ELECTRICAL SAFETY
FOR
INDUSTRIAL HYGIENISTS
New England AIHA
June 16, 2015
Presented by:
Paul J. Webb, CIH, CSP
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Why is it important to have a working knowledge
of electrical safety?
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ELECTRICAL SAFETY
• Electrical safety violations consistently make OSHA’s top
10 list of cited standards.
• Electrical hazards are not always obvious but can result
in serious injury or death.
• Because of the risk and common presence in
workplaces, all health and safety professionals should
have a basic knowledge of this hazard.
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ELECTRICAL SAFETY Three reasons why industrial hygienists should feel
comfortable developing electrical safety skills:
1. A basic understanding of electrical principles is
sufficient
2. An accurate assessment of risk is critical
3. Industrial hygienists are already skilled in assessing risk
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What actions and resources are needed to develop
a working knowledge of electrical safety?
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ACTIONS AND RESOURCES
• Basic electrical principles, hazards, and their effects
• NFPA 70E and OSHA subpart S regulations
• Practice at your level of knowledge
• Recognize when it is necessary to rely on the expertise
of other professionals
• Use a team approach to manage electrical safety
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WHAT IS ELECTRICITY?
• An inexact term
• Easier to describe what
it does than what it is
• It’s the presence and
flow of electric charge
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WHAT IS ELECTRICITY?
Electricity is characterized by the interaction of these five
physical effects:
1.
2.
3.
4.
5.
Electric charge
Electric current
Electric field
Electric potential
Electromagnetism
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WATER AND ELECTRICITY ANALOGY
“Pressure” - Force is needed to move both water
and electrical current
“Flow Rate” - The larger the pipes and wires, the
more water and electric current is carried.
“Friction” - Both water and electric current flow
from high to low pressure to complete a circuit.
• Controlling devices, such as faucets and
switches, are used to start and stop flow.
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WHAT IS ELECTRICITY?
Dielectric field (insulation) strength
• The ability of material to provide a protective
barrier to stop (resist) the flow of electric
energy
• Basis for electric protective measures
• Insulators have high dielectric strength
• Conductors have low dielectric strength
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ELECTRICAL UNITS
Resistance
• Conditions which retard current flow
• All materials exhibit some resistance
• Ohm (Ω) is the unit for resistance
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ELECTRICAL UNITS
Resistance
• Conductors are materials that allow current to
flow with minimal loss of energy
• Conductors have LOW resistance
Examples: aluminum, copper, water
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ELECTRICAL UNITS
Resistance
• Insulators are materials that impede current
flow
• Insulators have HIGH resistance
Examples: Rubber and glass
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SKIN RESISTANCE
• Up to a point, human skin is an insulator
• Dry skin will provide a much higher resistance
• Sweaty and wet skin lowers electrical
resistance
•
•
Dry skin: 100,000 ohms
Wet or broken skin: 1,000 ohms
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ELECTRICAL UNITS: VOLTAGE
Voltage (“pressure”)
• Also known as potential difference or electrical
potential
• The amount of work needed to move a charge
between two points
• Units = Volts (V)
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ELECTRICAL UNITS: CURRENT
Current (“flow rate”)
• Current is electron flow past a certain point in a
given period of time
• In water terms, it is similar to the flow of
gallons per minute.
• Units = Amps (I)
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ELECTRICAL UNITS
Water in a pipe Direct Current in
a Wire
Pressure
Flow
Friction
Voltage (V)
Current (I)
Resistance (R)
Electric Unit
Volt
Amp
Ohm
Key Points
• Water and electricity flow in a loop or circuit
• Both flow in any available path from high to low energy states
• Proper sizing of pipes and wires is necessary to match pressure and
flow
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WHAT IS ELECTRICITY?
• Electricity is delivered in three ways:
1. Electric sparks through electro-static
discharge
2. Direct Current (DC) circuits
3. Alternating Current (AC) circuits
• Regardless of delivery, the circuit or loop
concept is a useful way to think about electrical
principles and its hazards.
