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ELC 119R-S Electrical Safety Refresher for Subcontract Electrical Workers


ELC 119R-S Electrical Safety Refresher for Subcontract Electrical Workers Shock Approach Boundaries Limited Approach Boundary (LAB) Level II authorization required ... – PowerPoint PPT presentation

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Title: ELC 119R-S Electrical Safety Refresher for Subcontract Electrical Workers

ELC 119R-SElectrical Safety Refresher for
Subcontract Electrical Workers
  • Introduction
  • Shock and Arc Flash
  • 2 Electrical Hazard Mitigation
  • 3 Technical work documentation (TWD)
  • 4 Safe switching procedures
  • 5 Wrap-Up

  • 300 workplace electrocutions annually
  • Estimated 20,000 shocks for every electrocution
  • 4000 injuries annually requiring days away
  • 3600 disabling electrical contact injuries
  • 10-15 workers hospitalized daily with electrical
  • 4-year average of 23 electrical events at SNL

Most Common Electrical Events at SNL
  • Short circuit of energized parts to ground
  • Workers shocked from approaching nearer than a
    safe distance from exposed live parts
  • Workers shocked from faulty equipment
  • Workers shocked from plugging/unplugging

Module 1 Shock and Arc Flash
  • The passage of electric current through the
  • body from contact with an electric circuit
  • Exposure to electrical energy may result in no
  • at all or may result in devastating damage or
  • Electrocution is death by electrical energy
  • from the passing of a high magnitude electric
  • through the body

Why Are We Susceptible to Injury by Electric
  • Our highly developed nervous system makes us
    extremely sensitive to even very small electric
  • The passage of current through the body results
    in heating of tissue
  • Each of these interactions has serious
  • consequences.

Effects of Current on the Body
Current Value Effects
lt 1 ma Barely Perceptible
1-5 ma Perceptible shock, reflex actions
5 ma GFCI trips Accepted as maximum harmless current
6-10 ma Painful shock, victim can let-go
10-20 ma Painful shock, victim can not let go
50-100 ma Ventricular Fibrillation possible
100-200 ma Ventricular Fibrillation likely
200 ma Severe burns, severe muscular contractions, chest muscles clamp the heart and stop it for the duration of the shock.
833 ma Current used by 100 watt light bulb
Effect of Current Passing Through the Body
  • Current can confuse or damage nerve control
    centers of lungs and heart
  • Heat damage caused by dissipation of energy- body
    acts as a resistor.

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Unfortunate mouse suffers a fatal phase to phase
Factors Affecting Shock Remember Ohms Law EIR
  • Current most important factor, though directly
    determined by voltage and body resistance.
  • Path of current greater chance for survival
  • if current passes through extremities only
  • Duration of Shock according to IEEE std. 80, the
    maximum safe duration can be determined by using
    t (seconds) .116/(V/R)

  • If an electrician gets a shock from a 277 volt
    light fixture, would he/she get stuck on the
    circuit? Lets assume the worker was sweating and
    use a resistance value of 10,000 ohms.
  • I E/R
  • I 277/10,000
  • I .0277 amps or 28 ma

Is He/She Stuck?
Current Value Effects
lt1 ma Barely Perceptible
1-5 ma Perceptible shock, reflex actions
5 ma GFCI trips Accepted as maximum harmless current
6-10 ma Painful shock, victim can let-go
10-20 ma Painful shock, victim can not let go
50-100 ma Ventricular Fibrillation likely
100-200 ma Ventricular Fibrillation occurs
200 ma Severe burns, severe muscular contractions, chest muscles clamp the heart and stop it for the duration of the shock.
833 ma Current used by 100 watt light bulb
Example continued
  • Lets also assume that the path of the current is
    hand to hand. How long does this person have
    before the shock could be considered fatal?
  • T .116/(V/R)
  • T .116/(277/10,000)
  • T .116/.0277
  • T 4.18 seconds!

