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ELECTRICAL SAFETY

ELECTRICAL SAFETY. Safety and Health Officer Certificate Programme. Session/ LessonPlans. OBJECTIVES. St a te the d e f i n i t i o n o f c u rr e n t , v o l t a n d o h m E x p lai n 4 h a z a r d s r e la t e d t o e l ec t r i c i t y

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ELECTRICAL SAFETY

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  1. ELECTRICAL SAFETY Safety and Health Officer Certificate Programme

  2. Session/LessonPlans

  3. OBJECTIVES • Statethedefinitionofcurrent,voltandohm • Explain4hazardsrelatedtoelectricity • Explain2basicpreventivemeasuresinelectricalsafety

  4. OBJECTIVES • Stateatleast4considerationsinthesafeuseofelectricity • Identifystatutoryrequirementsrelatedtoelectricalsafety

  5. SCOPE • Definition • Electricalinstallation • Hazardandeffectsof electriccurrents • Principles of electrical safety • Safeuse of electricity • Electricalsafetycontrols • Conclusion

  6. ELECTRICITY • Aformof energythatisefficient andsimple • Usages: • Lighting • Heating • Energyuse (ovenetc)

  7. TERMINOLOGY • Electricisaformofenergy that is • producedfromtheflowofelectrons. • Itisageneraltermthatincludesenergy relatedtoelectricitycharges,whetherstatic ordynamic.

  8. FACTORS THAT INFLUENCE ELECTRICITY • Volt • Theforceofelectricenergy • Ampere • Actualflowof electricity • Ohm • Characteristicforthecircuit orrouteofwhich electricityflows andoffersresistancetothecurrent

  9. ADVANTAGES OF ELECTRICITY • Cost effective • Clean • Easytouse • Doesnotrequirestorage

  10. CHARACTERISTICS OF ELECTRICITY • Cannotbeseen • Cannotbeheard • Cannotbesmelt

  11. ELECTRICAL INSTALLATIONS • Includes: • Circuit • Conductor • Mainswitch,localanddistributingboard • Circuitbreakers • Fuse • Socketandplug

  12. ELECTRICAL INSTALLATIONS - CIRCUIT • Whereelectriccurrent flows • Providesthesource of energy • Is complementedbyuse of aconductorto allowcontrol of current

  13. ELECTRICAL INSTALLATIONS - CONDUCTOR • Comprisesof: • Internally:Metal whichallowstheflow ofelectricity • Externally:Rubber– forinsulation

  14. ELECTRICAL INSTALLATIONS - MAIN SWITCH, LOCAL & DISTIBUTION BOARD • Mainswitchfunctionsasasourceofelectriccurrent and distributes itto other parts according to requirements • Functionstostoptheflowofelectricitycurrentinthe circuit • Distribution board comprises ofmain switch,circuit breaker and other switches.Itreceives electric currentexternallybefore distribution.

  15. ELECTRICAL INSTALLATIONS - CIRCUIT BREAKERS • Functionswhenthereis overloadof electricity • Prevents overloadof excess heat that may cause combustion • Closedswitch • Ithasanautomaticswitchwhichretractsfromthe ‘on’positionto ‘off’positionwhenthere is an overloadofelectricityflowin thecircuit

  16. ELECTRICAL INSTALLATIONS - FUSE • Apiece of thinmetalthatwill melt ata level belowoverloadleveltobreakthecircuit • Stopstheflow of electricity

  17. ELECTRICAL INSTALLATIONS - EXTERNAL SOCKET Entrytothecircuitandallowstappingtolet electricityflowtotheequipmentrequiringit.

  18. ELECTRICAL INSTALLATIONS - PLUG Isconnectedtoaflexiblecablethatsupplies electricitytotheequipment,andisinserted intotheexternalsockettocompleteanother circuit.

  19. ELECTRICAL HAZARDS • Electricshock • Lighting • Fire • Electrostatic

  20. ELECTRICAL HAZARDS - ELECTRIC SHOCK • Usuallyfromalivewiretoearth • Makesthemusclesshortenandspasm • Mayaffect heartreactions • Mayresultinrespiratoryfailure

  21. ELECTRICAL HAZARDS - LIGHTING • ArcEyes • Fromultravioletlightswhenlookingatelectricarc orweldingflash • Symptomssimilar toconjunctivitis • Situationmaycontinuefor3 to4 days • Doesnotaffectcontactlens 20

  22. ELECTRICAL HAZARDS - FIRE equipment charges. orrelease ofelectrostatic

  23. ELECTRICAL HAZARDS ELECTROSTATIC • Results thatis produced by electricity charges trappedinisolators.Thechargesmaybedistributed insideoroutsideobjectsthathavebeenisolatedor itmay concentrate on conductors thathave been earthed • Highvoltage,lowcurrent • Effectofelectric shock and ignition sources in a highlyflammableenvironment,if chargesare high

