1 Electrical Systems Module 2

1.1 DEFINITION OF ELECTRICITY a form of energy generated byfriction, induction or chemical change, having magnetic, chemical and radiant effect.the motion of free electrons througha solid conductor.1.2 SOURCES OF ELECTRICITY STORAGE BATTERIESGENERATORS1.GENERAL STORAGE BATTERIES are used to supply emergency lighting circuits for hallways, stairways, exits and to energize police and fire alarm systems and certain types of signal systems. GENERATORS for generating electric currentAlternating Current Generators or Alternators The bulk of electrical energy utilized today is in the form of alternating current, including energy for power and lighting. Direct Current Generators Thesefurnish electrical energy for elevators, escalators, intercommunicating telephone systems, control of signal systems, and clock systems. 1.3 OTHER DYNAMO ELECTRIC MACHINES MOTORS for converting electrical energy to mechanical energy. TRANSFORMERS for converting one voltage to another, from lower to higher or from higher to lower ROTARY CONVERTERS for changing alternating current to direct current and vice versa. 1.4 TYPES OF CURRENT ALTERNATINGCURRENTa currentwhichisperiodically varyingintimerateandin direction.Itrisesfromzeroto maximum,fallstozero,reverses itsdirectionandagainreturnsto zero.DIRECTCURRENTacurrent which flows at a constant time rate and in the same direction. UNIT OF QUANTITY1.5 UNITS OF ELECTRICITY COULOMBacoulombofelectricity comprisesapproximately6.25x1018 electrons. AMPEREAnampereofcurrent representsarateofflowofone coulombor6.25x1018 electrons/secondthroughagiven cross section. UNIT OF ELECTRIC POTENTIAL VOLTistheelectromotiveforce orpotentialdifferencebetweentwo pointsinanelectricfieldwhichwill moveachargeofonecoulomb between these points. UNIT OF RESISTANCE OHMTheresistancewhichwill allow one ampere of current to flow when one volt is impressed upon it. UNIT OF ELECTRIC POWER WATTtheunitofelectric powerortherateofdoing electrical work. UNIT OF ENERGY WATT-HOURStheunitof energyorthecapacityfordoing work. 1.6 OHMS LAW I (amp) = V (Volts) / R (Ohms) The current, I,that will flow in a d-c circuit is directly proportional to the voltage ,V, and inversely proportional to the resistance , R, of the circuit. is the effective utilization of available energy by reducing peak loads and lowering demand charge. The control devices and systems are referred to as load shedding control, peak demand control, peak load regulation, and power use control. LOADSCHEDULINGANDDUTY-CYCLECONTROLtheinstallations electric loads are analyzed andscheduled torestrictdemandbyshiftinglargeloads tooff-peak hours and controlled to avoid coincident operation. DEMANDMETERINGALARMin conjunctionwithadutycyclecontroller, demand is continuouslymetered andan alarmissetonwhenapredetermined demandlevel is exceeded. 1.7 ELECTRIC LOAD CONTROL AUTOMATICINSTANTANEOUS DEMANDCONTROLalsocalledrate control,itisanautomatedversionofthe demandmeteringalarmsystem,whereit automatically disconnects or reconnects loads as required. IDEALCURVECONTROLThiscontroller operatesbycomparingtheactualrateof energyusagetotheidealrate,andcontrols KWdemandbycontrollingthetotalenergy used within a metering interval. FORECASTINGSYSTEMSare computerizedsystemswhichcontinuously forecasttheamountofenergyremainingin the demand interval, then examine the status andpriorityofeachoftheconnectedloads and decide on the proper course of action. WATTMETER VOLTAGE LEADS LOAD WM CURRENT LEADS POWER SOURCE 1.8 MEASURING ELECTRIC CONSUMPTION KWH METERS To measure energy, the factor of time is introduced, such that; energy = power x time.A-C electric meters are basically small motors, whose speed is proportional to the power being used. The number of rotations is counted on the dials which are calibrated directly in kilowatt-hours. 2. BUILDING ELECTRICAL SYSTEMS2.1 BRANCH CIRCUITSAn electrical circuit may be defined as a complete conducting path carrying current from a source of electricity to and through some electrical device or load and back to the source. The two wire circuit, which is the most elementary of all wiring systems, consists of a live wire carrying the current to the various power consuming devices in the circuit and a neutral or grounded wire which is the return wire carrying the circuit back to the source of supply. SERIES CIRCUITPARALLEL CIRCUITSERIES CIRCUIT is one in which the componentsareconnectedintandem.All separateloadsofthecircuitcarrythe sameequalcurrentandthetotal resistance,R,isthesumofthe resistances around the circuit. PARALLELCIRCUIT(orMultiple Circuit)isoneinwhichthe componentsorloadsaresoarranged thatthecurrentdividesbetweenthem. Eachoutlethasalivewireconnectedto thecurrentcarryingwireofthecircuit and also a neutral wire or grounded wire connectedtothereturnwireofthe circuit. With this system, the total current flowingthroughthecircuitisthesumof the current flowing through each outlet. R=R1+R2+R3+R4+R5 10 amp R 1R 2 10 amp ELEC SOURCE CIRCUIT IN SERIES R 5 R 4 10 amp 10 amp R 3 ELECTRICAL SOURCE CIRCUIT IN PARALLEL 3 amp 1 amp 1 amp1 amp + R 1R 2R 3 1 R =1/R1+1/R2+1/R3 CLASSIFICATIONS OF BRANCH CIRCUITSGeneralPurposeBranchCircuit-suppliesoutletsforlightingand