Transcript Arc Flash Energy and Protection by EWB Engineering

Arc Flash Energy & Protection
Presented by EWB Engineering
(Electrical Engineers)
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
Arc Flash Event
Every Day An
Electrician Is
Severely
Injured by an
Arc Flash Event
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
Recent Changes
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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
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.
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.”
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.
Results of Arc Flash Analysis
• Flash Protection Boundary
• Incident Arc Energy
• Hazard Level for PPE
Arc Flash Principles
 Radiated Energy From Flash
 Radiated Energy Function of
 Arc Power
 Distance From Arc
AC Volts
 Time to Extinguish Arc
 Arc Power Function of
 Arc Voltage & Arc Current
 Arc Voltage Function of
 Arc Gap
Incident Arc Energy
The amount of
energy impressed
on a surface, a
certain distance
from the source,
generated during
an arc event.
Arc Flash Boundary
A distance from
exposed live
parts within
which a person
could receive a
second degree
burn.
Determine PPE Hazard Level
Category
Cal / cm2
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
FR Clothing
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
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
Arc Flash PPE Categories
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Category 0
Untreated Cotton
(Long Sleeve)
Untreated Cotton
Pants (Long)
Voltage Rated Gloves
Safety Glasses
Hard Hat
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Category 1
FR Long Sleeve Shirt
Untreated Cotton Pants
(Long)
FR Pants (Long)
Safety Glasses
Voltage Rated Gloves
Hard Hat
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
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
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
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