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Arc Flash 2012 Session 345

Published Jan 13, 2014 in Business & Management
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Presentation Slides & Transcript

Presentation Slides & Transcript

Arc Flash 2012NFPA 70EIEEE 1584

Electrical equipment relies on both conductive and insulating materials. Insulating materials include rubber and plastic materials, as well as AIRWhen an electrical fault occurs, the air breaks down, and an arc is produced. Energy is given off in the form of light (radiant)sound (blast)a shock wave.The radiant energy can ignite fabrics, burn skin, damage eyesightThe blast can fragment equipment, expel shrapnel, and damage hearingWhat is Arc Flash?

One to three worker per day is estimated to die from flash incidents daily. Often, the unlucky ones are the ones who survive.In 1976, National Fire Protection Association (NFPA) convened a panel to study the matter, and in 1979, issued the first edition of the NFPA 70E Standard.Both Recognized and quantified Arc Flash in NFPA 70EIn 1999, OSHA started to recognize and enforce NFPA 70E in Ohio and Michigan. Other states followed suitIn 2002, the Institute of Electrical and Electronic Engineers (IEEE) published their document, IEEE 1584Arc flash compliance is now mandatory for certain types of equipment (new installations of medium voltage gear)The Human Toll

The two standards provide slightly differing resultsBoth are based on empirical formulas Empirical formulas are based on modeling of observed laboratory resultsExtremely good estimatesTrend appears to be:NFPA leaning toward strictly “Safe Work Practices” & PPE and application standardsIEEE leaning to become the analytical standardFor now, most agencies focus on NFPANFPA 70E Vs. IEEE 1584

OSHA Enforcement OSHA Act of 1970 - No reference to NFPA 70E or certainly IEEE 1584. Says only:1910.269 (l) (6) (iii) The employer shall ensure that each employee who is exposed t hazards of flames or electric arcs does not wear clothing that, when exposed to flames or electric arcs, could increase the extent of injury that would be sustained by the employee.OSHA Act of 1970, 5. DutiesEach EmployerShall furnish to each of his employees employment and a place of employment which are free from recognized hazards that a causing or likely to cause death or serious physical harm to his employees;With the advent of NFPA 70E in 1979, Arc Flash was recognized as a hazard, and therefore Section 5 (a) (1) enforces protection of employees from arc flash.In the State of Ohio, the OSHA enforcement officers are citing employers for lack of a comprehensive arc flash safety program.

IntensityIs Arc Flash Really that intense?Arc Flash Blanket25,000 Amp TestCotton/Polyester Shirt Test:8,400 Amp test stand

Capacitor Bank FailureIndustrial Facility: Actual fault reached ~65,000 Amps Peak or ~45,000 Amps

What Can Be Done?Personal Protective Equipment (PPE)50 Cal/cm2 Hood Test:25,000 Amp test stand

Business Reasons:OSHA Mandates – it’s not really a choiceFines for non-compliance can reach several thousand per incident.Personal liability issues for supervisors and managersSocial Reasons:It’s the right thing to doBurn injuries are arguably the worst type of injurySurvival can be a curseHigh divorce rate of victimsEmployer’s/supervisor’s responsibility…. But why?

Two Methods contained in the standard:Tabled Methods – Task and circumstance orientedPlus – Reasonably straight forwardMinus – More PPE than would be required with actual calculation for most areas, not enough in othersConclusion – It is a compromise, but better than nothingCalculation – Engineering SolutionPlus – More accurateMinus – Requires engineering expertiseConclusion – Better method, but can be costly Dealing with Arc Flash

Calculating Arc Flash IntensityStep one – short circuit analysis: Magnitude and DurationUse “point to point” methodGE, BussmannComputer ProgramsSKM, EDSA, ETAP, Easy Power and othersCalculate three phase symmetrical available fault at relevant points.Step two – Calculate flash intensity, determine the PPE required within the approach distanceStep three – Calculate approach distancesStep four – Documentation:Labeling switchgear/preparation of central document repositoryTrainingSafety Program development Integration

Arc Assessments are dependent on not only the fault MAGNITUDE, but fault DURATIONHow long the fault is present has a significant impact on the flash intensity(Something we can actually do something about)For engineers, Arc Flash can create a conflict between coordination/reliability issues and personnel safetyFault Clearing Time

Circuit breaker performance1,600 amp frame DS416; ~70 ms or < 5 cycles600 amp Siemens ND ~.018 seconds or just over 1 cycleInstantaneous Settings

Fairly simpleMinimum Melt lineMaximum Clear line400 Amp RK1 FuseCan clear in ¼ cycleHave Current Limiting CapabilityFuse Curves

Approach BoundariesQualified IndividualsThose with formal training who are competent to work on electrical equipmentUnqualified IndividualsThose individual with no specific training to work on live electrical equipmentInsulated tools – ASTM F1505 Compliant