appliances,includingconvenience receptacles. ApplianceBranchCircuit-supplies outletsintendedforfeedingappliances. Fixed lighting is not supplied. IndividualBranchCircuit-is designed to supply a single specific item, suchasamotorloadoraunitair-conditioner. SIZE REQUIRED FOR ITEM FED 15, 20, 30, or 50A AA LTGA GENERALLY 15, 20A SINGLE ITEM Branch Circuit The portion of an electrical system extending from the final overcurrent device protecting a circuit to the outlets served by the circuit Distribution Panel A panel for distributing power to other panels or to motors and other heavy power-consuming loads.Controls, distributes and protects a number of similar branch circuits in an electrical system Low-Voltage Of or pertaining to a circuit in which alternating current below 50 volts is supplied by a step-down transformer form the normal line voltage used in residential systems to control doorbells, intercoms, heating and cooling systems and remote lighting fixtures.Low-voltage circuits do not require a protective raceway General Purpose Circuit A branch circuit that supplies current in a number of outlets for lighting and appliances Appliance Circuit A branch circuit that supplies current in one or more outlets specifically intended for appliances Individual Circuit A branch circuit that supplies current only to a single piece of electrical equipment GENERAL CIRCUITING GUIDELINES1. General:Branchcircuitsshallbe sufficienttosupplyaloadof30 watts per square meter (3 watts per squarefoot)inbuildingsexcluding porches, garages and basements. 2.Inallbutthesmallestinstallations, connectlighting,convenience receptacles,andappliancesin separate circuits. The Code requires a minimumof2-20amperes appliancebranchcircuittofeedall small appliance outlets in the kitchen, pantry, dining and family room. DINE KIT Ref C2 Range C1 C4 C3 C3 C3 20 amp 20 amp 3.Conveniencereceptaclesinanarea shallbewiredtoatleasttwo differentcircuitssothatincaseof failure in any one of the circuits, the entireareawillnotbedeprivedof power. 4.Generalpurposebranchcircuitsshall beratedat20ampereswiredwith No.12AWGminimum.Switchlegs maybeNo.14AWGifthelighting load permits. 5.Limitthecircuitloadforlightingand smallapplianceson15ampand20 ampcircuitloadsandon15and20 amp overcurrent devices respectively. 2.2 SINGLE PHASE ELECTRICAL SYSTEMSTwo-Wire Single Phase DC or ACThree-WireSinglePhaseDC (EDISON SYSTEM) Three-Wire Single Phase ACFor homes and small commercial buildings SWITCH FUSE 220 V 110 V 110 V A single phase electrical system can either be 2-wire or 3-wire and composes two hot legs and a neutral wire.2.2 THREE PHASE ELECTRICAL SYSTEMSThree-Wire Three Phase AC Four-Wire Three-Phase ACFor industries and large commercial buildings A-B 220V B-C 220V A-C 220V ABC A B C 220V NBCA 220V 220V 110V 110V 110V MOTOR The Three Phase AC electricity is a Triple Circuit. The lighting and outlet loads are connected between any phase leg and a neutral line. While machineries and other bigger loads are connected to the phase leg only.2.3 COMPONENTS OF THE BUILDING ELECTRICAL SYSTEMSubstation An auxiliary power station where electrical current is converted or where voltage is stepped up or down Service The supplying of utilities required or demanded by the public Line Drop The decrease in voltage between two points on a power line, usually caused by resistance or leakage along the line Service Entrance Conductor The portion of a service conductor extending from a service drop or service lateral to the service equipment of a building Watt-Hour Meter A meter for measuring and recording the quantity of electric power consumed with respect to time Transformer Vault A fire-rated room housing a transformer and auxiliary equipment for a large building Switchgear Room Contains the service equipment for a large building Service Equipment Equipment necessary for controlling, metering and protecting the electric power supply to a builidng Standby Generator For providing emergency power during a power outage. Uninterruptible Power Supply An emergency system designed to provide pwer automatically and instantaneously Switchboard One or a group of panels on which are mounted switches, overcurrent devices, metering instruments and buses Unit Substation A freestanding enclosure housing a disconnect switch, a step-down transformer and switchgear Feeder Any of the conductors extending from the service equipment to various distribution points in a building Service Drop The overhead portion of service conductors extending from the nearest utility pole to a building Service Lateral The underground portion of service conductors extending from a main power line or transformer to a building Lightning Rod Any of several conducting rods installed at the top of a structure and grounded to divert lightning away from the structure.Also called air terminal Lightning Arrester A device for protecting electric equipment from damage by lightning or other high-voltage currents, using spark gaps to carry the current to the ground without passing through the device Spark Gap A space between two terminals or electrodes across which a discharge of electricity may pass at a prescribed voltage Servcie Drop The overhead portion of