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An Engineer’s Guide to OSHA’s
New Recommendations
for Arc Flash Studies
Before We Start
q  This webinar will be available at
www.windpowerengineering.com & email
q  Q&A at the end of the prese...
Moderator Presenter
Paul Dvorak
Windpower Engineering
& Development
Tahnee Miller
Ulteig
An Engineer’s Guide
to OSHA’s New
Recommendations for
Arc Flash Studies
Tahnee Miller, PE
Ulteig
tahnee.miller@ulteig.com
Objective
•  Explain the impact of a new OSHA filing which affects the
calculation methods of arc flash risk assessment fr...
Overview
•  Basics of arc flash
•  How arc flash is calculated
•  Impact of OSHA 29 CFR Parts 1910 and 1926 final ruling
•...
Arc Flash Basics
•  Defined by NFPA 70E-2015: a dangerous condition
associated with the possible release of energy caused ...
Calculation Methods
•  NFPA 70E-2015
•  IEEE 1584
•  Ralph Lee Method
•  ANSI/IEEE C2 NESC, Section 410
•  Etc.
OSHA 29 CFR 1910/1926
•  Released in April 2014, became effective in July 2014
•  Replaces the incorporation of these cons...
NFPA 70E-2012 Annex D
(Lee Equation)
•  <= 600 V
o  Acceptable for open-air arcs (though not typically used at this voltag...
Doughty, Neal, and Floyd
•  <= 600 V
o  Conservative, but reasonable
•  > 600 V
o  Not acceptable
o  Testing was performed...
IEEE Std 1584b-2011
•  Refers to IEEE Std 1584-2002 including both amendments
•  <= 15 kV
o  Reasonably estimates incident...
ARCPRO
•  Based on tested heat flux data in lab
•  <= 15 kV
o  Can be used as long as arc is single phase and open air
o  ...
Incident Energy
Calculation Method
600 V and Less2 601 V to 15kV2 More than 15 kV
1Φ 3Φa 3Φb 1Φ 3Φa 3Φb 1Φ 3Φa 3Φb
NFPA 70...
Table 1 Notes
1Φ: Single-phase arc in open air
3Φa: Three-phase arc in open air
3Φb: Three-phase arc in enclosure (box)
Y:...
Incorporating Ruling
•  Equipment <= 15 kV
o  IEEE Standard 1584b-2011
•  Equipment > 15 kV
o  ARCPRO calculations adjuste...
Thank You
Tahnee Miller, PE
Ulteig
tahnee.miller@ulteig.com
Questions?
Paul Dvorak
Windpower Engineering & Development
pdvorak@wtwhmedia.com
Twitter: @windpower_eng
Tahnee Miller
Ult...
Thank You
q  This webinar will be available at
www.windpowerengineering.com & email
q  Tweet with hashtag #WindWebinar
q...
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An Engineer’s Guide to OSHA’s New Recommendations for Arc Flash Studies

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There are several calculation methods available to calculate arc flash risk in terms of incident energy, but until recently, there was no clear direction from OSHA about which calculation method was preferred. Because of this, several methods were used.

The new final ruling of OSHA 29 CFR Parts 1910 and 1926 provides recommendations for calculation methods to use for incident energy for equipment of different voltages. This webinar summarizes the ruling’s recommendations for incident energy calculations and the impact these recommendations may have on arc flash risk assessments from the perspective of a consultant engineer.

View this webinar to learn:
-An overview of current incident energy calculation methods
-Which incident energy calculation method OSHA recommends for certain equipment
-How OSHA recommendations for incident energy calculation methods may be incorporated into arc flash studies

Published in: Engineering
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An Engineer’s Guide to OSHA’s New Recommendations for Arc Flash Studies

