Transcript Fire Extinguisher Training and Education

Electrical
Safety for
NonElectrical
Workers
(Unqualified)
North Slope
Training Cooperative
© North Slope Training Cooperative—revised May 2012. All rights reserved.
NSTC-10
Course Overview
2
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Administration and
Safety
Emergency Procedures
Restrooms/Breaks/Smoking
Safety Minute
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3
Introductions
Name
Company and/or position
Experience working in areas where there are
potential hazards from energized equipment,
or power tools.
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4
Goal
To provide non-electrical (unqualified)
employees with the knowledge to recognize
electrical hazards and take appropriate
measures to protect themselves against injury
or death.
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5
Objectives
Distinguish between an affected person,
unqualified person, and qualified person as it
pertains to electrical safety.
List the potential electrical injuries/hazards
related to using power tools and working
around energized equipment.
Explain basic electrical concepts that are
important to understanding why electricity is
dangerous.
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6
Objectives
Explain safe work practices for using power
tools/equipment and working around
energized equipment.
Explain the general rules for responding to an
electrical emergency.
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7
Standards and Terms
8
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Electrical Standards
9
OSHA 29 CFR 1910.331-333: Subpart S:
Safety Related Work Practices for Qualified
and Unqualified Persons
OSHA 29 CFR 1926 Subparts I and K
National Electrical Code (NFPA 70)
Alaska Safety Handbooks (ASH & BP ASH)
ASH, pages 22-24; 28-29;
BP ASH, pages 59-61; 214
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Key Terms
10
What are the correct definitions of the following
terms and why are they important? Which of
these definitions fit your job responsibilities?
Affected Employee
Unqualified Person
Qualified Person
ASH, page 189, 195;
BP ASH, page 237, 244
OSHA 29 CFR 1910.331(a)
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Basic Electrical
Concepts
11
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How Electricity Works
When you turn on a light switch, current flows
from the generating source through a
conductive material (wires) to the area of
demand or load (light bulb).
Current will only flow if a complete path or circuit
is provided from the source, through the load,
and back to the source.
The electrical pressure that causes current to
flow is voltage. A conductor connected to a
power (voltage) source is said to be energized.
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12
Electricity Flow
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13
Simple Electrical Circuit
Open
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14
Simple Electrical Circuit
Closed
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15
Ohm’s Law
V= IR
For electrons to move in a particular direction, a
potential difference must exist between two points
within the circuit. This difference is measured in
volts (V).
Current (I), the continuous movement of electrons
past a given point, is measured in amperes.
All conductors resist the flow of current, some
more than others. Resistance (R) is measured in
ohms.
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16
Types of Current
Direct current (DC) flows in one direction with
constant pressure (voltage).
Examples: battery-operated tools or equipment;
motors used in special process applications
Alternating current (AC) periodically reverses
it’s direction of flow according to a cycle. In the
U.S., AC current is 60 cycles per second.
Examples: circuits for lights, appliances, tools and
equipment
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Conductors
Electrical conductors are low resistance
materials which readily allow electrons to pass
through.
Examples are copper, aluminum, iron, steel,
water with impurities, electrolytes, and concrete.
Because all conductors resist electron flow to
some extent, when the current overcomes the
resistance, it creates heat.
The photo above shows copper wires covered
by a glass insulator.
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18
Insulators
Because conductors get hot, they need to be
insulated to prevent fires.
Materials such as glass, ceramics, plastics,
rubber-like polymers, and porcelain have a
natural resistance to electrical flow and make
good insulators.
Copper wires sheathed in plastic and
enclosed in an aluminum cable
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Copper
wires
sheathed
in plastic
19
Electrical Safety Devices
Circuit breakers and fuses: Automatic
tripping devices which control the amount
of current flowing in the circuit and prevent
overloaded circuits which could cause fires.
They are designed to protect the equipment
from damage.
Ground fault circuit interrupter (GFCI): A
safety device which detects current leakage
from a circuit to ground (ground fault) and
shuts off the current. It is designed to
protect the person not the equipment.
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20
Bonding
21
Bonding is the process of connecting two or more
conductive objects to each other by means of a conductor
to minimize potential differences between conductive
objects. Bonding equalizes the potential between objects.
BP ASH, pages 198-199; 238
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Grounding
22
Grounding is the process of connecting one or more
conductive objects to the ground to minimize potential
differences between objects and the ground. Grounding
dissipates an electric charge to ground.
BP ASH, pages 198-199; 241
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Bonding and Grounding
This is an example of grounding two objects with the
earth and bonding them to each other.
BP ASH, pages 198-199; 238; 241
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23
Electrical Hazards
and Injuries
24
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Potential Electrical
Hazards
Contact with overhead transmission lines
Defective insulation – exposed wiring or electrical parts
Overloaded circuits
Ungrounded or improperly grounded circuits
Wet conditions
Defective tools and equipment
Flammable atmosphere
Inadequate wiring
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25
Electrical Shock
Electrical shock occurs when a person’s body
completes an electrical circuit by touching:
an energized wire and an electrical ground.
an energized wire and another wire of a different
voltage.
a metallic part that is “hot” because it’s touching
an energized wire and is in contact with the
ground.
A energized wire while perspiring or standing on
wet ground.
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26
Electrical Shock
Electrical shock can cause:
a slight tingling or total immobility
severe burns
internal bleeding, tissue, and muscle damage
cardiac arrest and death (electrocution)
Electrical shock is often the beginning of a
chain of events which may include falls, cuts,
broken bones.