service conductors extending from the nearest utility pole to a building Servcie Lateral The underground portion of service conductors extending from a main power line or transformer to a building Service Conductors extend from a main power line or transformer to the service equipment of a building Servcie Entrance Conductor The portion of a service conductor extending from a service drop or service lateral to the service equipment of a building Watt-Hour Meter Measures and records the quantity of electric power consumed with respect to time.Supplied by the public utility, it is always placed ahead of the main disconnect switch so that it cannot be disconnected For multiple-occupancy buildings, banks of meters are installed so that each unit can be metered independently Grounding Rod or Electrode Is firmly embedded in the earth to establish a ground connection To panelboards Direct burial cable may be used for residential service connections A transformer is used by medium-sized and large buildings to step down from a high supply voltage to the service voltage.To reduce costs, maintenance and noise and heat problems, a transformer may be placed on an outdoor pad.If located within a building, oil-filled transformers require a well-ventilated, fire-rated vault with two exits and located on an exterior wall adjacent to the switchgear room.Dry-type transformers used in small- and medium-sized buildings may be replaced together with a disconnect switch and switchgear in a unit substation The service switch is the main disconnect for the entire electrical system of a building, except for any emergency power systems. The service equipment includes a main disconnect switch and secondary switches, fuses and circuit breakers for controlling and protecting the electric power supply to a building.It is located in a switchgear room near the entrance of the service conductors The main switchboard is a panel on which are mounted switches, overcurrent devices, metering instruments and busbars for controlling, distributing and protecting a number of electric circuits SERVICE ENTRANCE the point of delivery of electricity to a building by a public utility company. MAIN SWITCHBOARD The service entrance conductors in the form of bus bars terminates in the main switchboard and connects to the distribution panel boards by means of feeder circuits protected by circuit breakers. The main switchboard serves for the control, protection and metering of the main feeders. FEEDER CIRCUITS A feeder circuit isasetofconductorswhichextends fromthemainswitchboardtoa distributing center (panel board) with no othercircuitsconnectedtoitbetween the source and the distributing center. SUB-FEEDERCIRCUITSareline extensionsofafeeder,fedthrougha panelboardorcut-out,orfromone distributing center to another and having noothercircuitconnectedtoitbetween the two distributing centers. A sub-feeder serves to distribute power from the main feederstosmallerlocalpanelboards, called sub-panel boards.PANEL BOARDS AND SUB-PANEL BOARDS (also called CUT-OUTS) These serve to control and protect the sub feeders and branch circuits. UTILIZATIONEQUIPMENTThese arethelighting,powerandmotorloads andwiringdeviceswhicharedirectly handled and utilized by users. BRANCHCIRCUITSTheseare smallcapacityconductorswhichdeliver energy to lamps, motors and other loads within the circuit. Service Switch The main disconnect for the entire electrical system of a building except for any emergency power systems Panel A board on which are mounted the switches, fuses and circuit breakers for controlling and protecting a number of similar branch circuits installed in a cabinet and accessible from the front only.Also called a panelboard. Bus A heavy conductor, usually in the form of a solid copper bar, used for collecting, carrying and distributing large electric currents.Also called a busbar Grounded Conductor Any conductor of an electrical system intentionally connected to a ground connection Grounding Electrode A conductor, as a metal ground rod, ground plate or cold-water pipe, firmly embedded in the earth to establish a gorund connection Fuse A device containing a strip or wire of fusible metal that melts under the heat produced by excess current thereby interrupting the circuit Circuit Breaker A switch that automatically interrupts an electric circuit to prevent excess current from damaging apparatus in the circuit or from causing a fire.A circuit breaker may be reclosed and reused without replacement of any components.Also called a breaker. Ground Wire A conductor connecting electric equipment or a circuit to a ground connection.Also called a grounding conductor 2.4 ILLUSTRATING THE COMPONENTS OF THE BUILDING ELECTRICAL SYSTEMBLOCK DIAGRAM A horizontal single line diagram of the buildings electrical system from the incoming service to the utilization items at the end of the system where the major electrical components are shown as blocks or rectangles. RISER DIAGRAM Is a vertical line diagram of the major electrical components of the buildings electrical system presented showing the spatial relations between components.ELEVATORS PP MR MACHINE ROOM 5A LP 4A 3A 2A 1ALP LOBBY 1B 2B 3B 4B 5B LEFT RISER 5C 4C 3C 