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ELECTRICAL HAZARDS
AND THEIR EFFECTS
ELECTRICAL SAFETY FACTS
• On average:
One worker is electrocuted on the job every day
One person is electrocuted in the home every 36
hours
• Electrical incidents are far more likely to be
fatal than other types
• OSHA’s top 25 most-cited serious violations
include electrical safety violations
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ELECTRICAL SAFETY FACTS
• For every 300,000 at-risk behaviors, 300 recordable
injuries, 30 LTI, and 1 fatality.
• Electricians suffer the highest number of electrocutions
per year at 34% of total deaths
• Reason was working with or near energized parts
without using proper safety procedures
• The cost of each major electrical incident can average
between $1-4 million
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TYPES OF ELECTRICAL INJURIES
There are four main types of electrical injuries:
Electrocution (death due to electrical shock)
Electrical shock (non-fatal)
Burns
Falls
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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
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ELECTROCUTION
• Electrocution occurs when an electric shock is fatal
• Currents >75 mA can cause ventricular fibrillation and
death
• 12% of electrocutions result from contact with 120 Volts
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ELECTRIC CONTACT
• Electric contact normally occurs in one of three
ways - when an individual is in contact with the
ground and contacts:
1. Both wires of an electric circuit, or
2. One wire of an energized circuit and the ground, or
3. A metallic part that has become energized by
contact with an energized conductor
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ELECTRIC CONTACT
• Touch Potential – potential difference between
what is being stood on and what is being
touched
• Step Potential – potential difference between
your feet
• Wearing Electrical Hazard (EH) rated shoes
provides some protection.
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HAZARDS OF ELECTRICITY
BODILY EFFECT
DIRECT CURRENT (DC)
60 Hz AC 10 kHz AC
Slight sensation
felt at hand(s)
Men = 1.0 mA
Women = 0.6 mA
0.4 mA
0.3 mA
7 mA
5 mA
Threshold of
perception
Men = 5.2 mA
Women = 3.5 mA
1.1 mA
0.7 mA
12 mA
8 mA
Painful, unable
to let go of wires
Men = 76 mA
Women = 51 mA
16 mA
75 mA
10.5 mA 50 mA
75 mA
Possible heart
fibrillation
after 3 seconds
Men = 500 mA
Women = 500 mA
100 mA
100 mA
Fatal Threshold
Current
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HAZARDS OF ELECTRICITY
Effects on the body depend on:
• Amount of electrical current
• Duration of contact
• Body mass
• Moisture of body
• Current path through the body
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ELECTRICAL BURNS
•
•
•
Most common shockrelated, nonfatal injury
Occurs when you touch
electrical wiring or
equipment that is
improperly used or
maintained
Typically occurs on the
hands
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ARC FLASH HAZARD
• Arc flash occurs when an electric current passes through
air between ungrounded conductors or between
ungrounded conductors and grounded conductors.
• Temperatures can reach 35,000 ◦F. Exposures to these
extreme temperatures burn the skin directly and cause
ignition of clothing, which adds to the burn injury.
• Arc flash burns account for the majority of hospital
admissions due to electrical incidents.
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ARC BLAST HAZARDS
• An Arc Blast occurs when extreme temperature of the
arc causes an explosive expansion of the surrounding air
and the metal in the arc path.
• The expansion results in high pressures, sound,
ultraviolet light, and shrapnel.
• Pressures can exceed hundreds or even thousands of
pounds per square foot, knocking workers off ladders,
rupturing eardrums and collapsing lungs.
• Molten metal is expelled form the arc at speeds
exceeding 700 mph, enough for shrapnel to penetrate
the body.