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27
Electrical Shock
The severity of injury from electrical shock
depends on the:
amount of current flowing through the body.
amount of voltage.
path of the current through the body.
length of time the body is part of the circuit.
resistance of the skin.
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28
Arc Flash or Blast
Arc flashes and/or blasts occur when high amperage
currents jump from one conductor to another through
air, generally during opening or closing circuits or when
static electricity is present.
Fire or explosion can occur if the
atmosphere contains a flammable or
explosive mixture.
An arc flash or blast can result in
burns, blindness, hearing loss, and
shrapnel wounds.
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Safe Work Practices
30
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Equipment Inspections
31
Inspect all equipment, appliances,
extension cords or plug-connected hand
tools for any sign of damage or missing
parts prior to use.
Tag defective appliances, tools, and
extension cords, and turn them in for
repair.
When electric-driven equipment
becomes unsafe to operate, it shall be
locked and tagged out immediately.
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ASH, page 22
BP ASH, page 59
Equipment Repairs
32
Only qualified and
authorized personnel shall:
repair, adjust, or install
electrical equipment and
wiring systems.
make repairs to extension
cords and cords on electrical
tools.
ASH, page 22
BP ASH, page 59
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Extension Cords
Use only three-wire, grounded, extension
cords.
Electrical cables and/or extension cords
should be run overhead and not laid on the
ground or deck (ASH, page 24; BP ASH, page 60).
High current equipment or appliances should
be plugged directly into a wall outlet
whenever possible.
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33
Extension Cords
All extension cords should be plugged into:
a GFCI outlet,
a GFCI built into the cord, or
a GFCI adapter used between the wall outlet
and the cord plug.
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34
Power Tools
35
All electrical equipment and tools must have
an on and off switch and may not be turned
on or off by plugging or unplugging the
supply cord at the power outlet.
All portable electric tools shall be used with
ground fault circuit interrupters (GCFI) or be
included in an assured grounding program.
Avoid contact between two connections on a
battery.
ASH, page 22
BP ASH, page 59
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Power Tools and
Equipment
36
Motor overloads may be reset once after an
Operator has checked the motor for any
unusual conditions such as hot bearings or
motor. Notify facility electrician of the trip.
Motor starts per hour shall not exceed the
manufacturer’s specifications.
Any feeder or branch circuit breaker trips
shall be brought to the attention of the
Supervisor or facility electrician.
ASH, page 23
BP ASH, page 60
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Lighting
37
A Hot Work Permit is required to install or use
non-explosion proof temporary lighting in a
classified area.
All portable lights shall be used with ground
fault circuit interrupters (GCFI) or be included
in an assured grounding program.
Low voltage lights (50 volts or less) may be
used in lieu of lights with GCFI.
Use approved lighting in wet and classified
areas
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ASH, page 22
BP ASH, page 59
Working Near Energized
Equipment
38
Portable ladders, used for electrical
work, shall have non-conductive side
rails.
Equipment operating within 15 feet of
any un-insulated power distribution
system line, structure, guywire or
switch yard requires prior clearance by
the appropriate Company Supervisor.
ASH, pages 23-24
BP ASH, pages 60-61
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Working Near Energized
Equipment
39
Maintain minimum 4 foot NEC
required clearances in front of
all switchgear and motor
control centers for access.
If these clearances are not
present, the switchgear must
be appropriately marked with
warning labels.
These spaces are not intended
for storage areas and must be
kept clear.
ASH, page 22
BP ASH, page 59
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Avoiding Other Electrical
Hazards
40
Avoid overloading circuits by
plugging in multiple appliances
(microwave ovens, toasters, space
heaters, coffeepots) into the same
outlet.
Remove jewelry and other
conductive objects before starting
work.
ASH, pages 6, 11
BP ASH, pages 30, 38
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Electrical Lockout
Tagout
41
If an employee can be exposed to
contact with energized electrical
equipment, the circuits energizing the
parts shall be isolated by lockout tagout
procedures (OSHA 1910.333(b)(2) ).
Only authorized personnel may perform
lockout and tagout work on electrical
equipment.
Affected employees will be notified when
lockout and/or tagout activities are being
performed in their work area.
ASH, page 189
BP ASH, pages 237
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Personnel Restrictions
42
Only authorized personnel shall be
permitted in electrical distribution
switchgear rooms and enclosures.
Equipment operating within 15 feet
of any un-insulated power
distribution system line, structure,
guy wire, or switch yards requires
prior clearance by the appropriate
Company Supervisor.
ASH, pages 23-24
BP ASH, pages 59-60
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Personnel Restrictions
43
Only a qualified electrician may bring
a conductive object closer than 15
feet to unguarded, energized
overhead lines.
Power distribution switchgear shall
be operated only by qualified
personnel.
Review the electrical safety
procedures in the Alaska Safety
Handbooks.
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ASH, pages 23-24
BP ASH, pages 59-60
Responding to an
Electrical Emergency
44
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Follow the Emergency
Action Plan
Remain calm and keep your
distance.
Turn off the power.
Call for help immediately.
Do not touch the victim.
Trained personnel may
administer First Aid or CPR
when it is safe to touch the
victim.
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45
Fire Extinguishers
46
Approved fire extinguishers should
be provided near electrical breaker
panels and distribution centers.
Water-type extinguishers are not
intended for use on electrical fires
and shall not be located closer
than 50 feet from electrical
equipment.
Do not use a fire extinguisher
unless you are trained to do so.
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ASH, pages 11-12
BP ASH, pages 35-36
Summary
Standards and Terms
How Electricity Works
Electrical Hazards and Injuries
Safe Work Practices
Responding to Electrical Emergencies
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47