Voltage Thresholds
  • OSHA set threshold for hazardous energy at 50
  • Hazard from applications lower than 50 are
    usually thermal not shock batteries, super
    capacitors, etc.
  • At levels greater than 600 V, skin is usually
    penetrated driving resistance down.

Entry and exit wounds
Rescuing and Treatment
  • Step 1 Check to see that the area is safe to
  • Step 2 - Call 911 immediately
  • Step 3- Rescue the victim with an insulated
    device (hot stick, rope, dry wood, etc)
  • Step 4 Begin CPR
  • Step 5 - Continue resuscitation
  • Step 6 - Get medical attention for the victim

II Arc Flash
  • A release of thermal energy from an electric arc
  • by the vaporization and ionization of materials,
  • reaching temperatures up to 35,000 F.
  • Exposure to these extreme temperatures both
  • burns the skin directly and causes ignition of
  • clothing.
  • (2004 NFPA 70E)

Nature of the Arc
  • Arc results from passing of current through air
  • Terminals vaporize and serve as conductive medium
    for ionized gasses
  • Flash can extend further than 10 from the source
  • Pressure wave caused by rapid expansion of gases
    with flying molten materials and shrapnel
  • The blast can destroy structures, and knock
    workers from ladders or across a room. The blast
    can rupture eardrums and collapse lungs.

Nature of the Arc continued
Three Factors Affecting Arc Energy
  • Available short circuit current
  • Duration of the arc
  • Distance from the arc

Burns From the Arc
  • First degree surface only. Skin is usually red
    and tender
  • Second degree blistering of the skin. Most
  • Third degree complete destruction of the skin
    with charring of tissue. Most dangerous
    susceptible to infection. Skin can not heal

First Degree Burns from a 480 Fault
Second Degree Burns from the same 480 Fault
Effects of the Arc- Burns
Arcs have ignited clothing 10 from the arc and
can be fatal when within a few feet
Accelerator Flash Incident
  • On October 11, 2004, at approximately 1115 am,
  • a subcontractor electrician working at an
    Accelerator Center received
  • serious burn injuries requiring hospitalization
  • to an electrical arc flash that occurred during
  • installation of a circuit breaker in an energized
  • 480-Volt (V) electrical panel.

Arc flash 2004
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Importance of FR Clothing60/40 blend here
From the Type A Investigation
  • Description of Injuries
  • Electrician received third degree burns on the
    face, chest, and legs and second degree burns on
    the arms, involving approximately 50 of his
    body. Because of the seriousness of his
    condition, the Board was not able to interview

Module 2 Electrical Hazard Mitigation
  1. Plan your work
  2. Analyze/identify the hazards
  3. Control the hazards
  4. Perform the work
  5. Improve the process for the next operation

1910 CFR 851 and NFPA 70E
  • All Department of Energy Facilities are
    contractually required by law follow 10 CFR 851-
    Worker Safety and Health Protection Plan
  • 851.23(a)(14) requires contractors to comply with
    NFPA 70E as a baseline.
  • 70E is the industry standard for addressing
    electrical hazards in the workplace
  • Applying 70E standards nothing more than using
    integrated safety management

  • Energized work no longer allowed at SNL unless
  • de-energizing introduces additional or increased
    hazards or is infeasible due to equipment design
    or operational limitations 70E 110.8.A.1
  • Most hazards can be controlled by insulating,
  • guarding, or by simply working de-energized

Electrically Safe Work Condition
  • First priority is to de-energize
  • Review safety plan
  • Inspect equipment, disconnect energy sources, and
    lock and tag energy sources.
  • Post barricades and signs to establish the
    limited approach and flash protection boundaries.
  • Open enclosure, identify shorting devices, and
    discharge energy-storage devices if applicable.
  • Perform Zero Energy verification Test
  • Complete work
  • When the work is completed, test circuits, remove
    tools, and test gear, perform final check, and
    close enclosure
  • NOTE Equipment is not considered de-energized
    until locked out and verified

