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ARC FLASH HAZARDS by iyf57920

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									     ARC FLASH HAZARDS


             Construction Safety
             Association of Ontario



11                        PB/RH July 16, 2008
    Purpose of this Presentation

       Introduction to:
        – Hazard of arc flash
        – New CSA Standard on electrical safety
        – Arc flash prevention and protection




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2   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
    Five Main Topics

    1. Introduction to arc flash
    2. Arc flash injuries
    3. Codes and standards
    4. Protective clothing and equipment
    5. Prevention
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3   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
             Topic 1 –
     Introduction to Arc Flash




44                        PB/RH July 16, 2008
    What is an Arc Flash Hazard?
    “. . . a dangerous condition associated with the
       release of energy caused by an electric arc.”




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5   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
    What is an Electric Arc?

       An electric arc is a short circuit through the air.




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6   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
    What is Arc Blast?

    1. The flash causes an explosive expansion
       of air and metal.
              – For example: When copper vapourizes it
                expands by a factor of 67,000.


    2. The blast produces dangerous:
              – Pressure waves
              – Sound waves
              – Molten steel and shrapnel.

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7   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
    Video Clip 1 – Arc Flash Demo




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8   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
    Arc Flash Events

    Electric arc                            Arc flash                      Arc blast




                                                                              Compliments of
                                                                      Salisbury Electrical Safety L.L.C.

9
9   Arc Flash Hazards -- Construction Safety Association of Ontario         PB/RH July 16, 2008
     What Causes Arc Flash?

        Dust, impurities, corrosion, condensation, animals

        Spark discharge from:
         – Accidental touching

         – Dropping tools

        Over-voltages across narrow gaps

        Failure of insulating materials

        Equipment failure


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10   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Characteristics of an Electric Arc

        An electric arc will oscillate and escalate if
         not constrained.
        A single-phase electric arc can engulf a
         second or third conductor in only two cycles.
        An electric arc‟s current propels the arc away
         from the power source.



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11   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Arc Energy

        Noise

        Expansion

        Vaporization

        Thermal radiation


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12   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Topic 2 – Arc Flash Injuries




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13                         PB/RH July 16, 2008
     Arc Flash Injuries

                                                      Electric shock
                                                      Severe burns
                                                      Blindness
                                                      Blast injuries
                                                          – Shrapnel wounds
                                                          – Lung blast injuries
                                                          – Ruptured eardrums
                                                          – Pressure wave injuries
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14   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Severity Factors

                                                      1. Power – amount
                                                              of energy at the arc

                                                      2. Distance – of the
                                                              worker to the arc

                                                      3. Time – duration of
                                                              the arc exposure

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15   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Video Clip 2 – “Not Safe at 18 inches”




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16    Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
Video Clip 3 – “Not Safe Working Near”




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17   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Electric Shock Injury – Burn




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18   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Severe Burns from Arc Flash




     Arc flash               up to 35,000°F
     Sun                                   9,900°F
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19   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Probability of Surviving Burns
                  100


                  80
     % Survival




                  60
                                                                          25% Body Burn
                                                                          50% Body Burn
                  40
                                                                          75% Body Burn

                  20


                   0
                        20+         30+            40+           50+
                                Age Range, Years
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20    Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Blindness

        Flash of light is so intense it can
         damage vision.




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21   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Shrapnel Wounds




                                             Material and molten metal
                                              can hit the body at over
                                                700 miles per hour.
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22   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Blast Lung Injury (BLI)

     Arc blast can cause inhalation injuries.
      For example:
         – Inhaling high temperature
           copper vapour.
         – More than 100 toxic
           substances can be found
           in the fumes.

