Transcript Arc Flash Hazards presentation - Welcome to Infrastructure

ARC FLASH HAZARDS
Construction Safety
Association of Ontario
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PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Topic 1 –
Introduction to Arc Flash
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PB/RH -- March 3, 2009
What is an Arc Flash Hazard?
“. . . a dangerous condition associated with the
release of energy caused by an electric arc.”
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What is an Electric Arc?

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An electric arc is a short circuit through the air.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Characteristics of an Electric Arc
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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.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What Causes Arc Flash?

Dust, impurities, corrosion, condensation, animals

Spark discharge from:
– Accidental touching
– Dropping tools
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
Over-voltages across narrow gaps

Failure of insulating materials

Equipment failure
Arc Flash Hazards -- Construction Safety Association of Ontario
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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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Video Clip 1 – Arc Flash Demo
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Arc Flash Events
Electric arc
Arc flash
Arc blast
Compliments of Salisbury Electrical
Safety L.L.C.
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Forms of Arc Flash Energy
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
Noise

Expansion

Vaporization

Thermal radiation
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Topic 2 – Arc Flash Injuries
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Arc Flash Injuries
 Electric shock
 Severe burns
 Blindness
 Blast injuries
– Shrapnel wounds
– Lung blast injuries
– Ruptured eardrums
– Pressure wave injuries
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Video Clip 2 – “Not Safe at 18 inches”
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Video Clip 3 – “Not Safe Working Near”
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Electric Shock Injury – Burn
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Severe Burns from Arc Flash
Arc flash
Sun
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up to 35,000°F
9,900°F
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Probability of Surviving Burns
100
% Survival
80
60
25% Body Burn
50% Body Burn
75% Body Burn
40
20
0
20+
30+
40+
50+
Age Range, Years
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Blindness

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Flash of light is so intense it can
damage vision.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Shrapnel Wounds
Material and molten metal
can hit the body at over
700 miles per hour.
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Hearing Damage
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Arc blast at 2 feet
145 decibels
Jet engine at 200 feet
132 decibels
Pain threshold
130 decibels
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Topic 3 –
Codes and Standards
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Standards
US National Fire Protection Association
-Standard NFPA 70E
Canadian Standards Association
-Standard Z-462
Canadian Electrical Code
-Rule 2-306
US Occupational Safety &
Health Administration
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Institute of Electrical &
Electronics Engineers
-Standard 1584
Occupational Health & Safety Act
-Applicable regulations
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What is NFPA 70E?
National Fire Protection Association
“Standard for Electrical Safety in the Workplace”
• Standard for electrical safety in United Sates
• “Harmonized” with CSA Z462
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What is CSA Standard Z462?
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
The standard for workplace electrical
safety in Canada.

“Harmonized” with NFPA 70E.
Arc Flash Hazards -- Construction Safety Association of Ontario
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CSA Standard Z462 addresses:

Electrical Safety Program

Arc Flash Hazard Analysis
– Flash Protection Boundary
– Fault Current Calculations
– Arc Fault Clearing Time
– Incident Energy Exposure

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Required PPE
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What is IEEE Standard 1584?
Institute of Electrical and Electronics
Engineers
Offers a method for performing arc
flash hazard calculations.
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
What is CEC Rule 2-306?
Canadian Electrical Code
“Rule 2-306 Shock and Flash Protection”

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A requirement for field-marking electrical
equipment to warn persons of potential
electric shock and arc flash hazards.
Arc Flash Hazards -- Construction Safety Association of Ontario
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Required Warning Label

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Sample label that complies with CEC Rule 2-306.
Arc Flash Hazards -- Construction Safety Association of Ontario
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Optional Warning Label
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Topic 4 – Protective Clothing
and Equipment
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Flame-Resistant (FR) Clothing
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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.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
FR Rated Clothing

Limit the ‘Incident Energy’ level of the
arc flash to 1.2 cal/cm² against the
worker’s chest.

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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Typical PPE Requirements
Hazard/Risk Eye protection, ear canal
Category
inserts, long sleeve shirt
and pants
0
1
2
3
4
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Arc rated
clothing
Face & Head
Protection
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Arc Flash Hazards -- Construction Safety Association of Ontario
Flash Suit
Hood
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Typical Protective Clothing
Hazard/Risk
Category
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Clothing Description
Required Minimum
Clothing Arc Rating
0
Non-melting, flammable material
with fabric weight of at least 4.5 oz/yd2
Not applicable
1
2
3
Arc-rated FR shirt + FR pants or FR coveralls
4 calories/cm²
Arc-rated FR shirt + FR pants or FR coveralls
8 calories/cm²
Arc-rated FR shirt + FR pants or FR coveralls,
and Arc-rated flash suit, the layered system
must meet the required minimum rating.
25 calories/cm²
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Arc-rated FR shirt + FR pants or FR coveralls,
and Arc-rated flash suit, the layered system
must meet the required minimum rating.
40 calories/cm²
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Synthetic Clothing

Synthetic clothing that melts shall not
be worn, such as:
– Acetate
– Nylon
– Polyester
– Polypropylene
– Spandex.
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Arc Flash Rated PPE
 Required minimum clothing:
– Non-melting, flammable material,
– 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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Video Clip 4 – 100% Cotton Clothing
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Video Clip 5 – Polyester/Cotton Clothing
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Arc Flash Hazards -- Construction Safety Association of Ontario
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Video Clip 6 – FR Clothing
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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
Salisbury Electrical Safety L.L.C.
trusted supplier.
Not all FR clothing is tested to ASTM F1506
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Topic 5 – Prevention
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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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Arc Flash Hazards -- Construction Safety Association of Ontario
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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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
CONTROLLING ARC FLASH HAZARDS
At the Source
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
Reduce the fault clearing time.

Reduce the short-circuit current.

Improve equipment maintenance.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
CONTROLLING ARC FLASH HAZARDS
At the Source

Use flash-resistant equipment.
These disconnect switch-plugs have been
designed with built-in flash-protection.
Photos courtesy of Meltric Corporation
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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
CONTROLLING ARC FLASH HAZARDS
Along the Path
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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.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
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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Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
Prevention Summary
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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.
Arc Flash Hazards -- Construction Safety Association of Ontario
PB/RH -- March 3, 2009
ARC FLASH HAZARDS
It is ALWAYS
preferable to work on
de-energized equipment.
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