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Arc Flash Hazard Calculation Studies – Part 2
May 7, 2015 @ 8:00 am - 5:00 pm
In Part 2 of the 2 day class, Jim Phillips, P.E. shows you how to perform arc flash calculations and conduct the comprehensive arc flash study. You will perform IEEE 1584 calculations of incident energy, arcing current, arc flash boundary and DC arc flash using Jim’s calculation worksheets. You will see how to simplify the arc flash study and arc flash labeling as well as understand how to properly model the power system. Receive answers to questions such as: what if a protective device’s clearing time is too long, what is the “X Distance Factor”, does the type of equipment matter in the calculations? what if the utility information is unavailable, what really needs to go on an arc flash label and much more. Plus, you will also get a peek into the next edition of IEEE 1584.
Jim Phillips is not just another trainer reading a script. Jim’s training is based on his insider’s view from holding many leadership positions for the development of various electrical safety standards coupled with his arc flash testing experience and broad electrical power background. This provides him a unique perspective from the inside – a perspective he loves sharing with others. When asked questions about some topics, his explanations often run along the line of “Well, here’s what happened in the lab when we blew it up…”
Here is a sample of Jim’s involvement.
♦ Vice Chair – IEEE 1584 – IEEE Guide for Performing Arc Flash Calculations
♦ International Chair – Geneva, Switzerland based, IEC TC78 Live Working – 40+ global standards including many for arc flash.
♦ IEEE/NFPA Arc Flash Collaborative Research Project – Member of the Steering Committee
♦ Author of Complete Guide to Performing Arc Flash Hazard Calculation Studies
For a summary of the 2018 changes to NFPA 70E based on Jim’s article published in the multi-award winning Electrical Contractor Magazine, [CLICK HERE]
[Learn more about Jim Phillips]
What You WILL Receive:
♦ Instructions on how to perform an Arc Flash Study
♦ Jim’s AC AND DC arc flash calculation worksheets
♦ Training manual containing over 300 pages
♦ Jim’s 30 page Arc Flash Calculation Guide
♦ Many calculation examples and problems
♦ 16 hours of Continuing Education Credit
Part Two – Agenda
ARC FLASH STUDY BASED ON IEEE 1584 CALCULATIONS
Overview, Data Requirements, Where to Begin
ELECTRIC UTILITY COMPANY DATA
What data should be requested, minimum and maximum fault current, why not to use infinite bus calculations, what if the data can not be obtained?
SINGLE LINE DIAGRAM AND SYSTEM MODELING
Importance of the Up-to-Date Diagram, System Configurations, High vs. Low Fault Current, 125 kVA Transformer Exception, Motor Contribution
ARCING CURRENT CALCULATIONS, WORKSHEETS, EXAMPLE AND PROBLEMS
IEEE 1584 Arcing Current Calculations < 1kV and 1 kV to 15 kV, Defining the Arc Gap Based on Equipment Type, K1 for Arcing Current in a Box vs. Open Air
ARC FLASH DURATION – TIME CURRENT CURVES
Determining the Arcing Current Clearing time, 85% vs. 100%, 2 Second Cut Off Allowance, Time Current Curves, Arc Self Extinction
INCIDENT ENERGY CALCULATIONS, WORKSHEETS AND CLASS PROBLEMS
IEEE 1584 Incident Energy Calculations, Calculation Parameters, Calculation Factor Cf, Distance Exponent X, Working Distance, Grounded vs. Ungrounded, Effect of Equipment Type on Incident Energy Calculations
ARC FLASH BOUNDARY CALCULATIONS, WORKSHEETS AND CLASS PROBLEMS
Arc Flash Boundary Calculations Based IEEE 1584 Equations, Unusually Large Boundaries, Calculation Worksheets, Problem Solving
DC ARC FLASH CALCULATIONS, WORKSHEETS, EXAMPLES AND PROBLEMS
V-I Characteristics, DC Arc Resistance Calculations, DC Incident Energy Calculations, Box vs. Open Arc Calculations, Calculation Worksheets, Problem Solving
DETERMINING PPE REQUIRMENTS FROM INCIDENT ENERGY CALCULATIONS
Using calculated incident energy to determine PPE requirements. Simplifying the Selection
ARC FLASH WARNING LABELS
Simplifying the Arc Flash Labels, Minimum Requirements, Label Locations, ANSI Z535 Requirements, Incident Energy vs. Site Specific PPE vs. Arc Rating, Signal Words and Colors
RECOMMENDATIONS TO REDUCE THE ARC FLASH HAZARD
Increase Working Distance, Remote Operation, Maintenance Settings, Arc Resistant Equipment, Current Limiting Devices, “Holes” in Present Standards, The Electrically Safe Working Condition Paradox, Future Research and Developments
STEPS TO SIMPLIFY THE ARC FLASH CALCULATION STUDY
Jim’s “What would you like the answer to be?” Approach, Simplify the Selection of PPE and Arc Flash Boundary
QUESTIONS ABOUT THIS CLASS? CONTACT US AT 800.874.8883
Receive Answers to These Questions and More:
• How do I organize a study?
