Plan to lock-out and tag-
out equipment
• Remove jewelry
• Avoid wet conditions and
overhead power lines

57. 57
Avoid Wet Conditions
• If you touch a live wire or other
electrical component while standing
in even a small puddle of water you’ll
get a shock.
• Damaged insulation, equipment, or
tools can expose you to live
electrical parts.
• Improperly grounded metal switch
plates & ceiling lights are especially
hazardous in wet conditions.
• Wet clothing, high humidity, and
perspiration increase your chances
of being electrocuted.

58. 58
Preventing Electrical Hazards - PPE
• Proper foot protection
(not tennis shoes)
• Rubber insulating
gloves, hoods, sleeves,
matting, and blankets
• Hard hat (insulated -
nonconductive)

59. 59
Preventing Electrical Hazards –
Proper Wiring and Connectors
• Use and test GFCI’s
• Check switches and
insulation
• Use three prong plugs
• Use extension cords only
when necessary & assure
in proper condition and
right type for job
• Use correct connectors

60. 60
Training
• Deenergize electric equipment before
inspecting or repairing
• Using cords, cables, and electric tools that
are in good repair
• Lockout / Tagout recognition and procedures
• Use appropriate protective equipment
Train employees working with electric
equipment in safe work practices, including:

61. Prevention
• Proper design, installation, maintenance of electric
devices
• Educating the public regarding electrical devices
awarness
• Keep electrical gadgets out of children’s reach
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62. 62
Summary – Hazards & Protections
Hazards
• Inadequate wiring
• Exposed electrical parts
• Wires with bad insulation
• Ungrounded electrical systems
and tools
• Overloaded circuits
• Damaged power tools and
equipment
• Using the wrong PPE and tools
• Overhead powerlines
• All hazards are made worse in
wet conditions
Protective Measures
• Proper grounding
• Use GFCI’s
• Use fuses and circuit
breakers
• Guard live parts
• Lockout/Tagout
• Proper use of flexible
cords
• Close electric panels
• Training

63. 63
Summary
Electrical equipment must be:
 Listed and labeled
 Free from hazards
 Used in the proper manner
If you use electrical tools you must be:
 Protected from electrical shock
 Provided necessary safety equipment

64. What happens during electric shock?
• Shocking sensations. Numbness or tingling.
• A change in vision, speech, or in any
sensation
• Makes you fall down leads to injuries
• Muscle contraction
• Seizures
• Burns, open wounds
• Fractures
• Tissue death (necrosis)
• Respiratory/Heart/Kidney failure
• Unconsciousness
• Death
64

65. Steps to follow
• Look first. Don't touch.
• Do NOT touch the victim with your bare hands,
or the electric current will pass through you
• If you are barefoot, stand on some clothes or
any hand non-conductive material like wood or
paper. Make sure you are not standing on
anything that is wet.
•
65

66. Turn off the source of
electricity
• First step is to switch off the current source
• Otherwise, move the source using a wooden stick
66

67. Check for signs of circulation
(breathing, coughing or movement and
heart function)
• Check for breathing and circulation (ABC of first aid)
• No breathing, do Cardio pulmonary resuscitation (CPR)
• Call 108
• If breathing, do a physical examination
• Re-establish vital functions
• Supportive care must be provided (Recovery position )
67

68. Prevent shock
• Keep the victim in the shock position
• Head down and legs rise
68