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Arc Flash Energy Protection by EWB Engineering
1. Arc Flash Energy & Protection
Presented by EWB Engineering
(Electrical Engineers)
2. 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
4. 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
5. 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
6. 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.
7. 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.”
8. 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.
9.
10. Results of Arc Flash Analysis
• Flash Protection Boundary
• Incident Arc Energy
• Hazard Level for PPE
11. 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
12. Incident Arc Energy
The amount of
energy impressed
on a surface, a
certain distance
from the source,
generated during
an arc event.
13. Arc Flash Boundary
A distance from
exposed live
parts within
which a person
could receive a
second degree
burn.
15. 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
16. 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
17. Arc Flash PPE Categories
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•
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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
19. 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
20. Arc Flash PPE Categories
Category 4
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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
21. 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