2C 1C ROOF CENTRAL RISER SHAFT RIGHT RISER M.C.C. MACHINE ROOM FA LPSE FIRE ALARM PANEL STAIR AND EXIT PANEL MMETERING SPARE 2.5 EMERGENCY ELECTRIC SUPPLY SYSTEM EmergencySystemsprovideelectric powerandilluminationessentiallyforlife safetyandprotectionofpropertyduring an emergency, such as, electricity for exit lighting,elevators,firealarmsystems, fire pumps and the like. StandbySystemsprovidepowerto selectedloadsnotdirectlyinvolvedwith lifesafety,suchas,waterandsewage treatmentplantsandindustrialmachines for manufacturing processes. EMERGENCY POWER EQUIPMENT BatteryEquipmentCentralstorage batteriesaremountedinindividualracks andalwaysprovidedwithautomatic charging equipment. Engine-GeneratorSetsaremachines intendedtoproduceelectricityand composedofthreecomponents:the machineanditshousing(ifany),fuel storage tank and the exhaust facilities. EMERGENCYWIRINGSYSTEMS USING THE BATTERY Small emergency appliance connected direct to a storage batteryGroupsofemergencyloads connectedtocentralstoragebattery through automatic device Emergencyequipmentloadsare entirelyseparatefromnormalloads andaregenerallyde-energized.The contactorisactivatedwhenitsenses power loss.EMERGENCYWIRINGSYSTEMS USING THE GENERATOR Emergencysystemhandledbya singletransferswitchwhich automaticallyturnsonwhenitsenses power loss at its downstream location. Emergencysystemhandledby multiple switches Emergencyservicetotallyseparated from normal through its own emergency serviceentrance,comingfromdifferent transformers or feeders. Sameasabove,butbothservice entrancessupplynormalloadsand each act as standby for each other. arematerialswhichallowthefree flow of electrons through them. Wiresaresingleinsulated conductors No. 8 AWG (American Wire Gaugeorsmaller;fortheEnglish System,itistheB&SGaugeor BrowneandSharpeGauge.The smallestsizeofwirepermittedisNo. 14. Cablesaresingleinsulated conductorsNo.6AWGorlarger;or theymaybeseveralconductorsof any size assembled into a single unit. BusBarslargeconductorswhich arenotcircularincrosssectionand usually found only to supply the main switch boards. 3. ELECTRICAL MATERIALS AND EQUIPMENT 3.1 CONDUCTORS CONDUCTORSIZES AWG/MCMSTANDARD All conductor sizes from No. 16toNo. 0000 (also designated 4/0) are expressed in AWG. Beyond AWG No. 4/0, a different designation, MCM (or thousand circular mil) is used. In this designation, the smallest MCM size is 250 MCM or and the biggest is 500 MCM.A circular MIL is an artificial area measurement, representing the square of the cable diameter (diam2) when the diameter is expressed in mils (thousands of an inch). Thus a solid conductor inch in diameter is 500 mils in diameter, or 250,000 circular mils in area, (500)2or 250 MCM; thus; CM/1000 =diam2= (500)2/1000 = 250,000/1000=250 MCM In the metric system, conductor sizes are given simply as the diameter in millimeters (mm). CONDUCTOR AMPACITY Conductorcurrentcarryingcapacityor ampacityisthemaximumoperating temperature that its insulation can stand continuously.Heatisgeneratedasa resultofthecurrentflowingandthe conductorresistance.Whenconductors areplacedinanenclosedconduit,the heatgeneratedisnotaseasily dissipated as it would be if the conductor werefreeintheair.Thus,thecurrent rating of a conductor in free air is much higher than that for the same wereit in a conduit. TYPES OF CABLES Armored Cable (Type AC) a fabricated assemblyofinsulatedconductors enclosed in flexible metal sheath. Metal Clad Cable (Type MC) a factory assembledcableofoneormore conductorseachindividuallyinsulated andenclosedinametallicsheathof interlockingtapeofasmoothor corrugated tube. MineralInsulatedCable(TypeMI)a factoryassembledconductor/sinsulated withahighlycompressedrefractory mineral insulation enclosed in a liquid and gas tight continuous copper sheath. Non-Metallic Sheathed Cable (Type NM orNMC)alsoknownbythetrade nameROMEX,isafactoryassemblyof two or more insulated conductors having amoistureresistant,flameretardant, and non-metallic material outer sheath.ShieldedNon-MetallicSheathedCable (Type SNM) a factory assembly of two ormoreinsulatedconductorsinan extrudedcoreofmoistureresistantand flameretardantmaterialcoveredwithin an overlapping spiral metal tape. UndergroundFeederandBranchCircuit Cable(TypeUF)amoistureresistant cableusedforundergroundconnections includingdirectburialinthegroundas feeder or branch circuit. ServiceEntranceCable(TypeSEor USE)asingleormulti-conductor assemblyprovidedwithorwithoutan overall covering primarily used for service wire. Power and Control Tray Cable (Type TC) a factoryassembledtwoormoreinsulated conductorswithorwithoutassociatedbare or covered grounding under a metallic sheath andisusedforinstallationincabletrays, raceways, or where supported by wire. FlatCableAssemblies(TypeFC)an assemblyofparallelconductorsformed integrally with an insulating material web designed specially for field installation in square structural channels. FlatConductorCable(TypeFCC) consistsofthreeormoreflatcopper conductorsplacededgetoedge separatedandenclosedwithina insulatingassembly.Thistypeofcable isusedforapplianceorindividual branchcircuitsinstalledinsidefloor surfaces.MediumVoltageCable(MV)a single or multi-conductor solid dielectric insulatedcableratedat2,000to 35,000volts.TradenameisMedium Voltage Solid Dielectric. 