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Electrical Safety
ARC FLASH
ANALYSIS
ARC
Electrical Safety
FLASH ANALYSIS
ARC-FLASH
Electrical Safety
• As much as 80% of all electrical injuries are
burns resulting from an arc-flash and ignition
of flammable clothing.
• Arc temperature can reach 35,000°F - this is
four times hotter than the surface of the sun
Fatal burns can occur at distances over 10 ft.
ARC EXPOSURE ENERGY BASICS
Electrical Safety
• Exposure Energy is Expressed in cal/cm2
• 1 cal/cm2 Equals the Exposure on the tip of a finger
by a Cigarette Lighter in One Second
• An Exposure Energy of Only One or Two cal/cm2
Will Cause a 2nd Degree Burn on Human Skin
Industry Standards and Regulations
Electrical Safety
• OSHA 29 CFR 1910 Subpart S
• OSHA Enforces NEC2002 110.16 & NFPA70E
• NFPA 70E-2000
• Requirements for shock and arc flash boundaries
• Requirements for personal protective equipment
• NEC 110.16-2002
NEC 2002
110.16 Flash Safety
Protection.
Electrical
Switchboards, panel boards, industrial control
panels, and motor control centers in other than dwelling occupancies,
that are likely to require examination, adjustment, servicing, or
maintenance while energized, shall be field marked to warn qualified
persons of potential electric arc flash hazards. The marking shall be
located so as to be clearly visible to qualified persons before
examination, adjustment, servicing, or maintenance of the equipment.
FPN No. 1: NFPA 70E-2000, Electrical Safety Requirements for Employee
Workplaces, provides assistance in determining severity of potential
exposure, planning safe work practices, and selecting personal
protective equipment.
FPN No. 2: ANSI Z535.4-1998, Product Safety Signs and Labels,
provides guidelines for the design of safety signs and labels for
application to products.
Sample NEC Warning Article 110.16
Electrical Safety
WARNING
!
Arc Flash and Shock Hazard
Appropriate PPE Required
ARC Flash Analysis
Electrical Safety
• OSHA 1910.132(d) Where work will be performed within the
flash protection boundary, the flash hazard analysis shall
determine, and the employer shall document, the incident energy
exposure to the worker (in cal/cm2)
• OSHA 1910.269(I)(6) Flame resistant (FR) clothing and PPE
shall be used by the employee based upon the incident energy
exposure associated with the specific task.
• As an alternative, PPE requirements of NFPA 70E Part II 3-3.9
may be used in lieu of a detailed flash hazard analysis.
Sample NEC Warning Article 110.16
Electrical Safety
Electrical Safety
Approach Boundaries
Electrical Safety
Nominal System
Voltage Range
Limited Approach Boundary
Restricted Approach
Boundary
Prohibited Approach
Boundary
Phase-to-Phase
Exposed Moveable
Conductor
Exposed Fixed Circuit
Part
Includes Inadvertent
Movement Adder
0 - 50
Not specified
Not specified
Not specified
Not specified
51 - 300
10 ft. 0 in.
3 ft.6 in.
Avoid contact
Avoid contact
301 - 750
10 ft. 0 in.
3 ft.6 in.
1 ft. 0 in.
0 ft. 1 in.
751V - 15 kV
10 ft. 0 in.
5 ft.0 in.
2 ft. 2 in.
0 ft. 7 in.
15.1 – 36 kV
10 ft. 0 in.
6 ft.0 in.
2 ft. 7 in.
0 ft. 10 in.
36.1 – 46 kV
10 ft. 0 in.
8 ft.0 in.
2 ft. 10 in.
1 ft. 5 in.
46.1 – 72.5 kV
10 ft. 0 in.
8 ft.0 in.
3 ft. 3 in.
2 ft. 1 in.
72.6 – 121 kV
10 ft. 8 in.
8 ft.0 in.
3 ft. 3 in.
2 ft. 8 in.
138 – 145 kV
11 ft. 0 in.
10 ft.0 in.
3 ft. 7 in.
3 ft. 1 in.
NFPA 70E provides two choices for PPE
selection:
Electrical Safety
• Do an arc flash hazard analysis, and document
the incident energy exposure
– IEEE 1584
– SKM (Arc Flash Evaluation Module)
– ArcPro Software
– Duke Power Cal/Flux Software
• As an alternate, use the “Hazard Risk Category
Classifications” table to choose the PPE level
required for the task
Hazard Risk Category Tables
Electrical Safety
Hazard Risk Category Classification
Electrical Safety
• NFPA 70E – Hazard Risk 0
– This hazard risk category poses minimal risk.
• NFPA 70E – Hazard Risk 1
– This hazard risk category poses some risk.
• NFPA 70E – Hazard Risk 2
– This hazard risk category involves tasks that pose a
moderate risk.
• NFPA 70E – Hazard Risk 3
– This hazard risk category involves tasks that pose a
high risk.
• NFPA 70E – Hazard Risk 4
– This hazard risk category represents tasks that pose
the greatest risk.
Methods of Reducing Hazard Risk
Electrical Safety
• Specifying Current Limiting Fuses on Low Voltage
Switchgear Breakers
• Specifying ARC Resistance Medium Voltage
Switchgear
• Remote Control of Switchgear Breakers
• High Resistance Grounding on Low Voltage and
Medium Voltage (15kV and below) Systems
What We Offer Our Clients
Electrical Safety
• Design of safer power systems while insuring
compliance with OSHA NFPA 70E standards and IEEE
1584
• Save time with the fully integrated Short Circuit, Time
Current Coordination, Equipment Evaluation and Arc
Flash Evaluation
• Offer alternatives to reduce exposure to ARC Flash
Energy.