  24. ELECTRICAL SAFETY • Theeffectsofelectriccurrentdifferaccordingto: • Age • Gender • Bodyresistance • Healthlevel

  25. HOW ELECTRICITY FLOWS IN THE BODY Highpain Moderatepain Toearth Toearth HANDTOFEET HANDTOHAND 24 Copyright@NIOSH2005

  26. EFFECTS OF ELECTRICITY • Dependson: • Theamountof currentand voltage • Bodyresistance • Severityofelectricshock • Durationofcurrentflow

  27. OHM LAW Current(I):Volt(V) Resistance(R) Orusetheactualmeasurement: Amperes: Volt Ohm

  28. OHM LAW EXAMPLE Forelectricshockeffects valueofdanger 27

  29. EFFECTS OF ELECTRICITY NationalSafetyCouncil-Indus.Safety&Healthmgmtbook Current(mAmps) Effectstohuman 3 milliamps Mildshock 7milliamps Painfulelectric shock 20milliamps Difficultybreathing 70milliamps Riskof death 700milliamps Burningofbodytissues 3000milliamps Heartstops

  30. HUMAN BODY RESISTANCE TO ELECTRICITY FLOW TYPESOFRESISTANCE Dry humanskin Wethumanskin Internalbody -Handto feet Internalbody -Earto ear VALUE 100,000-600,000ohms Approx.1,000Ohm 400-800ohms Approx.100ohms

  31. VOLTAGE SHOCK THRESHOLD AT 50 Hz

  32. PRINCIPLES OF ELECTRICAL SAFETY Mainobjective: Protectpeoplefromelectricshock, fireandeffects of burnsduetocontactwithelectricity

  33. PRINCIPLES OF ELECTRICAL SAFETY • Twobasicpreventionsteps: • Protectionfromdirectcontact • Protectionfromindirectcontact

  34. PRINCIPLES OF ELECTRICAL SAFETY • Protectionfromdirectcontact • Providesisolationtoparts ofequipmentsthathas potentialto release charges • Protectionfromindirectcontact • Provideseffective earthingto isolatemetals that canchargeelectricityincaseoffailureofthe mainisolator

  35. SAFE USE OF ELECTRICITY • Considerations: • Circuitprotector • Isolatingswitch • Equipmentmaintenanceandrepair • Earthing • Protection

  36. SAFE USE OF ELECTRICITY CIRCUIT PROTECTOR • Allelectricequipmentsusedmusthavea fuseandcircuit breakerthat issuitable topreventitfrom overloading.

  37. SAFE USE OF ELECTRICITY - ISOLATING SWITCH • Labeled • Easyreachablefromthefloor • Is attachedtoeachindividualmachinery • Possesssafetylockwhenin‘off’ position

  38. SAFE USE OF ELECTRICITY EQUIPMENT MAINTENANCE & REPAIR • Preparesafeworkproceduresfor maintenanceworks • Preparerulesandconductinspection/ monitoring • Prepareamaintenanceprogramme/ schedule

  39. SAFE USE OF ELECTRICITY EQUIPMENT MAINTENANCE & REPAIR • Prepareaccessaroundtheequipmentto alloweasymaintenanceandrepair • Worksdonebyacompetenttechnician • Ensuresuitablereplacement of components such asfuse,capacitors

  40. SAFE USE OF ELECTRICITY - EARTHING • Forallelectrical items • Circuit isconnecteddirect,not througha switch

  41. SAFE USE OF ELECTRICITY - PROTECTION • Provideforearthleakageprotectionsuchas Residual CurrentDevices • Haveanemergencystopswitch,interlock switch • Isolatetheconductor • Displayappropriatewarningsignages

  42. ELECTRICAL SAFETY CONTROLS • Governmentcontrols: • Provisionof Regulationsandenforcement • ElectricitySupplyAct1990 • ElectricitySupplyRegulations1994 • SIRIM Standards • OccupationalSafetyandHealth Act1994(OSHA 1994)

  43. ELECTRICAL SAFETY CONTROLS • OCCUPATIONALSAFETYANDHEALTHACT1994 • Employers: • Havesafe systemofwork(SOP) • Providetraining,informationandinstruction • Providepreventionmeasures andprotectiontoworkers andcontractors

  44. ELECTRICAL SAFETY CONTROLS • OCCUPATIONALSAFETYANDHEALTHACT1994 • Manufacturers,suppliers,designers: • Conducttestingandinspectionto ensureuser safety • Workers: • Complytoall rules andregulationsissued bythe employer

  45. CONCLUSION • Electricitymayresultinmultiplehazardsthatmay affectworker safetyandhealth • Therearetwobasicpreventionmeasuresthatmay betaken toprotectagainstelectricalhazards • Thesearefollowedelectricalsafetymeasuresasdiscussed • Thegovernmentalsoregulatesthesafeuseofelectricity through the formulationandenforcement ofvariousregulations 44

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