Arc Flash Energy

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Arc Flash Energy Protection

• Presented by EWB Engineering
• (Electrical Engineers)

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Objective

• To Understand
• What is An Arc Flash
• Why OSHA Is Addressing This Issue
• New Requirements In NEC NFPA 70E
• Impact to Industry
• Steps in Performing an Arc Flash Analysis
• How to Select Required Protective Clothing

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Arc Flash Event
Every Day An Electrician Is Severely Injured by
an Arc Flash Event
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What Is An Arc Flash
An Arc Flash is a Sudden Release of Heat and
Energy Caused By An Electric Arc
Arc Resistant Switchgear Undergoing Test For an
Arcing Fault
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Recent Changes

• Attention to Personnel Protection (PPE)
• Recognition of Unsafe Work Practices
• Impact to Business and Medical Costs
• Changes to NFPA 70E NEC
• IEEE Standard for Arc Flash Analysis
• Requirements of OSHA 1910, Subpart S

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What Does OSHA Say?

• 29 CFR 1910.333
• Live electrical parts that an employee may be
  exposed shall be de-energized unless additional
  or greater hazards are introduced.
• 29 CFR 1910.335
• Employees working in areas where potential
  electrical hazards exist shall be provided with
  and shall use personal protective equipment.

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What Does NFPA 70E Say?

• NFPA 70E, Part II, 2-1.3.3
• A flash hazard analysis shall be done before a
  person approaches any exposed electrical
  conductor or circuit part that has not been
  placed in an electrically safe work condition.

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What Does National Electric Code (NEC) Say?

• NEC 110.16
• States Equipment must be marked to warn qualified
  persons of potential electrical arc flash hazards.

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(No Transcript)
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Results of Arc Flash Analysis

• Flash Protection Boundary
• Incident Arc Energy
• Hazard Level for PPE

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Arc Flash Principles

• Radiated Energy From Flash
• Radiated Energy Function of
• Arc Power
• Distance From Arc
• Time to Extinguish Arc
• Arc Power Function of
• Arc Voltage Arc Current
• Arc Voltage Function of
• Arc Gap

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Incident Arc Energy
The amount of energy impressed on a surface, a
certain distance from the source, generated
during an arc event.
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Arc Flash Boundary


A distance from exposed live parts within which a
person could receive a second degree burn.
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Determine PPE Hazard Level

• Category Cal / cm2 FR Clothing
• 0 1.2 Untreated Cotton
• 1 5 FR Shirt FR Pants
• 2 8 Cotton Underwear FR Shirt FR
  Pants
• 3 25 Cotton Underwear FR Shirt FR
  Pants FR Coverall
• 4 40 Cotton Underwear FR Shirt FR
  Pants
• Double Layer Switching Coat Pants

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Calculation Methods

• IEEE 1584
• IEEE Method Preferred
• NFPA 70E Tables
• Can Be Used if Calculations Not Available
• Limited Range of Fault Currents and Protective
  Device Characteristics

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PPE Clothing Requirements

• Employees Required to Wear Flame Resistant (FR)
  Clothing PPE
• The Required Level of Clothing and Personal
  Protection Depends on the
• Calculated Incident Arc Energy
• For
• The Specific Task

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Arc Flash PPE Categories

• Category 0
• Untreated Cotton (Long Sleeve)
• Untreated Cotton Pants (Long)
• Voltage Rated Gloves
• Safety Glasses
• Hard Hat

• Category 1
• FR Long Sleeve Shirt
• Untreated Cotton Pants (Long)
• FR Pants (Long)
• Safety Glasses
• Voltage Rated Gloves
• Hard Hat

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Arc Flash PPE Categories

• Category 2
• Untreated Cotton T-Shirt
• Untreated Cotton Shirt (Long Sleeve)
• FR Shirt (Long Sleeve)
• Untreated Cotton Pants (Long)
• FR Pants (Long)
• Safety Glasses
• Voltage Rated Gloves
• Hard Hat
• Double Layer Bee Keepers Hood

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Arc Flash PPE Categories

• Category 3
• Untreated Cotton T-Shirt
• Untreated Cotton Shirt (Long Sleeve)
• FR Shirt (Long Sleeve)
• Untreated Cotton Pants (Long)
• FR Pants (Long)
• Voltage Rated Gloves
• Safety Glasses
• FR Hard Hat Liner
• Hard Hat
• Double Layer Bee Keepers Hood
• Hearing Protection

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Arc Flash PPE Categories

• Category 4
• Untreated Cotton T-Shirt
• Untreated Cotton Shirt (Long Sleeve)
• FR Shirt (Long Sleeve)
• Untreated Cotton Pants (Long)
• FR Pants (Long)
• FR Coveralls
• Voltage Rated Gloves
• Safety Glasses
• FR Hard Hat Liner
• Hard Hat
• Double Layer Bee Keepers Hood
• Hearing Protection

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Conclusions

• OSHA NFPA 70E Require An Arc Flash Hazard
  Analysis For Proper PPE
• New Requirement in NEC States That Arc Flash
  Warning Labels Be Placed on Electrical Panels and
  Switchboards.
• IEEE 1584 is Preferred Method for Determining Arc
  Flash Incident Energy Arc Flash Boundaries.
• Fault Study
• Coordination Study
• Determine Incident Arc Energy