Electrical Safety

ARC FLASH ANALYSIS

Electrical SafetyARC FLASH ANALYSIS

Electrical Safety

ARC-FLASH

• 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.

Electrical Safety

ARC EXPOSURE ENERGY BASICS

• 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

Electrical Safety

Industry Standards and Regulations

• 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

Electrical SafetyNEC 2002110.16 Flash Protection. 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.

Electrical Safety

Sample NEC Warning Article 110.16

!

WARNING

Arc Flash and Shock HazardAppropriate PPE Required

Electrical SafetyARC Flash Analysis• 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.

Electrical Safety

Sample NEC Warning Article 110.16

Electrical Safety

Electrical SafetyApproach Boundaries

Nominal SystemVoltage Range

Limited Approach Boundary Restricted ApproachBoundary

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.

Electrical Safety

NFPA 70E provides two choices for PPE selection:

• 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

Electrical SafetyHazard Risk Category Tables

Electrical Safety

Hazard Risk Category Classification

• 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.

Electrical Safety

Methods of Reducing Hazard Risk

• 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

Electrical Safety

What We Offer Our Clients

• 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.