  1. 1. An Engineer’s Guide to OSHA’s New Recommendations for Arc Flash Studies
  2. 2. Before We Start q  This webinar will be available at www.windpowerengineering.com & email q  Q&A at the end of the presentation q  Hashtag for this webinar: #WindWebinar
  3. 3. Moderator Presenter Paul Dvorak Windpower Engineering & Development Tahnee Miller Ulteig
  4. 4. An Engineer’s Guide to OSHA’s New Recommendations for Arc Flash Studies Tahnee Miller, PE Ulteig tahnee.miller@ulteig.com
  5. 5. Objective •  Explain the impact of a new OSHA filing which affects the calculation methods of arc flash risk assessment from the perspective of a consultant engineer.
  6. 6. Overview •  Basics of arc flash •  How arc flash is calculated •  Impact of OSHA 29 CFR Parts 1910 and 1926 final ruling •  Incorporating OSHA ruling into arc flash studies
  7. 7. Arc Flash Basics •  Defined by NFPA 70E-2015: a dangerous condition associated with the possible release of energy caused by an electric arc. •  An arc flash risk assessment must include: o  Incident Energy at a given working distance o  Arc Flash Boundary o  Personal Protective Equipment (PPE) that must be worn inside the AF boundary
  8. 8. Calculation Methods •  NFPA 70E-2015 •  IEEE 1584 •  Ralph Lee Method •  ANSI/IEEE C2 NESC, Section 410 •  Etc.
  9. 9. OSHA 29 CFR 1910/1926 •  Released in April 2014, became effective in July 2014 •  Replaces the incorporation of these consensus standards with a set of recommendations •  Appendix E to Subpart V of Part 1926 summarizes OSHA’s recommendations for calculation methods for equipment •  Includes detailed comparison of the options o  Summary on following slides
  10. 10. NFPA 70E-2012 Annex D (Lee Equation) •  <= 600 V o  Acceptable for open-air arcs (though not typically used at this voltage) •  > 600 V and <= 15 kV o  Reasonable, but conservative, so PPE will be heaver and bulkier than needed •  > 15 kV o  Should only be used to estimate incident energy if the employee exposure is calculated to be less than 2 cal/cm2 •  Estimates incident energy levels for three-phase arcs
  11. 11. Doughty, Neal, and Floyd •  <= 600 V o  Conservative, but reasonable •  > 600 V o  Not acceptable o  Testing was performed exclusively with an electrode spacing of 32 mm at 600 V
  12. 12. IEEE Std 1584b-2011 •  Refers to IEEE Std 1584-2002 including both amendments •  <= 15 kV o  Reasonably estimates incident energy o  Accounts for differences between single-phase and three-phase arcs and between arcs in open air or enclosed arcs •  > 15 kV o  Outside the range of the standard and thus not recommended
  13. 13. ARCPRO •  Based on tested heat flux data in lab •  <= 15 kV o  Can be used as long as arc is single phase and open air o  Conversion factors for three-phase or enclosed arcs are not verified •  > 15 kV o  Same issues as <= 15 kV, but since there is no reasonable alternative, OSHA considers this method as a reasonable estimate if the conversion factors are used •  NESC tables in Section 410 based on ARCPRO calculations
  14. 14. Incident Energy Calculation Method 600 V and Less2 601 V to 15kV2 More than 15 kV 1Φ 3Φa 3Φb 1Φ 3Φa 3Φb 1Φ 3Φa 3Φb NFPA 70E-2012 Annex D (Lee Equation) Y-C Y N Y-C Y-C N N3 N3 N3 Doughty, Neal, and Floyd Y-C Y Y N N N N N N IEEE Std 1584b-2011 Y Y Y Y Y Y N N N ARCPRO Y N N Y N N Y Y4 Y4 Table 1 – Selecting Reasonable Incident-Energy Calculation Method1
  15. 15. Table 1 Notes 1Φ: Single-phase arc in open air 3Φa: Three-phase arc in open air 3Φb: Three-phase arc in enclosure (box) Y: Acceptable: produces a reasonable estimate of incident heat energy from this type of electric arc N: Not acceptable: does not produce a reasonable estimate of incident energy from this type of electric arc Y-C: Acceptable: produces a reasonable, but conservative, estimate of incident heat energy from this type of electric arc
  16. 16. Incorporating Ruling •  Equipment <= 15 kV o  IEEE Standard 1584b-2011 •  Equipment > 15 kV o  ARCPRO calculations adjusted with conversion factors for three-phase arcs in open air or in an enclosure o  NESC Section 410 tables (based on ARCPRO test data)
  17. 17. Thank You Tahnee Miller, PE Ulteig tahnee.miller@ulteig.com
  18. 18. Questions? Paul Dvorak Windpower Engineering & Development pdvorak@wtwhmedia.com Twitter: @windpower_eng Tahnee Miller Ulteig tahnee.miller@ulteig.com
  19. 19. Thank You q  This webinar will be available at www.windpowerengineering.com & email q  Tweet with hashtag #WindWebinar q  Connect with Windpower Engineering & Development q  Discuss this on the EngineeringExchange.com

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