            BLI + Burns = Greater chance of death

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23   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Hearing Damage



                  Arc blast at 2 feet                                  145 decibels

                  Jet engine at 200 feet                               132 decibels

                  Pain threshold                                       130 decibels


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24   Arc Flash Hazards -- Construction Safety Association of Ontario      PB/RH July 16, 2008
     Pressure Wave Injuries

     Arc blast can throw a worker:
         – Off a ladder
         – Into nearby walls or equipment.
      2000 lbs/ft2 pressure on the body can cause:
         – Concussion
         – Collapsed lungs
         – Other internal injuries


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25   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
          Topic 3 –
     Codes and Standards




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26                    PB/RH July 16, 2008
     Standards                               US National Fire Protection Association
                                             -Standard NFPA 70E

      Canadian Standards Association
      -Standard Z-462
       (in 2009)
                                                                 Institute of Electrical &
                                                                 Electronics Engineers
        Canadian Electrical Code                                  -Standard 1584
        -Rule 2-306


                                                    Occupational Health & Safety Act
      US Occupational Safety &                      -Applicable regulations
      Health Administration



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27   Arc Flash Hazards -- Construction Safety Association of Ontario        PB/RH July 16, 2008
     What is NFPA 70E?

             National Fire Protection Association




     “Standard for Electrical Safety in the Workplace”

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28   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     What is CSA Standard Z462?

                Canadian Standards Association



          Standard for electrical safety in Canadian workplaces.

          Will be “harmonized” with NFPA 70E.
          To be completed in 2009.


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29   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     CSA Standard Z462 will address:

          Electrical Safety Program
          Arc Flash Hazard Analysis
         – Flash Protection Boundary
         – Fault Current Calculations
         – Arc Fault Clearing Time
         – Incident Energy Exposure
          Required PPE
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30   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     What is IEEE Standard 1584?

      Institute of Electrical and Electronics
                      Engineers




     A guide for performing arc flash hazard
      calculations.

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31   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     What is CEC Rule 2-306?

                        Canadian Electrical Code




      “Rule 2-306 Shock and Flash Protection”
         A requirement for field-marking electrical
          equipment to warn persons of potential
          electric shock and arc flash hazards.

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32   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Required Warning Label




        Sample label that complies with CEC Rule 2-306.

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33   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Optional Warning Label




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34   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Topic 4 – Protective Clothing
            and Equipment




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35                          PB/RH July 16, 2008
     Flame-Resistant (FR) Clothing

        Protects a worker from receiving severe
         burns if the worker is exposed to a flame.
        Is self-extinguishing when the source of the
         flame is removed.
        Must be worn to limit the „Incident Energy‟
         level of the arc flash to 1.2 cal/cm² against
         the worker‟s chest.


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36   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     What is a Calorie?

      A calorie is the amount of heat needed to raise
       the temperature of one gram of water by 1°C.
      Thermal energy is measured in calories/cm².

         1.2 calories/cm² = Holding your finger
                            in the blue part of the
                            flame for one second.




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37   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     FR Rated Clothing

        Look for a label that states:
         – 1506 approval (ASTM F1506)
         – Arc rating of the garment.
        All materials in the garment
         should be FR Rated:
         – Thread
         – Buttons
         – Insulation
         – Zippers, etc.

                                                                       Photo compliments of
                                                                  Salisbury Electrical Safety L.L.C.
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38   Arc Flash Hazards -- Construction Safety Association of Ontario              PB/RH July 16, 2008
     Synthetic Clothing

        Synthetic clothing that melts shall not
         be worn, such as:
         – Acetate
         – Nylon
         – Polyester
         – Polypropylene
         – Spandex.


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39   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Video Clip 4 – 100% Cotton Clothing




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40   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
Video Clip 5 – Polyester/Cotton Clothing




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41   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Arc Flash Rated PPE

      Required minimum clothing:
         – Non-melting, untreated, natural fibre with a
           fabric weight of at least 4.5 oz/yd.
      PPE must also provide
       arc flash protection:
         – Face shield
         – Gloves, etc.


                                                                            Photo compliments of
                                                                       Salisbury Electrical Safety L.L.C.

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42   Arc Flash Hazards -- Construction Safety Association of Ontario            PB/RH July 16, 2008
     FR Clothing Can Be Layered

        Increases level of protection.

        May be lighter than a single
         heavy garment.

        Manufacturer must provide
         the new combined arc rating
         afforded by layering.                                  Photo compliments of
                                                           Salisbury Electrical Safety L.L.C.

