The document discusses electrical hazards and safety. It identifies common causes of electrocution such as contact with overhead power lines, live circuits, and defective equipment. Electrical injuries can be direct, such as electrocution or shock, or indirect like falls or fires. The severity of shock depends on factors like current path and duration. Overhead power lines pose a hazard to equipment like cranes and ladders. Workers must be trained in safety practices like lockout/tagout procedures and PPE inspection to avoid energized circuits."

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Electrical Hazards

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Causes of
Electrocution Fatalities
• Contact with Overhead Power lines
• Contact with Live Circuits
• Not following Lock/Tagout procedures
• Poorly Maintained Extension Cords
• Defective Power Tools

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Electrical Injuries
There are three direct and two indirect types of
electrical injuries:
• Direct:
Electrocution or death due to electrical shock
Electrical shock
Burns
• Indirect:
Falls
Fire

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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

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

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It’s Your Job to Know!
 Know the hazards of electricity
 Know the equipment
 Use Safe Work Practices
 Inspect your Personal Protective
Equipment (PPE) before each use
 Don’t work on energized circuits
without permission

7. What are the levels of effect of current?
AC current (mA) Effect on human body
1 Slight tingling sensation
2-9 Small shock
10-24 Muscles contract causing you to freeze
25-74 Respiratory muscles can become
paralysed; pain; exit burns often visible
75-300 Usually fatal; ventricular fibrillation; entry &
exit wounds visible
>300 Death almost certain; if survive will have
badly burnt organs and probably require
amputations
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8. A welding incident…
• Assistant hands welder a metal object.
Resultant current is 35 mA
I = V/R = 67/1900 = 35 mA
Result = Assistant survived but welder died
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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

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• Special Training is required for work on
electrical equipment. Such training is for
Authorized Employees and it covers:
–Safe Work Practices
–Isolation of Electrical Sources
–Test Equipment
–Tools & PPE
• Only Authorized Employees may conduct
electrical work
Caution

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Control Devices
Control circuit devices such as…
–push buttons
–selector switches
–interlocks
… may not be used as the sole
means for de-energizing circuits
or equipment.

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How it works

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Are these safe practices?

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Lock & Tag
• Lock & Tag all Sources
– Place Lock & Tag on each disconnecting
means used to de-energize circuits
– Attach lock to prevent operating the
disconnecting means
– Place Tag with each lock
Note: Only the person who places the lock may remove it.

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Lockout Devices

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If a Lock cannot be applied…
• A tag used without a lock must be
supplemented by at least one additional
safety measure that provides a level of safety
equal to that of a lock.
• Examples:
– Removal of an isolating circuit element
such as a fuse
– Blocking of a controlling switch
– Opening of an extra disconnecting device.

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Tagout
There many different kinds of tags and Lockout devices.

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Release Stored Energy
• Stored electric energy must be released
before starting work.
– Discharge all Capacitors
–Short-Circuit & Ground all high
capacitance elements

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Alerting others of hazards
Use barricades to prevent or limit access to
work areas with un-insulated energized
conductors or circuit parts.
Use safety signs, safety symbols, or accident
prevention tags to warn others about electrical
hazards which may endanger them.
If signs and barricades do not provide sufficient
warning and protection from electrical hazards,
an attendant shall be stationed to warn and
protect employees.

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Electrical Tools
and Cords

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Portable Electric Tools
& Cords
• Portable equipment must be handled in a
manner which will not cause damage.
• Flexible electric cords connected to
equipment may not be used for raising or
lowering the equipment.
• Flexible cords may not be fastened with
staples or otherwise hung in such a fashion
as could damage the outer jacket or
insulation.

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Tools & Equipment
– Use insulated tools or handling equipment
when working near exposed energized
conductors or circuit parts.
– Use fuse handling equipment to remove or
install fuses when the fuse terminals are
energized.
– Ropes and handlines used near exposed
energized parts must be nonconductive.

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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

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

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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

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Always remember…
It’s your life!
“A tree trimmer was electrocuted
when he touched an overhead
electrical line while descending a
palm tree…”
“An employee was
electrocuted while working
on an A/C unit…”