• Where do I obtain the required data?
• Do I need all data such as conductor lengths?
• How do I calculate AC incident energy, arcing current & arc flash boundary?
• What is the difference between low voltage and medium voltage calculations?
• How do I calculate DC incident energy from an arc flash?
• How do I calculate DC arc resistance and what is a V-I characteristic?
• How accurate are the IEEE 1584 calculations?
• Why do I also have to analyze arc flash during for minimum fault currents?
• What very important question do I ask the electric utility?
• Are time current curves a reliable way to determine arc flash clearing time?
• What if I have a low arcing current that causes a long clearing time?
• How do I use the NESC Table 410.1 and 410.2 for electric utility systems?
• Why do I use a comparison of 100% and 85% of the arcing current?
• Does the type of equipment make a difference in the calculations?
• What about grounded vs. ungrounded systems?
• How do I include motor contribution to the calculations?
• What are the Calculation Factor Cf and Distance Exponent Factor X?
• How can current limiting devices reduce the incident energy?
• Why use remote operation, arc resistant equipment, and maintenance switches?
• Why is selecting the correct working distance an important part of the calculations?
• What are Jim’s latest tests and what are plans for the next revision to IEEE 1584?
• Why is the L/E ratio ™ so important?
What is an Arc Flash Study?
As part of an arc flash study (Risk Assessment) the incident energy exposure level is determined based on the working distance of the employee’s face and chest areas from a prospective arc source. Arc-rated clothing and other PPE is selected with a rating sufficient for the incident energy exposure and shall be used by the employee based on the specific task. IEEE Std. 1584 tm, IEEE Guide for Performing Arc Flash Hazard Calculations is the method used globally for calculating the prospective incident energy.
NFPA 70E also requires determining the arc flash boundary, which is the distance from a potential arc source where the incident energy is 1.2 cal/cm2. This value is considered to be the point at which the onset of a second-degree burn occurs. Live work performed outside of the arc flash boundary does not require PPE, although the risk of some injury still exists.
The concept of these requirements is simple. At each location, the arc flash study is used to determine: The perspective incident energy exposure for a worker’s chest and face, the rating of PPE based on the perspective incident energy, the arc flash boundary.
Although the 2018 Edition of NFPA 70E provides more generalized PPE tables as a simplified alternative for PPE selection, an arc flash calculation study requires performing calculations to estimate the magnitude of incident energy exposure. These calculations are based on specific details, including the available short circuit current, device clearing time, grounding, arc gap distance, equipment type, and many other factors.
This information, as well as data regarding electric shock protection and approach limits, can be included on the arc flash warning labels placed on the equipment under study. Before conducting energized work, a qualified worker can refer to the label and obtain the data necessary for the shock hazard risk assessment and the arc flash hazard risk assessment as required by NFPA 70E.
Although an arc flash study can appear to be complex, it can be more manageable when broken down into basic steps as outlined in this training program.
Why Perform an Arc Flash Study?
According to OSHA 1910.132(d) The employer is responsible to assess the hazards in the work
place, select, have, and use the correct Personal Protective Equipment (PPE) and document the assessment. The use of NFPA 70E and other related industry consensus standards has been used to demonstrate whether an employer acted reasonably when there is a possible OSHA enforcement action taken.
So although NFPA 70E is not directly part of OSHA standards, it can be used as evidence of whether an employer acted reasonably in complying with OSHA standards and addressing “recognized hazards”.
There are more specific links within the OSHA standards as well. A typical example is found in 1910.335, Safeguards for personnel protection which requires: “(a)(1)(i) Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed.”
This regulation requires that employees must be properly protected from potential electrical hazards, by using adequate PPE, but it does not provide specific detail of what specific personal protective equipment is necessary to achieve the objective. It might be considered that based on this generalized statement, the selection of the correct PPE is open to interpretation however, this would be incorrect and an Arc Flash study should be performed.
For questions, registration information or to discuss holding this class at your location as an on-site training program, contact our Program Director at 800.874.8883
Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267