Energized Work - provided justification
requirements (slide 34) are met
  • Strict requirements addressing worker
  • Qualified Person One who has the skills and
    knowledge related to the construction and
    operation of the electrical equipment and
    installations and has received safety training on
    the hazards involved (Electrical Safety in the
    Workplace, 2004).
  • Energized work must be authorized by Senior
    Manager Facilities Engineering- see your contract
    Sandia delegated representative (SDR)
  • Shock and Flash Hazard Analyses required. This
    can be accomplished using the table on slide 44.
    Remember 2 different hazards- shock and flash

Shock Hazard Analysis
  • Required ANYTIME a worker crosses the Limited
    Approach Boundary to exposed live parts
  • Must determine approach boundaries (Limited and
    Restricted) and required shock PPE (usually
    gloves and insulated tools)
  • Shock PPE required ANYTIME a worker crosses the
    Restricted Approach Boundary

Shock Approach Boundaries
  • Limited Approach Boundary (LAB)
  • Level II authorization required
  • Only qualified workers may cross
  • Boundary must be physically established
  • Restricted Approach Boundary (RAB)
  • No unqualified workers
  • Shock PPE required
  • Shock PPE mainly consists of insulating gloves
    and tools
  • Refer to slide 44 for LAB and RAB approach
    distances and required PPE.

Flash Hazard Analysis
  • Required ANYTIME a worker crosses the flash
    protection boundary (FPB)
  • Must determine the Flash Protection Boundary and
    the PPE required for crossing this boundary
  • PPE and distances determined from table slide 44

Arc Flash Protection
  • PPE and flash protection boundary (FPB) in CSSP
    will match that of arc flash hazard (AFH) label
    on equipment
  • If the electrical equipment is not provided with
    an AFH warning label, PPE and FPB in CSSP will be
    determined using the table in slide 44.

Exposed Live Part
Limited Approach Boundary (shock) Level II
authorization required Only qualified workers may
cross unqualified workers may cross if escorted
by qualified worker and made aware of the hazards
Boundary must be physically established
Flash Protection Boundary Distance and PPE
determined from table in slide 42 PPE required of
ANYONE inside this boundary
Restricted Approach Boundary (shock) No
unqualified workers Shock PPE required Shock PPE
mainly consists of insulating gloves and tools
Hazard Risk Categories (HRC)
  • HRC 0 Single phase circuits operating at 50-208
  • HRC 12 Three-phase circuits operating between
    120 and 600 volts
  • HRC 34 Three-phase service entrance equipment
    and switchgear operating between 120 and 600
    volts, excluding those systems with a RED, Level
    V Arc Flash Hazard label.

Hazard Risk Categories (HRC)
  • Hazard Risk Above Forty Calories All equipment
    identified with a Level V (red) Arc Flash Hazard
  • Hazard Risk Greater Than 600 volts Obtain flash
    hazard analysis.
  • Exception HRC 2 PPE shall be worn In 15 kV
    manholes. Head, face and glove protection may be
    removed during cable terminations if no other
    work is being performed in the manhole.

Boundary and PPE Table
Equipment Class HRC Flash Boundary LAB, RAB Required flash PP Required shock PPE PPE Code
208/240 1-ø 0 4 3 6, contact EWC Class 0 gloves with leather protectors and insulated tools Green
120/240, 277/480 3-ø non service entrance 1, 2 6 4, 1 EWC accessories Class 0 gloves with leather protectors and insulated tools Blue
120/240, 277/480 3-ø service entrance 3 Contact FMOC project lead 4, 1 ISC Class 0 gloves with leather protectors and insulated tools Yellow
120/240, 277/480 3-ø service entrance 4 Contact FMOC project lead 4, 1 ESC Class 0 gloves with leather protectors and insulated tools Orange
Equipment labeled greater than 40 calories or 600 volts NA Contact SDR, CO, or PM for assistance Contact SDR, CO, or PM for assistance Red
EWC FR long sleeve shirt (min arc rating 8)
worn over untreated cotton t-shirt with FR pants
(min arc rating 11, safety glasses Accessories
hard hat w/FR rated face shield, hearing
protection, and leather boots or shoes IWC EWC
accessories FR coveralls (min arc rating 25)
and double layer switching hood. ESC 40-calorie
switching suit w/rated hood and gloves, leather
boots and shoes.
Example Arc Flash Labels
Level I (HC-0) Label
Level II (HC-1 and HC-2) Label
Electro-Magnetic Energy
  • Whenever you have electric power, electric and
    magnetic fields will be generated.
  • The electric field is often generated by the
    alternating voltage of the electrical system. The
    higher the voltage, the greater the electric
    field. Taken together, electric and magnetic
    fields are often referred to as electromagnetic
  • The main effect of exposure to EME is heating of
    tissue and organs.
  • There are rooftop antennas at Sandia that emit
    varying levels of EME so contact your ESH
    coordinator before approaching them