Limited Approach Boundary restrictions (750 volts and below):Unqualified persons must remain outside the limited approach boundary (3.5 to 10 ft).Bear in mind that this may put the unqualified person at risk of burn injuryThe Flash boundary can exceed the limited approach boundary. If the work is within the Flash boundary, but outside the limited approach boundary, protective clothing is required.If an Unqualified person is near the boundary, they shall have a person available to watch him/her for inadvertent approach.Qualified person may enter the limited approach boundary, but: cannot enter the restricted approach boundary unless insulatedFlash protection must be in place All boundaries are removed and unqualified person can work on electrical equipment that is “made safe” by Lock-Out-Tag-Out (LOTO).Qualified person may enter the Restricted Approach boundary if appropriate shock protection equipment is in place.Qualified person may enter the Prohibited Approach boundary only if necessary, a job briefing is done, the risks considered, appropriate insulated tools are used, and there are no other alternativesQualified Versus Unqualified

Basic Clothing TypesMan-made fibers to be avoided:Nylon, polyester, polypropylene, acetate, blendsNatural Fibers should be favoredCotton, wool, silk, rayon, blendsBeware of thinking that natural fibers conform to OSHA 1910.269. These materials are flammableSpecialty fibersNomex, Wextex Indura Ultrasoft, other fire resistant cotton products and fire resistant blendsAll are Self Extinguishing

ComponentsBlast SuitBib OverallsJacket HoodInsulating GlovesRain SuitsArc Flash GlovesFace ShieldsBlanketsNote:Welding garments and equipment do not provide protection from arc flash

Know the LimitationsEquipment should be used within its design limitationsUsing flash protective equipment beyond its limits can become a hazard itselfBecomes a violation of OSHA 1910.269 (l) (6) (iii) “The employer shall ensure that each employee who is exposed t hazards of flames or electric arcs does not wear clothing that, when exposed to flames or electric arcs, could increase the extent of injury that would be sustained by the employee.”

Provide ProtectionSafety is non-negotiableAssure that the worker will be protected from:Radiant energySuper-heated GasesSound Pressure Level (SPL)Accommodate Human IssuesSafety must be sensible (it can be)Excessive requirements invite non-compliancePPE can be hot, especially in industrial environmentsLimits vision, mobility, dexterityCompeting Issues

Change what you do and how you do it. Think “Outside the Box”Alternatives:Voltage readings – Install panel meters, fused leadsCurrent Readings – new “fork type” current metersRemote resets, Remote programmingObservation portsBreaker/ MCC Racking – Remote Racking devicesRemote Electrical racking means Additional barriers CompartmentalizingChek-Volt tm InsertsWork Methods

Strategy to ProtectionComplicated

SimplificationSimplification invites complianceDaily wear available up to 15 cal/cm2Face shields up to 12 cal/cm23 levels:< 1.2 cal/cm2 (Cotton Clothing), leather gloves, eye protection> 1.2 cal/cm2 – 8 cal/cm2 (Cotton underwear plus 8 cal/cm2 FR shirt and pants, 8 cal/cm2 face shield, 8 cal/cm2 balaclava (new for 2012), hard hat, leather gloves, leather shoes)> 8 – 65 cal/cm2 (Cotton underwear plus 65 cal/cm2 hood, jumpsuit or jacket and overalls, hearing protection, eye protection hard hat, leather gloves, leather shoes)>65 No EntryPersonal Garments

Word on Category “0”Category “0” is anything but “0”A Cat 0 incident is life changingCan be emotionally debilitatingCan cause painful injuriesCould be disablingIs anything BUT “nothing”Estimated Category 1 event

Application of PPE Calculated Arc Flash Values are in force:When bolted panel covers are off exposing internal componentsHinged Panel or MCC doors are open exposing energized componentsIncludes Fused disconnect and bus plugs where barriers will not contain arc blastIncludes switchgear and medium voltage device switching When bolted covers are on:Category “0” clothing (Long sleeve cotton shirt, pants, gloves, eye protection) are required to operate main panel switches, circuit breakers Gloves recommended for all other panel breakersEven includes lighting circuit breakers

ImplementationLabeling GearDetailed placard with complete Arc Flash Hazard informationOutlines hazard and PPE requirementsDate of last reviewEquipment IdentificationCentral repository for hazard assessmentImplement “Hot Work” Authorization systemTrainingInternal personnel (maintenance, engineering, production)External contractors (must be documented, new for 2012)Retraining every 3 years (new for 2012)AuditingAudit individual PPE use required every year per 2012 NPFA 70EEmployers responsibility to assure that standard is followedAudit program now required every 3 years per 2012 NPFA 70EAssessment Re-Assessment every 5 years (130.5)

Job BriefingEither by the Superior, Job/Project leader, or self briefedSurveyPlanActReviewCommunicate

Work PermitFor non-routine energized work only

Employers Responsibility NFPA 110.3 (B) The electrical safety program shall be designed to provide an awareness of the potential electrical hazards to employees who work in an environment with the presence of electrical hazards. The program shall be developed to provide the required self-discipline for all employees who must perform work that may involve electrical hazards. The program shall instill safety principals and controls.Not enough to simply put in place a safety program

Thank You!