3.2 INSULATORS INSULATORS are materials which prevent the flow of electrons through them. General Wiring Trade nameType Letter Maximum Operating Temperature Application Provisions Moisture-& heat-resistant rubber RHW75O C 167O F Dry and wet Locations ThermoplasticT60O C 140O F Dry locations Moisture-resistant thermoplastic TW60O C 140O F Dry and wet Locations Heat-resistant thermoplastic THHN90O C 194O F Dry locations Moisture-& heat-resistant thermoplastic THW75O C 167O F Dry and wet Locations Moisture-& heat-resistant thermoplastic THWN75O C 167O F Dry and wet Locations Moisture-& heat resistant cross-linked thermosetting polyethelene XHHW90O C 194O F 75O C 167O C Dry locations Wet locations Silicone-asbestosSA90O C 194O F Dry locations Asbestos and Varnished Cambric AVA110O C 230O F Drylocations only TYPES OF INSULATORS CONDUITSarecircularracewaysused toenclosewiresandcablesandareof metal or plastic (PVC). 3.3 CONDUITS Toprotecttheenclosedconductors frommechanicalinjuryandchemical damage. Toprotectpeoplefromshockhazards by providing a grounded enclosure. To provide a system ground path. To protect the surroundings against fire hazard as a result of overheating or short circuiting of the enclosed conductors. To support the conductors. TYPES OF STEEL CONDUITS Heavy-wall steel conduits called Rigid Steel Conduits or RSC with an approximate thickness of 0.117 mm. Intermediate Metal Conduit or IMC with thickness of 0.071 mm. Thin-wall steel conduits named Electric Metal Tubing or EMT. RSCs and IMCs use the same fitting, called condulets, and are threaded alike at the joints.EMTs are not threaded but use set screw and pressure fitting and are not recommended for embedding in concrete nor permitted in hazardous areas. IMCs yield a larger inside diameter (ID) for easier wire pulling and is lighter than the RSC. Standard length of steel conduits is 3 M or 10 ft. 3.4RACEWAYSarechannelsor wiringaccessoriessodesignedfor holdingwires,cablesandbusbarsthat are either made of metal, plastic, or any insulating medium. 3.5 OUTLETS and RECEPTACLES An outlet is a point in the wiring system at which current is taken to supply utilization equipment. It refers only to the box. A receptacle is the wiring device in which the utilization equipment (appliance) cord is plugged into. ConvenienceOutletorAttachment Cap-thecompleteset-upwhich establishesconnectionbetweenthe conductoroftheflexiblecordandthe conductorsconnectedpermanentlyto the receptacle. Lighting Outlet is an outlet intended fordirectconnectiontoalampholder, lightingfixture,orpendantcord terminating in a lamp holder. ReceptacleOutlet is an outlet where one or more receptacles are installed. 3.6 SWITCHES are devices for making, breaking,orchangingconditionsinan electricalcircuitundertheconditionsof load whichthey are rated. TYPE OF SWITCH ACCORDING TO VOLTAGE Switches are rated as250V, 600V,or 5KV as required. TYPE OF SWITCH ACCORDING TO INTENSITY OF USE 1. Normal Duty (ND) intended for normal use in light and power circuits as in general-purpose switches. 2. Heavy Duty (HD) intended for frequent interrupting. 3. Light Duty (LD) intended to connect the loads occasionally, such as service switches. TYPE OF SWITCH - ACCORDING TO TYPE OF SERVICE 1. Service Switch intended to disconnect all the electric service in the building except emergency equipment. This may comprise one to six properly rated switches that are assembled into a switchboard. 2. Power Switches a) General purpose switches are intended for use in general distribution and branch circuits. b)Disconnecting or isolating switches are intended for disconnecting or isolating circuits;used for circuits rated at more than 600 volts. a) Generalpurpose switches are single-pole or double-pole switches for the general purpose use of connecting or cutting-off circuits for the control of lamps or other loads from a single point. b) Three-way switches are used where it is desired to control lamps from two different points, as in a stairwell. c) Four-way switches are used in conjunction with two 3-wire switches where it is desired to control lamps from three or more desired points. 3. Wiring Switches include all the relatively small switches that are employed in interior wiring installations for the control of branch circuits, individual lamps or appliances. d) Electrolier or multi-circuit switches are used for the control of lights in multi-lamp fixtures so that one lamp or set of lamps may be turned on alone or in combination with other lamps. e) Momentary contact switches are used where it is desired to connect or cut-off a circuit for only a short duration. The switch is provided with a spring so that it will return to its original position as soon as the handle or button is released. f) Dimmer switches a rheostat[1] or similar device for regulating the intensity of an electric light without appreciably affecting spatial distribution. Also called a dimmer. Wiring switches may either be the flush type, surface type or the pendant type. TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM Wiring switches may also be classified according to the operating mechanism as: 1.Rotary switch 2.Push-button switch 3. Toggle or tumbler switch TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS 1. Poles that part of the switch which is used for making or breaking of a connection and which is electrically insulated from other contact making or breaking parts. 