Worker Responsibilities
  • Familiarize yourself with procedures and work
    plans- CSSP
  • Be aware of your surroundings
  • Obey all warnings signs and regulations
  • Always use proper PPE (slide 44)
  • Stop work if an unsafe and/or unexpected
    condition arises
  • Consider ALL electrical equipment energized
    unless locked out and verified de-energized

Worker Responsibilities
  • Do NOT perform unjustified energized work
  • Do not wear jewelry when performing energized
  • Report ALL accidents, regardless of severity to
    Safety Officer/Supervisor
  • Immediately report to your supervisor, anyone
    known to be under the influence of drugs or
  • Be aware of secondary hazards- beryllium,
    radiation, noise, etc
  • Be responsible for your own safety!

Planning Your Work
  • Planning is a key element in performing work
    safely and is the first step in the ISMS process.
  • OSHA and 70E require a job briefing be held
    before any electrical work operation begins.
  • All personnel involved in the job shall be
    briefed on the safety concerns, energy source
    controls and precautions regarding their
  • Should work conditions change or unanticipated
    hazards appear, additional briefings should be
  • Planning must be documented!

Planning Your Work continued
  • Consider ALL hazards
  • When changing a ballast, what hazards are
    involved besides electricity and working from
  • Is there an asbestos issue?
  • Is the fixture in an area known to have dangerous
    levels of Beryllium?
  • How about radiation?

Planning Your Work continued
  • The meeting must cover the following questions
  • Do I thoroughly understand the job?
  • Do I thoroughly understand my role in the job?
  • Am I aware of all the hazards I may encounter?
  • Am I knowledgeable of all the safety rules and
    required personal protective equipment that apply
    to the job?

Performing Your Work
  • All circuits must be considered energized until
    LOTOd and verified de-energized
  • Several events at SNL have been the result of
    failure to verify de-energized
  • Performance of the 0 energy verification still
    requires PPE and boundary establishment (slide
  • Do you have to do this hot?
  • Physically establish the limited approach
    boundary (slide 44)
  • Boundary must keep unqualified workers out of
  • Boundary must warn workers of the hazards inside
    the area

Performing Your Work
  • Wear the appropriate PPE
  • Shirt must be buttoned and sleeves rolled down
  • Flash PPE is required when inside the flash
    protection boundary (slide 44)
  • Crossing the restricted approach boundary
    requires gloves and insulated tools (slide 44)
  • Maintain your gloves
  • Are they out of testing date requirements?
  • Use the right tools for the job
  • Is you meter rated for the task?
  • Several events at SNL have occurred due to use of
    an inappropriate meter
  • Do not deviate from job plan.
  • If work outside of scope is required stop and
    re-evaluate with all involved co-workers.

