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ARC FLASH PROTECTION AND SAFETY MEASURES
September 2010
IntroductionHazards of Electrical EnergyElectrical Safety ProgramSafety-Related Work PracticesElectrical Safety Procedures
Presented By:Ken Schmerber, MS, CIH, CSPPrincipal EHS ConsultantHellman & Associates, Inc.303-384-9828kschmerber@ehscompliance.com
INTRODUCTION
OSHAs 29 CFR 1910.332(a) - Requires training when employees face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of 1910.303 through 1910.308.
OSHAs 1926.416(a)(1) - No employer shall permit an employee to work in such proximity to any part of an electric power circuit that the employee could contact the electric power circuit in the course of work, unless the employee is protected against electric shock by de-energizing the circuit and grounding it or by guarding it effectively by insulation or other means.
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INTRODUCTION
To be Considered a Qualified Person:Safety-related work practices that pertain to their job assignments.The skills and knowledge necessary to:
Distinguish exposed live parts from other parts of electric equipment; andDetermine the nominal voltage of exposed live parts.
Appropriate clearance distances for the corresponding voltages to which they will be exposed.Construction and operation of the equipment and the hazards involved.Specific hazards associated with electrical energy.Relationship between electrical hazards and possible injury.Applicable emergency procedures.
INTRODUCTION
Regulations/Standards ( 50 Volts):OSHA 29 CFR 1910, Subpart S, Electrical
1910.331, Scope1910.332, Training1910.333, Selection and Use of Work Practices1910.334, Use of Equipment1910.335, Safeguards for Personal Protection
National Fire Protection Association (NFPA) 70E, Standard for Electrical Safety in the Workplace, 2009 Edition
Chapter 1 - Safety-Related Work PracticesChapter 2 - Safety-Related Maintenance RequirementsChapter 3 - Safety Requirements for Special EquipmentAnnexes A - O
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INTRODUCTION
NFPA Chapter 1, Safety-Related Work Practices Article 100 - DefinitionsArticle 110 - General Requirements for Electrical Safety-Related Work PracticesArticle 120 - Establishing an Electrically Safe Work ConditionArticle 130 - Work Involving Electrical Hazards
INTRODUCTION
Energized Electrical Work Permit
Electrical Safety Program
Hazard/Risk Category
Refers to Subpart I
Personal Protective Equipment
Approach Boundaries ALL Work
Qualified Person/Training
Working on Live Parts
NFPA 70E Chapter 1
Subpart SReferenceNFPAOSHA
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INTRODUCTION
HAZARDS OF ELECTRICAL ENERGY
Hazards include:Shock;Electrocution;Arc Flash/Blast; andBurns.
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Why is arc flash dangerous?An arc is a source of intense heat, light, sound, and pressure!
Colorado in July/August: 100 F Surface of the Sun: 8,540 FArc at arc terminals: 35,540 F
HAZARDS OF ELECTRICAL ENERGY
Physical Effects of Arc BlastMetal vapor and air expand very rapidly due to arc heating.Pressure wave (~740 mph; 2,000 psi; ~ 165 dB) knocks worker away from arc:
Good: removes personnel from heat sourceBad: removes personnel from ladderEardrum ruptureBlindnessLung damageDeath!
Molten metal droplets:Can ignite clothingCause burns
HAZARDS OF ELECTRICAL ENERGY
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HAZARDS OF ELECTRICAL ENERGY
How hazardous can it be?
HAZARDS OF ELECTRICAL ENERGY
Annual Preventative Maintenance Incident
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HAZARDS OF ELECTRICAL ENERGY
Live Breaker Replacement Incident
HAZARDS OF ELECTRICAL ENERGY
Breaker Racking
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GeneralImplement overall program that is appropriate to manage the degree of hazardElectrical safety procedures are one componentLO/TO also plays a critical role
Safe Work Procedures Hazard Analysis
Coordination StudyShock and Arc-Flash Analysis
Job Briefing Personal Protective Equipment Training Auditing
ELECTRICAL SAFETY PROGRAM
ELECTRICAL SAFETY PROGRAM
OSHA 29 CFR 1910.333 Safety related work practices shall be employed to
prevent electric shock or other injuries resulting from either direct or indirect electrical contact.
Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible.
Verification that equipment is deenergized can be hazardous.
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When is it acceptable to work on energized equipment?
When it involves:Interruption of life support systems;Deactivation of emergency alarm systems;Shutdown of hazardous location ventilation; andRemoval of illumination.
Or is infeasible:Diagnostics and testing (e.g., start-up and troubleshooting); andPart of continuous process segment.
ELECTRICAL SAFETY PROGRAM
Hazard AnalysisCoordination StudyElectrical Hazard Analysis
Shock HazardProcess described in NFPA 70E 130.2, Approach Boundaries to Energized Electrical Conductors or Circuit Parts
Arc Flash HazardProcess described in NFPA 70E 130.3, Arc Flash Hazard AnalysisAlternative is to use the PPE requirements in NFPA 70E 130.7(C)(9). The table can be used if system meets the limitations in the Note section at the end of the table.
ELECTRICAL SAFETY PROGRAM
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Hazard/Risk Evaluation Procedure
ELECTRICAL SAFETY PROGRAM
ELECTRICAL SAFETY PROGRAM
Table 130.7(C)(9), Hazard/Risk Classification
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ELECTRICAL SAFETY PROGRAM
Table 130.7(C)(9), Notes
ELECTRICAL SAFETY PROGRAM
Table 130.7(C)(10), PPE
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ELECTRICAL SAFETY PROGRAM
Table 130.7(C)(10), Notes
ELECTRICAL SAFETY PROGRAM
Table 130.7(C)(11), Protective Clothing Characteristics
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ELECTRICAL SAFETY PROGRAM
Annex D, Incident Energy and Flash Protection Boundary Calculation Methods
ELECTRICAL SAFETY PROGRAM
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ELECTRICAL SAFETY PROGRAM
Equipment shall be field marked with a label containing the available incident energy or required level of PPE.
Procedures (Routine)Purpose of taskQualifications and number of employees involvedHazardous nature and extent of taskLimits of approachSafe work practices to be utilizedRequired PPE including insulating materials and toolsElectrical diagramsEquipment detailsReference data
ELECTRICAL SAFETY PROGRAM
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Job Briefing Form (Non-Routine)
ELECTRICAL SAFETY PROGRAM
Energized Electrical Work Permit (Non-Routine)Used when an electrical system cannot be placed in an electrically safe work condition.
ELECTRICAL SAFETY PROGRAM
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LOTO Approach boundaries PPE and inspection Others
SAFETY RELATED WORK PRACTICES
Approach Boundaries and PPEShock Protection
Limited;Restricted; andProhibited.
Flash ProtectionDistance at which the incident energy is 1.2 cal/cm2 (i.e., point at which second degree burns may occur).
SAFETY RELATED WORK PRACTICES
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Limits of Approach (Figure C-1-2.4)
SAFETY RELATED WORK PRACTICES
SAFETY RELATED WORK PRACTICES
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SAFETY RELATED WORK PRACTICES
Personal Protective Equipment
SAFETY RELATED WORK PRACTICES
Use the left hand rule Open cabinets from hinged side Ensure there is adequate illumination No blind reaching Do not use over current protection devices as
switches Use shielding for enclosed spaces No use of conductive materials or equipment
such as metal ladders and apparel Housekeeping
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ELECTRICAL SAFETY PROCEDURES
Required PPE
ELECTRICAL SAFETY PROCEDURES
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Procedure
ELECTRICAL SAFETY PROCEDURES
SUMMARY
OSHA and NFPA 70E 50 VQualified Worker
Hazards of Electrical EnergyShockArc Flash
Electrical Hazard AnalysisDetermines PPE level
Safety-Related Work PracticesWork deenergizedLOTOPPE if working energized
Electrical Safety ProgramESPsEnergized Work Permit