Csao Arc Flash Hazards
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Transcript of Csao Arc Flash Hazards
PB/RH July 16, 200811
ARC FLASH HAZARDS
Construction SafetyAssociation of Ontario
22 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Purpose of this Presentation
Introduction to:
– Hazard of arc flash
– New CSA Standard on electrical safety
– Arc flash prevention and protection
33 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Five Main Topics
1. Introduction to arc flash
2. Arc flash injuries
3. Codes and standards
4. Protective clothing and equipment
5. Prevention
PB/RH July 16, 200844
Topic 1 – Topic 1 – Introduction to Arc FlashIntroduction to Arc Flash
4
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What is an Arc Flash Hazard?
“. . . a dangerous condition associated with the release of energy caused by an electric arc.”
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What is an Electric Arc?
An electric arc is a short circuit through the air.
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What is Arc Blast?
1. The flash causes an explosive expansionof 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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Video Clip 1 – Arc Flash DemoVideo Clip 1 – Arc Flash Demo
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Electric arc Arc flash Arc blast
Arc Flash Events
Compliments ofSalisbury Electrical Safety L.L.C.
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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
1111 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
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.
Characteristics of an Electric Arc
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Arc Energy
Noise
Expansion
Vaporization
Thermal radiation
PB/RH July 16, 20081313
Topic 2 – Arc Flash InjuriesTopic 2 – Arc Flash Injuries
13
1414 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Arc Flash Injuries
Electric shock
Severe burns
Blindness
Blast injuries
– Shrapnel wounds
– Lung blast injuries
– Ruptured eardrums
– Pressure wave injuries
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1. Power – amount of energy at the arc
2. Distance – of the worker to the arc
3. Time – duration of the arc exposure
Severity Factors
1616 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Video Clip 2 – “Not Safe at 18 inches”
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Video Clip 3 – “Not Safe Working Near”
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Electric Shock Injury – Burn
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Severe Burns from Arc Flash
Arc flash up to 35,000°F
Sun 9,900°F
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Probability of Surviving Burns
0
20
40
60
80
100
20+ 30+ 40+ 50+
25% Body Burn
50% Body Burn
75% Body Burn
% S
urv
ival
Age Range, Years
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Blindness
Flash of light is so intense it can damage vision.
2222 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Shrapnel Wounds
Material and molten metal can hit the body at over
700 miles per hour.
2323 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Blast Lung Injury (BLI)
Arc blast can cause inhalation injuries.For example:– Inhaling high temperature
copper vapour.– More than 100 toxic
substances can be foundin the fumes.
BLI + Burns = Greater chance of death
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Hearing Damage
Arc blast at 2 feet 145 decibels
Jet engine at 200 feet 132 decibels
Pain threshold 130 decibels
2525 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
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
PB/RH July 16, 20082626
Topic 3 – Topic 3 – Codes and StandardsCodes and Standards
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Standards
US Occupational Safety & Health Administration
US National Fire Protection Association -Standard NFPA 70E
Institute of Electrical & Electronics Engineers -Standard 1584
Canadian Standards Association -Standard Z-462 (in 2009)
Occupational Health & Safety Act -Applicable regulations
Canadian Electrical Code -Rule 2-306
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What is NFPA 70E?
National Fire Protection Association
“Standard for Electrical Safety in the Workplace”
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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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Electrical Safety Program
Arc Flash Hazard Analysis
– Flash Protection Boundary
– Fault Current Calculations
– Arc Fault Clearing Time
– Incident Energy Exposure
Required PPE
CSA Standard Z462 will address:
3131 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Institute of Electrical and Electronics Engineers
A guide for performing arc flash hazard calculations.
What is IEEE Standard 1584?
3232 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
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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Sample label that complies with CEC Rule 2-306.
Required Warning Label
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Optional Warning Label
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Topic 4 – Protective ClothingTopic 4 – Protective Clothingand Equipmentand Equipment
35
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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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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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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.
FR Rated Clothing
Photo compliments ofSalisbury Electrical Safety L.L.C.
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Synthetic Clothing
Synthetic clothing that melts shall not be worn, such as:– Acetate– Nylon– Polyester– Polypropylene– Spandex.
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Video Clip 4 – 100% Cotton Clothing
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Video Clip 5 – Polyester/Cotton Clothing
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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 providearc flash protection:– Face shield
– Gloves, etc.
Photo compliments ofSalisbury Electrical Safety L.L.C.
4343 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Increases level of protection.
May be lighter than a singleheavy garment.
Manufacturer must providethe new combined arc ratingafforded by layering.
FR Clothing Can Be Layered
Photo compliments ofSalisbury Electrical Safety L.L.C.
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Video Clip 6 – FR Clothing
4545 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Tell the supplier that you needarc flash rated PPE and clothing.
PPE must have some resistance to:– Flame– Ignition– Melting.
Obtain PPE from a known and
trusted supplier.
When Purchasing PPE
Not all FR clothing is tested to ASTM F1506
Photo compliments ofSalisbury Electrical Safety L.L.C.
PB/RH July 16, 20084646
Topic 5 – PreventionTopic 5 – Prevention
46
4747 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
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.
4848 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Reduce the fault clearing time.
Reduce the short-circuit current.
Improve equipment maintenance.
Use flash resistant equipment.
CONTROLLING ARC FLASH HAZARDS
At the Source
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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.
CONTROLLING ARC FLASH HAZARDS
Along the Path
5050 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Energized electrical work permit
Barriers
Training and skills
Job briefings
PPE
Tools
CONTROLLING ARC FLASH HAZARDS
At the Worker
Photo compliments ofSalisbury Electrical Safety L.L.C.
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Conduct a Flash Hazard Analysis to determine the
Flash Protection Boundary Incident Energy exposure Type and arc rating of PPE
If work must be done on or near energized electrical equipment,
identify the potential for arc flash.
Arc Flash Hazard Analysis
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Typical Protective Clothing
Hazard/Risk Category Clothing Description Required Minimum
Clothing Arc Rating
0 Non-melting, flammable materialwith fabric weight of at least 4.5 oz/yd
Not applicable
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 orCotton underwear + 2 FR coveralls
25 calories/cm²
4 Cotton underwear + FR shirt + FR pants + multi-layer flash suit
40 calories/cm²
Based on the 2004 edition of NFPA 70E
5353 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
Typical PPE Requirements
Hazard/RiskCategory
Eye Protection
Face & Head Protection
Ear Canal Inserts
Arc-ratedFace Shield
Flash Suit Hood
0 1 2
Double-layerSwitching Hood
3 4
Based on the 2004 edition of NFPA 70E
5454 PB/RH July 16, 2008Arc Flash Hazards -- Construction Safety Association of Ontario
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.
PB/RH July 16, 20085555
ARC FLASH HAZARDSARC FLASH HAZARDS
It is ALWAYS
preferable to work on
de-energized equipment.
55