Arc Flash Protection and Safety Measures 0910-Schmerber

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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, [email protected]

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


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


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How hazardous can it be?


Annual Preventative Maintenance Incident

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Live Breaker Replacement Incident


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


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.


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.


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Hazard/Risk Evaluation Procedure



Table 130.7(C)(9), Hazard/Risk Classification

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Table 130.7(C)(9), Notes


Table 130.7(C)(10), PPE

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Table 130.7(C)(10), Notes


Table 130.7(C)(11), Protective Clothing Characteristics

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Annex D, Incident Energy and Flash Protection Boundary Calculation Methods


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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


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Job Briefing Form (Non-Routine)


Energized Electrical Work Permit (Non-Routine)Used when an electrical system cannot be placed in an electrically safe work condition.


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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).


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Limits of Approach (Figure C-1-2.4)



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Personal Protective Equipment


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


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Procedure


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

Arc Flash Protection and Safety Measures 0910-Schmerber

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