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STRAY VOLTAGE
• Stray voltage includes all occurrences of unwanted
excess electricity
• Caused by a failure of bonding metal equipment to
ground
• People or animals make contact and create step and
touch potentials, sometimes with fatal outcomes
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TOUCH POTENTIAL
Swimmer, 8, dies after contact with electric wire,
BROWNSVILLE, Texas
Associated Press. June 2, 2011
An 8-year-old girl who had been swimming at a neighbor's
pool in South Texas has died after touching an exposed
electrical wire.
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STEP POTENTIAL
Con Ed to Pay $7.2 Million in Electrocution Case
By IAN URBINA and SABRINA TAVERNISE
New York Times, November 24, 2004
Nearly a year after a woman was electrocuted while
walking her dogs on a wet East Village street,
Consolidated Edison has agreed to pay her family
more than $6.2 million and to set up a $1 million
scholarship fund in her name at Columbia
University, where she was a doctoral student….
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STEP POTENTIAL
Stray NStar wires kill dog in Allston
By Megan Tench, Boston Globe | March 2, 2005
A one-year old dog died yesterday after stepping in a
muddy area where a live electrical wire was buried on
Western Avenue in Allston.
Cause:
Exposed wires from light pole (removed): The
company failed to shut off power to the site and cap
wires that remained exposed under the surface.
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ELECTRICAL STANDARDS
Applicable Standards include:
• 29 CFR 1910 OSHA Standards for General Industry: Subpart
S—Electrical
• 29 CFR 1910.269 OSHA Standard for Electric Generation,
Transmission, and Distribution
• NFPA 70E (2015): Standard for Electrical Safety in the
Workplace
• NFPA 70 – National Electric Code (NEC)
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EXPOSURE GROUPS
Two potential exposure groups:
1. Electrically qualified persons
• Applicable standards: OSHA and NEC, and NFPA 70E
2. Building occupants (electrically unqualified
persons)
• Applicable standards: OSHA Subpart S
Employer has the legal obligation to ensure that the electrical
system in the workplace is maintained to code and that the system
is only worked on by electrically qualified persons.
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ELECTRICAL SYSTEM DESIGN
Design safety standards for electrical systems are covered
in the NEC with and OSHA Subpart S standards 1910.302
through 1910.308
Regulatory and Legal Expectation:
1. General employee/occupant protected through
correct installation, use, maintenance, and isolation
of live parts.
2. No electrical hazard under normal operating
conditions.
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ACCESS AND IDENTIFICATION
I N A C C U R AT E , C O N F U S I N G , O R
INSUFFICIENT LABELING OF
CIRCUITS
BLOCKED ACCESS TO
S E R V I C E PA N E L
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MISUSE OF EQUIPMENT
Using consumer-rated
electrical appliances for
commercial or industrial use
Examples includes fans and
coffee makers.
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FAILURE TO GUARD LIVE PARTS
Service panels – uncovered circuit breaker
openings
Exposed wires
Damaged wire insulation
Unguarded fluorescent lighting
Unguarded receptacles
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FAILURE TO GUARD LIVE PARTS
UNGUARDED LIGHTING
SOCKET
U N G UA R D E D R E C E P TA C L E S
To prevent accidental contact, OSHA requires all energized conductors within 8
feet of the floor or working surface to be guarded.
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INCORRECT/DAMAGED WIRING CONNECTIONS
Reversed Polarity
Open Ground
Open Hot
Open Neutral
Correct Wiring Tester
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MISUSE OF EXTENSION CORDS
Common violation:
The permanent use
of an electrical
cord designed for
temporary use
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GROUNDING HAZARDS
Failure to properly ground
equipment:
The 1980 MGM Grand fire in
Las Vegas that resulted in 85
fatalities was the result of
an ungrounded deli
machine.
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FAILURE TO GROUND IN WET CONDITIONS
Motors and tools used in wet and conductive locations are
some examples of equipment that must be grounded.
