5 Electric Shock LOW VOLTAGE DOES NOT MEAN LOW HAZARD Exit Entrance Received when current passes through the bodySeverity of the shock depends on:Path of current through the bodyAmount of current flowing through the bodyLength of time the body is in the circuitLOW VOLTAGE DOES NOT MEAN LOW HAZARDGroundExit
8 OSHA Standards 1910 Subpart S – Electrical – .308 = Safe installation– .330 = Reserved– .335 = Work practices– .398 = Reserved– DefinitionsAppendix A – Reference Documents
9 ScopeApplies to qualifed and unqualified employees performing work on:Premises wiringConnecting to supplyOther wiringOptical fiber cableDoes NOT apply to generation, distribution, or communication (specific standards for these)Refers to for definition of qualified persons.
10 “Qualified Person” – OSHA 1910.399 One who has received training in and has demonstrated skills and knowledge in the construction and operation of electrical equipment and installation and the hazards involved.
11 TrainingEmployees who face a risk of electric shock that is not reduced to a safe level installation requirements must be trained.Occupations in Table S-4 must be trained.Other employees if they face a risk of shock.
12 Table S-4 Blue collar supervisors Electrical and electronic engineers Electrical and electronic equipment assemblersElectrical and electronic techniciansElectriciansIndustrial machine operatorsMaterial handling equipment operatorsMechanics and repairersPaintersRiggers and roustaboutsStationary engineersWeldersFootnote(1) Workers in these groups do not need to be trained if their work or the work of those they supervise does not bring them or the employees they supervise close enough to exposed parts of electric circuits operating at 50 volts or more to ground for a hazard to exist.
13 1910.332 Training Training focused on: Recognizing live parts Determining voltage of live partsClearance distances specified in
14 1910.333 Selection and Use of Work Practices Focused on work near exposed energized or potentially energized parts.Locking and taggingDeenergizationVerifying deenergized conditionReenergizingOverhead power lines (clearance distances)IlluminationSeveral other tasks
15 1910.333 Selection and Use of Work Practices "Deenergized parts." 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 due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
16 1910.334 Use of Equipment Covers things like: Portable equipment Plugs and cordsReclosing circuitsInspection of equipment
17 1910.335 Safeguard for Personnel Protection Personal Protective EquipmentMust use when exposedMaintenanceInspectionInsulated hand toolsGuarding of exposed parts during work
19 Electrical HazardsNFPA 70E – A dangerous condition such that contact or equipment failure can result in:Electric ShockArc flash burnThermal burnArc blast
20 Arc Flash & Arc BlastArc Flash – electrical short circuit that occurs when air flashes from an exposed live conductor, to either another conductor or to ground.Arc Blast – pressure wave caused by the arc flash.
21 Arc Flash/Blast Concentrated energy explodes outward High intensity flashTemperatures can reach 35,000Pressure wave can reach 200lbs/sq. inchVaporize conductors and copper and explode particles like buckshot.
22 Arc Flash Effects Severe burns Broken bones Vision damage Hearing loss Brain/internal injuriesPunctures and lacerationsDeath
23 Causes of Arc Flash Improper training Improper work procedures Dropped toolsAccidental contact with electrical systemsInstallation failureInadequate SCCRVoltage testing with inappropriate equipment
24 Causes of Arc Flash (cont.) Buildup of dust, corrosion on insulating surfacesImproper maintenanceSparks produced during racking of breakers, replacement of fuses and closing into faulty lines.Inattentiveness/Overconfidence
25 We’re in Missouri, so show me! Racking a BreakerBreaker Box Demonstration
26 “Qualified Person” – NFPA 70 One who has the skill and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.May be considered qualified with respect to certain equipment & method but still unqualified for others.
27 Qualified Persons Training Requirements Understand specific electrical hazardsKnowledgeable of the construction and operation of the equipmentIdentify & understand the relationship between electrical hazards and possibly injuryDistinguish exposed live partsAble to determine voltage of live partsUnderstands and complies with arc flash and shock hazard boundaries.
