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1
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- Construction Safety
Association of Ontario
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2
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- Introduction to:
- Hazard of arc flash
- New CSA Standard on electrical safety
- Arc flash prevention and protection
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3
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- 1. Introduction to arc flash
- 2. Arc flash injuries
- 3. Codes and standards
- 4. Protective clothing and equipment
- 5. Prevention
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4
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5
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- “. . . a dangerous condition associated with the release of energy
caused by an electric arc.”
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6
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- An electric arc is a short circuit through the air.
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7
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- The flash causes an explosive expansion
of air and metal.
- For example: When copper vapourizes it expands by a factor of 67,000.
- The blast produces dangerous:
- Pressure waves
- Sound waves
- Molten steel and shrapnel.
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8
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9
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- Electric arc Arc
flash Arc blast
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10
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- 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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11
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- 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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12
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- Noise
- Expansion
- Vaporization
- Thermal radiation
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13
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14
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- Electric shock
- Severe burns
- Blindness
- Blast injuries
- Shrapnel wounds
- Lung blast injuries
- Ruptured eardrums
- Pressure wave injuries
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15
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- Power – amount of energy at the arc
- Distance – of the worker to the arc
- Time – duration of the arc exposure
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16
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17
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18
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19
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20
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21
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- Flash of light is so intense it can damage vision.
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22
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23
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- Arc blast can cause inhalation injuries.
For example:
- Inhaling high temperature
copper vapour.
- More than 100 toxic
substances can be found
in the fumes.
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24
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25
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- 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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26
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27
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28
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29
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- 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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30
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- 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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31
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- Institute of Electrical and Electronics Engineers
- A guide for performing arc flash hazard calculations.
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32
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- 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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33
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- Sample label that complies with CEC Rule 2-306.
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34
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35
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36
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- 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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37
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- 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.
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38
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- 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.
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39
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- Synthetic clothing that melts shall not be worn, such as:
- Acetate
- Nylon
- Polyester
- Polypropylene
- Spandex.
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40
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41
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42
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- Required minimum clothing:
- Non-melting, flammable material,
- Fabric weight of at least 4.5 oz/yd.
- PPE must also provide
arc flash protection:
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43
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- Increases level
of protection.
- May be lighter
than a single
heavy garment.
- Manufacturer must verify (through testing) the new arc flash rating of
the layering.
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44
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45
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- Tell the supplier that you need
arc flash rated PPE and clothing.
- PPE must have some resistance to:
- Obtain PPE from a known and
- trusted supplier.
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46
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47
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- 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
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48
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- Reduce the fault clearing time.
- Reduce the short-circuit current.
- Improve equipment maintenance.
- Use flash resistant equipment.
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49
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- 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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50
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- Energized electrical work permit
- Barriers
- Training and skills
- Job briefings
- PPE
- Tools
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51
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- Conduct a Flash Hazard Analysis to
- determine the
- Flash Protection Boundary
- Incident Energy exposure
- Type and arc rating of PPE
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52
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53
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54
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- Include Electrical Safety in your Occupational Health and Safety
Management Program.
- Use an electrical work permit system.
- Conduct regular equipment maintenance and label equipment that poses a
flash hazard.
- Confirm single-line diagrams for accuracy and available fault current.
- Maintain documentation process.
- Provide training and job briefings.
- Conduct periodic safety audits.
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55
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- It is ALWAYS
preferable to work on
de-energized equipment.
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Notes