Corrected by:
• Using double-insulated tools
• GFCIs on all circuits exposed to wet or conductive
conditions
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NFPA 70E
• Consensus safety standard published by NFPA
primarily to assist OSHA in preparing electrical
safety standards.
• OSHA bases its electrical safety standards on
NFPA 70E.
• OSHA provides the “shall” while NFPA provides
the “how.”
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NFPA 70E
• In 2015, the NFPA released the tenth edition of
the 70E standard for electrical safety in the
workplace based on the 2014 NFPA 70 (NEC)
Code.
• The standard is consists of three chapters and
includes separate Informative Annexes from A
to P.
• NFPA 70E serves as a framework for managing
electrical safety.
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NFPA 70E - SCOPE
Covered activities:
The installation, inspection, operation,
maintenance, and demolition of electric
conductors, electric equipment, signaling and
communications conductors and equipment, and
raceways.
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NFPA 70E
• Standard applies to any work on electrical systems.
• 2015 Edition focuses on risk rather than hazard.
Risk A combination of the likelihood of occurrence of injury or
damage to health and the severity of injury or damage to
health that results from a hazard.
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ELECTRICAL RISK ANALYSIS
• Required before any work on live parts above 50 volts
within the limited approach boundary
• Determines appropriate safety-related work practices
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NFPA 70E – CHAPTER 1
Chapter 1 of this standard is divided into five articles.
1. Article 100 provides definitions for terms used in the
standard
2. Article 105 provides for application of safety-related work
practices.
3. Article 110 provides general requirements for electrical
safety-related work practices.
4. Article 120 provides requirements for establishing an
electrically safe work condition.
5. Article 130 provides requirements for work involving
electrical hazards.
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NFPA 70E – CHAPTER 2
• Chapter 2 of this standard covers practical safety-related
maintenance requirements for electrical equipment and
installations in workplaces.
• It is left to the employer to choose from the various
maintenance methods available to satisfy the
requirements of Chapter 2.
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NFPA 70E – CHAPTER 3
Chapter 3 is divided into articles.
• Article 300 applies generally.
• Article 310 applies to electrolytic cells.
• Article 320 applies to batteries and battery rooms.
• Article 330 applies to lasers.
• Article 340 applies to power electronic equipment.
• Article 350 applies to research and development (R&D)
laboratories.
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ISOLATE AND INSULATE
• Personnel come into contact with live parts either
through the process of de-energizing or if work can only
be performed under energized conditions.
• Isolation and Insulation are the basis for personnel
protection
• Engineering and personal protective measures rely on
these two principles.
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PERSONNEL PROTECTION
• Working on or around energized parts creates an
abnormal electrical condition which triggers special
work requirements.
• These conditions are managed through a combination of
approach distances and personnel protection.
• Personnel protection includes both personal and area
protective measures: approach boundaries, PPE, tools,
and alerting techniques.
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PERSONAL PROTECTIVE EQUIPMENT (PPE)
• Rubber Products and Gloves
• Head Protection
• Eye & Face Protection
• Hearing Protection
• Foot Protection
Arc-Rated Apparel
= PPE Ensemble
(any combination of PPE and apparel)
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EQUIPMENT FOR ENERGIZED WORK
Reference: NFPA 70E (2015) 130.7
• Insulated tools, handling equipment or both are
required when working close to energized parts.
• Table 130.7(C)(15) provides further information on task
that require the use of insulated tools
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ALERTNESS
Reference: NFPA 70E (2015) 130.6(A)
• Employees shall be instructed to stay focused during
critical moments when working within the limited
approach boundary.
• Human error elimination is an emerging area of safety
practice that applies cognitive psychological principles
to high consequence tasks such as electrical work.
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OTHER PRECAUTIONS
Reference: NFPA 70E (2015) 130.6
• The employee should not perform high risk tasks if they
are distracted by fatigue, illness, or other distraction.
• Serious incidents are strongly linked to changes in scope
of work. When this occurs. Stop. Redo the job briefing
to include the changes and consider potential hazards
before continuing.