2. Throws - a single throw switch is one which will make a closed circuit only when the switch is thrown in one position. A double throw switch will make a closed circuit when thrown in either of two positions. SPECIAL SWITCHES 1. Time Controlled Switches This device comprises a precision low speed miniature drive motor (timer) to which some type of electric contact-making device is connected. 2. Remote Control (RC) Switches A contactor[1], or more specifically, a relay[2], that latches after being operated wireless from a distance. 3.Air Switch a switch in which the interruption of a circuit occurs in air. 4. Knife Switch a form of air switch in which a hinged copper blade is placed between two contact clips. 5. Float Switch a switch controlled by a conductor floating in a liquid. 6. Mercury Switch an especially quiet switch that opens and closes an electric circuit by shifting a sealed glass tube of mercury so as to uncover or cover the contacts. 7. Key Switch a switch operated only by inserting a key or a card. Also called a card switch. 8. Automatic Transfer Switch (ATS) This device, an essential part of an emergency or standby service, is basically a double throw switch, generally 3-pole, so arranged that on failure of normal power, emergency service is automatically supplied. 3.7 WALL PLATES OR FACEPLATES - These are coverings for switches and wall outlets usually made of metal or of phenollic compound (Bakelite). 3.8OVER-CURRENTCIRCUIT PROTECTIVEDEVICESaredevices whosesolepurposeistoprotect insulation,wiring,switchesandother apparatusfromoverheatingorburning, duetooverloads,tofaultsortoshort circuits,byautomaticallycuttingoffthe circuit. FUSE is a device consisting of an alloy link of wire with a low melting temperature which is inserted in the circuit, in such a way, that all current which passes through the circuit, must also pass through this metal.CIRCUIT BREAKERS is an over-current protective device designed to function as a switch, or it can be manually tripped and thus act as a circuit switch. It breaks a circuit with an automatic tripping device without injury to itself. GROUNDFAULTCIRCUIT INTERRUPTERS(GFCIorGFI)is anovercurrentprotectivedevicethat willprovidegroundfaultprotectionas wellasfunctionasanordinarycircuit breaker. PANELBOARDSpopularlyknownas panelorelectricalpanel,itissimply the box wherein the protective devises are housedfromwhichthecircuitsandbus bars terminate. SWITCHBOARDSarefreestanding assembliesofswitches,fuses,and/or circuitbreakerswhosefunctionnormally istoprovideswitchingandfeeder protectiontoanumberofcircuits connected to a main source.UNITSUBSTATIONS(TransferLoad Centers)anassemblyofprimaryswitch-fuse-breaker,step-downtransformer, meters,controls,busbarsandsecondary switchboard.Itisusedtosupplypower fromaprimaryvoltagelinetoanylarge facility. 4.1 WIRING METHODS KNOBANDTUBEWIRINGan obsoletewiringsystemconsistingof singleinsulatedconductorssecuredto andsupportedonporcelainknobsand tubes.Whenwiresrunthroughwalls, they are inserted into a nonmetallic fire-resistant tubing called a loom. RIGID METAL CONDUIT WIRING is the best and most expensive among the usual type of wiring. Its advantages are: 1. it is fireproof; 2.moisture proof; 3.it is mechanically strong so that nails cannot be driven through it and it is not readily deformed by blows; 4. it resists the normal action of cement when embedded in concrete or masonry. 4.WIRING SYSTEMS FLEXIBLEMETALCONDUIT WIRINGItsinstallationismuch easierandquickerthanthatofrigid metalconduits.Unliketherigidconduits which come in short lengths of 10 ft.(3 M),flexiblemetalconduitwiringcomes in length of 25 ft 250 ft (8 M 83 M) depending on the size of the conduit. ARMOREDCABLEWIRING(BX WIRING)consistsofrubberor thermoplasticcoveredwireprotected frominjurytoacertainextentfrom dampness by one or two layers of flexible steel armor. SURFACEMETALRACEWAY WIRING the wires are supported on a thinsheetsteelcasing.Theracewayis installedexposed,beingmountedonthe wallsorceiling.Metalracewaysmustbe continuousfromoutlettooutletor junctionbox,designedespeciallyforuse with metal raceways. FLAT CABLE ASSEMBLIES a field installed rigidly mounted square structural channel (1 5/8 standard) designed to carry 2 to 4 conductors (No. 10 AWG) and will act as light duty (branch circuit) plug-in busways. LIGHTINGTRACKafactory-assembledchannelwithconductorsfor onetofourcircuitspermanently installedinthetrackthatwillactas lightduty(branchcircuit)plug-in busways. CABLETRAY/OPENRACEWAY isacontinuousopensupportfor approvedcables.Whenusedasa generalwiringsystem,thecables mustbeself-protected,jacketed types, type TC. FLOOR RACEWAYS The NEC recognizes three types of floor raceways: 1. Underfloor Ducts (UF) installed beneath or flush with the floor. These underfloor ducts usually requires a triple duct systemfor power,telephone and signal cabling. 2. Cellular Metal Floor Raceway Found usually in office landscaping, it is an integrated structural/electrical system in a cellular metal floor. 