Module 2 Conclusion
  • Severe hazards associated with energized
    electrical work
  • Energized work is now the exception- not the
    norm- Turn it-off!
  • NFPA 70E provides sound guidance for electrical
    safety in the workplace
  • Applying the standard is basic ISMS- identify the
    hazard, control the hazard
  • Remember there are two primary hazards (shock and
    flash) that must be analyzed and controlled

Module 3 TWD Requirements
  • Q What is considered energized work at SNL?
  • A Any activity inside the Limited Approach
    Boundary (LAB)
  • Crossing the LAB for ANY reason must meet the
    70E justification requirements of 110.8.A.1
    (slide 35)
  • ALL energized work requires a technical work
  • Why? This should be your first question when
    asked to work energized.

Contract Specific Safety Plan (CSSP)
  • The CSSP is the required technical work document
    for all energized work at SNL performed by a
    facilities subcontractor
  • The CSSP must incorporate the required energized
    work permit elements required in NFPA 70E 130.1B2

Content of the CSSP
  1. A description of the circuit/part to be worked on
    and its location
  2. Justification of why the work must be performed
    energized. Remember that some troubleshooting
    could be accomplished with an Ohm meter.
  3. A description of safe work practices to be
    employed (second person, safety watch, Barriers,
  4. Results of the shock hazard analysis (voltage the
    employee(s) will be exposed to) slide 44
  5. Determination of shock approach boundaries (LAB,
    RAB, PAB) using table slide 44

Content of the CSSP continued
  • 6. Results of the flash hazard analysis
    (determination of the Flash Protection Boundary
    and the caloric exposure based on table slide 44
  • 7. The necessary personal protective equipment-
    shock and flash
  • Means used to restrict access of unqualified
    personnel to the area (chains, flagging, signage,
  • Evidence of completion of a pre-job briefing
    including topics covered- checklist
  • Energized work approvals (workers, Managers,
    Senior Managers)

Insulated Tools
  • Insulated tools, rated for the system voltage,
    are required when contacting any energized
    component. Insulated tools should be listed under
    3. Ground hooks shall also be listed here.
  • If the insulated tool can prevent the user from
    crossing the restricted approach boundary and
    flash protection boundary, PPE will not be
    required (except safety glasses).

Module 4 Safe Switching Procedures
  • Three hazards associated with switching breakers
    or disconnects
  • Shock
  • Explosion
  • Arc flash/blast

  • Rare when switching because cover should be in
  • Remember shock boundaries
  • 30,000 non-fatal shocks each year in the
  • 247 died from electrocution in 2006down from 251
    in 2005.

Breaker Explosion
  • Counterfeit Products
  • Sub-standard components
  • No NRTL listing
  • Improper Sizing
  • Improperly rated for available fault current

Arc Flash - 2006
Operating Breakers and Disconnects
  • Use one hand when possible.
  • For side-handled switches, stand as far away to
    the side as possible to operate the switch.
  • For panel-mounted breakers, do not stand in front
    of the panel when operating the breaker.
  • Do not expose unprotected portions of the
    body/face to the potential blast.

Review Switching Operations
Disconnect Rating Required PPE (Hazard Category)
Up to and including 60 amps (lt 600 volts) HC 0
gt60 up to and including 200 amps (lt 600 volts) HC 2
gt 200 amps (lt 600 volts) and all gt 600 volts Must be analyzed by a qualified person. Contact electrical safety for evaluation.
  • Arc flash labels supersede this table
  • reference slide 44 for specifics

Module 4 Conclusion
  • Switching can be hazardous
  • Wear appropriate PPE
  • Obtain AIC and clearing times prior to switching
  • Never switch breakers or disconnects under trip
    conditions - call facilities
  • Never close a breaker or disconnect if
  • Use Left hand rule to keep body away from
    disconnect when closing

Course Wrap-Up
  • You seldom get a second chance with electricity
  • Most electrical accidents are caused by unseen or
    unanticipated hazards
  • Take your time!
  • Never deviate from procedures
  • If circumstances or conditions change- STOP and
  • Work on energized equipment is restricted at SNL
  • Maintain tools, test equipment, and PPE
  • Never rely on others for your safety

Thanks for Viewing
Questions Greg Kirsch at 845-9497 Mark McNellis
at 845-4895 Marc Williams at 845-8795
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