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OTHER PRECAUTIONS
Reference: NFPA 70E (2015) 130.6
• Never blindly reach into areas that could contain live
parts.
• Illumination: There shall be sufficient lighting to safely
perform the task.
• Employees shall not wear conductive articles.
• Where contact tools and materials are required, they
shall be handled in a manner that prevents arcing or
contact with live parts.
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ALERTING TECHNIQUES
Reference: NFPA 70E (2015) 130.7(E)
1. Safety Signs and Tags shall be used to warn employees
2. Barricades shall be used with safety signs and tags to
protect employees from live parts
 Barricades shall not be placed closer than the
limited approach boundary.
3. Attendant(s) shall be used if signs and barricades do
not provide sufficient warning.
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ENERGIZED ELECTRICAL WORK PERMIT
Reference: NFPA 70E (2012) 130.2(B)
• Required when working within the limited approach
boundary or the arc flash boundary of live parts that are
NOT placed in an electrically safe work condition.
• A written permit is required for work on energized parts.
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KEY POINTS
 An organization’s operations give rise to electrical hazards
that can put personnel and the general public at risk
 Failure to adequately control electrical hazards represents
significant liability to the organization
 Electrical safety is complex
 It is rare for a health and safety professional to possess all the
skills required to effectively manage electrical safety
 It’s effective management requires the skills and coordination
of multiple stakeholders
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STAKEHOLDERS
Management
 Sets safety culture and electrical safety policy
Electrical Engineers
 Design, evaluate, and specify electrical systems and components
Qualified Personnel
 Maintain electrical systems
Safety Professionals
 Develop and evaluate safety systems and provide/coordinate safety-related
training
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MODEL FRAMEWORK FOR
ELECTRICAL SAFETY MANAGEMENT
Electrical
System Design
Preventive
Maintenance
Infrastructure
Equipment
Organizational Culture
Electrical Safety
Safety
Management
Systems
People
Safety Training
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ELECTRICAL SYSTEM DESIGN

Correct design and evaluation reduces the
risk of arc flash incidents and mitigates their
effect

Evaluations include short circuit and
coordination studies to ensure sufficient
overcurrent protection.

System design includes the selection of
electrical equipment and components with
proper barriers and interlocks
Lead Stakeholder – Electrical Engineers
 Electrical engineers and other qualified personnel in coordination with the
safety professional
Reference: NFPA 70E (2015)
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PREVENTIVE MAINTENANCE
 The on-going monitoring and repair of equipment to ensure
that it performs and is being used within its design
specifications
 Develop and implement electrical task-specific procedures
Lead Stakeholder – Qualified Personnel
 Qualified personnel in coordination with electrical engineers
and safety professionals
Reference: NFPA 70E (2015)
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SAFETY MANAGEMENT SYSTEMS
Written electrical safety program aligned with management
policy and process for:
 Designating electrically qualified personnel
 Identifying high risk electrical tasks
 PPE Selection based on risk assessment
 Electrical safety program evaluation to ensure compliance
Lead Stakeholder – Safety Professional

Safety professional in coordination with management,
electrical engineers, and electrically qualified personnel
Reference: NFPA 70E (2015)
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SAFETY TRAINING
 Establish electrical safety training for all qualified and
unqualified personnel
Lead Stakeholder – Safety Professional
Safety professional in coordination with management,
electrically qualified personnel, and electrical
engineers
Reference: NFPA 70E (2015)
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SUMMARY
 Effective management of electrical hazards requires a
multi-disciplinary approach.
 Identifying and engaging stakeholders is critical to the
sustainable success of any management effort.
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IN CONCLUSION:
• Industrial hygienists are well-positioned to add electrical
safety to their tool box of skills.
• NFPA 70E provides a framework for managing electrical
safety
• Do not try to go it alone: develop of team approach to
managing electrical safety.
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