3.Precast Cellular Concrete made of concrete cells fed from header ducts, which are normally installed in concrete fill above the hollow core structural slab or fed from the ceiling void below. The cells can be used for air distribution and for piping. CEILINGRACEWAYSYSTEMS under-the-ceilingracewayscomposedof headerductsanddistributionducts separateforpowerandtelephonecabling. Theypermitveryrapidchangesinlayouts atlowcostandarethereforeparticularly desirableinstoreswherefrequentdisplay transformationsnecessitatecorresponding electrical facility adjustments. PRE-WIRED CEILING DISTRIBUTION SYSTEMSareceilingracewaysthatare pre-wiredinthefactoryandpluggedin where required. FEEDER BRANCH CIRCUIT-CEILING/WALL BRANCH CIRCUIT-FLOOR 3&4 WIRES CIRCUIT NO. MARK INDICATES 2 WIRESCROSSING WIRES CONNECTING WIRES LIGHTING OUTLET CEILING RECESSED CEILING OUTLET DASH INDICATES SHAPE OF FIXTURE LIGHTING OUTLET WALL FLUORESCENT LAMP L LAMP HOLDER PSLAMP HOLDER WITH PULL SWITCH C D CLOCK OUTLET DROP CORD OUTLET FFAN OUTLET RRADIO OUTLET FLOOR OUTLET CONVENIENCE OUTLET SPLIT-WIRED DUPLEX CONVENIENCE OUTLET WEATHER PROOF OUTLET WP S OUTLET AND SWITCH R RANGE OUTLET SPECIAL PURPOSE OUTLET ref REFRIGERATOR OUTLET PUSH BUTTON BELL BUZZER CHIME CH ANNUNCIATOR LIGHTING PANEL POWER PANEL FUSE WH WATT-HOUR METER T TRANSFORMER J JUNCTION BOX GROUND ELECTRICAL SYMBOLS LIGHTING LAYOUT PLAN POWER LAYOUT PLAN ELECTRICAL REGULATIONS BY PD 1096 1. General Locational Requirements in Towns, Subdivisions, Human Settlements, Industrial Estates and the like. Overhead transmission and/or distribution lines/systems including transformers, poles, towers and the like shall be located and installed following the latest standards of design, construction and maintenance but so as not to cause visual pollution and in the interest of public safety,convenience,good viewing and aesthetics, these may be located along alleys or back streets. 2. Location of Poles and Clearances of Power Lines along Public Roads. 2.1 All poles erected on public roads shall be covered by Approved Pole Location (APL) plan from the Municipal Engineer. 2.2 Poles and transformer supports shall be located not more than 500mm inside from the road right-of-way or property line, and shall not obstruct the sidewalk, pedestrian path and/or the road drainage canal or structure, existing or proposed. 500 mm Property line Pole 2.3 Primary lines shall have a minimum vertical clearance of 10 m from the crown of the pavement when crossing the highway and 7.5 m from the top of the shoulder or sidewalk when installed along the side of the highway or street in a highly urbanized area. 10 m 7.5 m 2.4 Secondary, neutral and service lines shall have a minimum vertical clearance of 7.5 m from the crown of the road pavement when crossing the highway and from the top of the shoulder or sidewalk when installed along the side of the highway or street in highly urbanized area. 2.5 Clearances of Supporting Structures such as Poles, Towers and others and their guys and braces measured from the nearest parts of the objects concerned: A.From Fire Hydrants, not less than 5 m. B.From the Street Corners, where hydrants arelocated at street corners, poles and towers shallnot be set so far from the corners as to makenecessary the use of flying taps which areinaccessible from the poles. C.From Curbs, not less than 150 mm measured from the curb away from the roadway. 5 m 150 mm 3. Attachments on and Clearances from Buildings 3.1 Attachments for support of power lines and cables, transformers and other equipment and/or communications lines installed on buildings shall be covered by an Approved Attachment Plan from the local Building Official. 3.2 Where buildings exceed 15 m in height, overhead lines shall be arranged where practicable so that a clear space or zone at least 2 m wide will be left, either adjacent to the building or beginning not over 2.5 m from the building, to facilitate the raising of ladders where necessaryfor fire fighting. 2 - 2.5 m Pole 15 m 4. Open Supply Conductors Attached to Buildings Where the permanent attachment of open supply conductors of any class to buildings is necessary for an entrance such conductors shall meet the following requirements: 4.1 Conductors of more than 300 volts to ground shall not be carried along or near the surface of the buildings unless they are guarded or made inaccessible. 4.2 To promote safety to the general public and to employees not authorized to approach conductors and other current-carrying parts of electric supply lines, such parts shall be arranged so as to provide adequate clearance from the ground or other space generally accessible, or shall be provided with guards so as to isolate them effectively from accidental contact by such persons. 4.3 Undergrounded metal-sheathed service cables, service conduits, metal fixtures and similar noncurrent-carrying parts, if located in urban districts and where liable to become charged to more than 300 volts to ground, shall be isolated or guarded so as not to be exposed to accidental contact by unauthorized persons.As an alternative to isolation or guarding, noncurrent-carrying parts shall be solidly or effectively grounded. 