28 Qualified Persons Training (cont.) Proper use of precautionary techniquesPPE, including arc-flash & shock protectionInsulated toolsDemonstrate how to select and use a voltage meterDecision-making process used to determine the degree and extent of the hazard
29 Justification for Work NFPA 70E 130.1 Energized electrical conductors and circuit parts to which an employee might be exposed shall be put into an electrically safe work condition before an employee works within the Limited Approach Boundary of those conductors or parts.Unless – the employer can demonstrate that de-energizing introduces additional hazards or is infeasible.Interruption of life support systemsDeactivation of emergency alarm systemsShutdown of hazardous location ventilation systemsCircuits and conductors that operate at less than 50 volts
30 Justification for Work NFPA 70E 130.1 (cont.) Other work that may be performed within the limited approach boundary of exposed energized electrical conductors or circuits:TestingTroubleshootingVoltage measuring
31 Safe Work Practices De-energize-Lockout Policy Don’t wear conductive apparelWork area must be illuminatedNever reach into blind spotsDon’t allow conductive liquids near electrical work or equipmentBuddy system (over 1,000 volts, work in pairs)Do not defeat electrical interlocksUse nonconductive ladders
32 Steps to NFPA 70E Compliance Have an arc hazard survey completed.Implement any recommendations to reduce the hazards.Develop and implement a labeling system.Determine what tasks will be performed and at what hazard category.Train (qualify) employees and provide PPE.
33 Arc Hazard Survey Conducted by an engineering firm Survey includes: Single line diagram of electrical systemIncident energy levelsCurrent limiting device coordinationCalculates a hazard risk category and approach boundariesDevelops recommendations to reduce high hazard risk categories
34 Reduce the hazards! Some examples: Change fuses Develop a maintenance programAdjust circuit breakersInstall additional disconnects
39 NFPA 70E Approach Boundaries (cont.) The qualified worker is responsible for ensuring physical barriers are in place and all approach boundaries are enforced during work.Warning label provides boundary informationFlash Boundary – 4 ft. or calculatedLimitedProhibitedRestricted
40 Specific Tasks Troubleshooting only! NO “WORK!” Checking / replacing fusesChecking motor startersChecking amp drawChecking relays
42 Arc Flash Hazard Training Labeling systemGlove selection and testingShock protectionArc flash rated clothingArc flash protection
43 Glove Labeling Chart Choose the right glove by voltage rating
44 Voltage-rated Gloves Salisbury video First line of defense Choose the right sizeLeather protectors must be worn over the rubber glovesGloves must be testedBefore first issue and every 6 monthsIf tested, but not issued for service, glove may not be put into service unless tested within previous 12 months.Checked before useRoll-up testInflator testSalisbury video
45 Arc-Rated FR Clothing & PPE LayeringOuter layers must be flame resistantUnder layers must be non-meltingFit – Clothing shall fit properly (loose), w/ least interferenceCoverage – Clothing must cover potentially exposed areas (wrist, neck)Care & MaintenanceInspect before useLaunder according to mfg’s instructions*Photo courtesy of Salisbury
46 PPE - Hazard Risk Category 0 0-1.2 cal/cm2 100% cotton long sleeve shirtLong pantsSafety glassesHearing protectionLeather and insulated gloves (as required)Leather work boots
47 PPE - Hazard Risk Category 1 1.2 - 4 cal/cm2 4+ cal long sleeve shirt & long pants (or) coverallsHardhatSafety glassesArc rated faceshieldHearing protection (inserts)VR glovesLeather glovesLeather work boots
48 PPE - Hazard Risk Category 2 4 - 8 cal/cm2 8+ cal long sleeve shirt & long pants (or) coverallsHardhatSafety glassesArc rated faceshieldHearing protection (inserts)VR glovesLeather glovesLeather work boots
49 PPE - Hazard Risk Category 3 8 - 25 cal/cm2 25+ flashsuit w/ hood over long sleeve shirt and long pantsSafety glassesArc rated faceshieldHearing protection (inserts)VR glovesLeather glovesLeather work boots
50 PPE - Hazard Risk Category 4 25 - 40 cal/cm2 40+ flashsuit w/ hood over FR long sleeve shirt and long pantsSafety glassesArc rated faceshieldHearing protection (inserts)VR glovesLeather glovesLeather work boots
51 Hands-On Training How to use a multi-meter Set up a safe scenario Lockout upstream before class!Trainee performsUnacceptable performance = NOT qualified!