Electric Hazzard

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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…”