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Arc Flash & Arc Blast
• Arc Flash – electrical short circuit
that occurs when air flashes from
an exposed live conductor, to
either another conductor or to
ground.
• Arc Blast – pressure wave caused
by the arc flash
Arc Flash/Blast
• Concentrated energy explodes
outward
• High intensity flash
• Temperatures can reach 35,000
(skin ignites 480)
• Pressure wave can reach
200lbs/sq. inch
• Vaporizes conductors and
copper with exploding particles.
Arc Flash Effects
• Severe burns
• Broken bones
• Vision damage
• Hearing loss
• Brain/internal injuries
• Punctures and lacerations
• Death
SCOPE OF THE PROBLEM
• Each year, MSHA identifies about 100 injuries as “non-contact electric arc burns”
• 55% are in bituminous coal
• 84% are on systems of 600V or less
MSHA DATA
Causes of Arc Flash
• Improper training
• Improper work procedures
• Dropped tools
• Accidental contact with electrical
systems
• Installation failure
• Improper Design/Repair
• Voltage testing with inappropriate
equipment
Causes of Arc Flash (cont.)
• Buildup of dust, corrosion
on insulating surfaces
• Lack of maintenance
• Sparks produced during
racking of breakers,
replacement of fuses and
closing into faulty lines.
• Over confidence
MSHA 75 and 77
All power circuits and electrical equipment shall be deenergized before work is done on such circuits and equipment, except when necessary for trouble shooting or testing.
Trouble shooting and Testing
• Only low and medium voltage circuits
• Purpose is to determine voltage and current
• Qualified person with protective gloves
ARC FLASH PREVENTION
The best way to prevent arc flash incidents is to DE-ENERGIZE and LOCK/TAG circuits before beginning work.
If we are Locking out properly, then when do we have exposure/risk?
• Trouble shooting and testing
• Removing covers, doors and lids with energized parts.
• Inadequate Barriers between circuits.
Energized Work Approval
• Description of the task to be performed• Justification for energized work• Job specific hazards• PPE
Can be verbal or written (AMS Operator) Adds accountability/ Helps define SAFE
Low/Medium rated Gloves
• Can use dry Leather work gloves in Good Condition
• Over 120 volts systems must be intrinsically safe
IEEE Standard 1584
Systems rated below 240 V to ground and below about 400A (125kVA) are not considered ARC FLASH Hazards.
These systems still present a SHOCK Hazard.
Arc-Rated FR Clothing & PPE
• Layering
– Outer layers must be flame resistant
– Under layers must be non-melting
• Coverage – Clothing must cover potentially exposed areas (wrist, neck)
• Care & Maintenance
– Inspect before use
– Launder according to mfg’s instructions
PPE - Hazard Risk Category 00-1.2 cal/cm2
• 100% cotton long sleeve shirt• Long pants• Safety glasses• Hearing protection• Leather and insulated gloves (as
required)• Leather work boots
PPE - Hazard Risk Category 11.2 - 4 cal/cm2
• 4+ cal long sleeve shirt & long pants (or) coveralls
• Hardhat• Safety glasses• Arc rated faceshield• Hearing protection (inserts)• VR gloves• Leather gloves• Leather work boots
PPE - Hazard Risk Category 24 - 8 cal/cm2
• 8+ cal long sleeve shirt & long pants (or) coveralls
• Hardhat
• Safety glasses
• Arc rated faceshield
• Hearing protection (inserts)
• VR gloves
• Leather work boots
PPE - Hazard Risk Category 38 - 25 cal/cm2
• 25+ flashsuit w/ hood over long sleeve shirt and long pants
• Safety glasses• Arc rated faceshield• Hearing protection (inserts)• VR gloves• Leather gloves• Leather work boots
PPE - Hazard Risk Category 425 - 40 cal/cm2
• 40+ flashsuit w/ hood over FR long sleeve shirt and long pants
• Safety glasses
• Arc rated faceshield
• Hearing protection (inserts)
• VR gloves
• Leather gloves
• Leather work boots
Summary
• Lock and Tag Program
• Identify activities with exposure
• Determine potential of injury
• Look for alternative methods
• Put administrative controls in place
• Train and provide appropriate PPE
• Evaluate the effectiveness of your process
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from SafetyShare.org41
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