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43   Arc Flash Hazards -- Construction Safety Association of Ontario               PB/RH July 16, 2008
                            Video Clip 6 – FR Clothing




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44   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     When Purchasing PPE

      Tell the supplier that you need
       arc flash rated PPE and clothing.
      PPE must have some resistance to:
        – Flame
        – Ignition
        – Melting.
      Obtain PPE from a known and
                                                Photo compliments of
       trusted supplier.                   Salisbury Electrical Safety L.L.C.


       Not all FR clothing is tested to ASTM F1506
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45   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     Topic 5 – Prevention




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46                     PB/RH July 16, 2008
     Tasks with Potential for Arc Flash

        Operating a switch or circuit breaker
        Inserting or removing a circuit breaker
        Opening an enclosure door
        Removing a cover (bolted or hinged)
        Testing for voltage

     In each task:
         Worker is interacting with energized equipment.

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47   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     CONTROLLING ARC FLASH HAZARDS
                               At the Source

        Reduce the fault clearing time.

        Reduce the short-circuit current.

        Improve equipment maintenance.

        Use flash resistant equipment.



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48   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     CONTROLLING ARC FLASH HAZARDS
                             Along the Path

        Increase the working distance.
        Reduce the energy exposure.
        Use hinged doors instead of bolted
         doors to eliminate the risk of bolts
         falling into the panel.
        Work de-energized.

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49   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     CONTROLLING ARC FLASH HAZARDS
                               At the Worker

        Energized electrical work permit
        Barriers
        Training and skills
        Job briefings
        PPE
        Tools
                                                                 Photo compliments of
                                                            Salisbury Electrical Safety L.L.C.

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50   Arc Flash Hazards -- Construction Safety Association of Ontario                PB/RH July 16, 2008
     Arc Flash Hazard Analysis

               If work must be done on or near
                energized electrical equipment,
              identify the potential for arc flash.

      Conduct a Flash Hazard Analysis to
           determine the
                   Flash Protection Boundary
                   Incident Energy exposure
                   Type and arc rating of PPE

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51   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
                                       Based on the 2004 edition of NFPA 70E

     Typical Protective Clothing

     Hazard/Risk                                                       Required Minimum
      Category
                               Clothing Description                    Clothing Arc Rating

           0          Non-melting, flammable material                     Not applicable
                      with fabric weight of at least 4.5 oz/yd
           1          FR shirt + FR pants or FR coveralls                 4 calories/cm²

           2          Cotton underwear + FR shirt + FR pants              8 calories/cm²

           3          Cotton underwear + FR shirt/pants/coveralls or     25 calories/cm²
                      Cotton underwear + 2 FR coveralls

           4          Cotton underwear + FR shirt + FR pants +           40 calories/cm²
                             multi-layer flash suit

52
52   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
                                       Based on the 2004 edition of NFPA 70E

     Typical PPE Requirements
     Hazard/Risk  Eye                Face & Head        Ear Canal       Arc-rated    Flash Suit
      Category Protection             Protection         Inserts       Face Shield     Hood

          0              
          1              
          2                                                            
                                      Double-layer
                                     Switching Hood

          3                                                                          
          4                                                                          
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53   Arc Flash Hazards -- Construction Safety Association of Ontario         PB/RH July 16, 2008
     Prevention Summary
     1.    Include Electrical Safety in your Occupational
           Health and Safety Management Program.
     2.    Use an electrical work permit system.
     3.    Conduct regular equipment maintenance and label
           equipment that poses a flash hazard.
     4.    Confirm single-line diagrams for accuracy and
           available fault current.
     5.    Maintain documentation process.
     6.    Provide training and job briefings.
     7.    Conduct periodic safety audits.
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54   Arc Flash Hazards -- Construction Safety Association of Ontario   PB/RH July 16, 2008
     ARC FLASH HAZARDS

                  It is ALWAYS
              preferable to work on
             de-energized equipment.




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55                        PB/RH July 16, 2008

								
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