4.4 Clearance of wires from building surface shall be not less than those required Table II. 4.5 Supports over buildings.Service-drop conductors passing over a roof shall be securely supported by substantial structures. Where practicable, such supports shall be independent of the building. Voltage of Supply Conductors Horizontal Clearance in Meters Vertical Clearance in Meters 300 to 8,700 volts1.02.5 8,700 to 15,000 volts 2.52.5 15,000 to 50,000 volts 3.03.0 > 50,000 volts3.0 + 10 mm per Kv in excess 3.0 + 10 mm per Kv in excess 5. Conductors Passing By or Over Buildings 5.1 Minimum Clearances.Unguarded or accessible supply conductors carrying voltages in excess of 300 volts may be run either beside or over buildings.The vertical or horizontal clearance to any building or its attachments (balconies, platforms, etc.) shall be as listed below.The horizontal clearance governs above the roof level to the point where the diagonal equals the vertical clearance requirement.This rule should not be interpreted as restricting the installation of a trolley contact conductor over the approximate center line of the track it serves. 5.2 Guarding of SupplyConductors/Supply of Conductors of 300 volts or moreshall be properly guarded by grounded conduit, barriers, or otherwise, under the following conditions: 1.Where the clearances set forth in Table II above cannot be obtained. 2.Where such supply conductors are placed near enough to windows, verandas, fire escapes, or other ordinarily accessible places within the reach of persons. 5.3 Where the required clearances cannot be obtained, supply conductors shall be of Grounded Metallic Shield, Jacketed Primary Cables grouped or bundled and supported by grounded messenger wires. V- V Clearance of line conductors from- Communication LInesSupply LInes In generalOn jointly used poles In general (0 to 8700 volts) On jointly used poles (0 to 8700 volts) Exceeding 8700 volts, add for each 1000 volts of excess Vertical and lateral conductors of the same circuit 75 mm75 mm75 mm75 mm6.25 mm Vertical and lateral conductors of other circuits 75 mm75 mm150mm150 mm10 mm Span and guy wires attached to same pole: general 75 mm150 mm150 mm150 mm10 mm Span and guy wires attached to same pole: when parallel to line 75 mm150 mm300 mm300 mm10 mm Lightning protection wires parallel to line: surfaces of cross arms 75 mm75 mm75 mm75 mm5 mm Lightning protection wires parallel to line: surfaces of poles 75 mm125 mm75 mm125 mm5 mm 6. Clearance of Service Drops 6.1 Service drop conductors shall not be readily accessible and when not in excess of 600 volts, shall conform to the following: a. Clearances over roof.Conductors shall have a clearance of not less than 2.5m from the highest point of roofs over which they pass with the following exceptions: 2.5 m Highest point Service Drop Conductor < 600 volts Exception No. 1.Where the voltage between conductors does not exceed 300 volts and the roof has a slope of not less than 100mm in 300mm, the clearance may not be less than 1m. 1 m Highest point Service Drop Conductor 300 volts Slope 1:3 Exception No. 2.Service drop conductors of 300 volts or less which do not pass over other than a maximum of 1.2m of the overhang portion of the roof for the purpose of terminating at a through-the-roof service raceway or approved support may be maintained at a minimum of 500mm from any portion of the roof over which they pass. 1.2 m Highest point Service Drop Conductor 300 volts 500mm 6.2 Clearance from the Ground.Conductors shall have a clearance of not less than 3m from the ground or from any platform or projection from which they might be reached. conductor platform 3 m 6.3 Clearance from Building Openings.Conductors shall have a horizontal clearance of not less than 1m from windows, doors, porches, fire escapes, or similar locations and shall be run at least 500mm above the top level of a window or opening. window 500mm 1 m 6.4 Service Drop of communication lines, when crossing a street, shall have a clearance of not less than 5.5 m from the crown of the street or sidewalk over which it passes. 5.50 m5.50 m Service drop of communication line ServiceDropofcommunicationlinesshallhaveaminimumclearanceof3m above ground at its point of attachment to the building or pedestal. 3m protector 3m 6.5 No parts of swimming and wading pools shall be placed under existing service drop conductors or any other over-head wiring; nor shall such wiring be installed above the following: a. Swimming and wading pools and the area extending 3m outward horizontally from the inside of the walls of the pool. b. Diving Structures c. Observation stands, towers or platforms Swimming pool Service drop conductor 3 m 7. Wiring Methods Service entrance conductors extending along the exterior or entering buildings or other structures shall be installed in rigid steel conduit or asbestos cement conduit or concrete encased plastic conduit from point of service drop to meter socket and from meter socket to the disconnecting equipment.However, where the service entrance conductors are protected by approved fuses or breakers at their outer ends (immediately after the service drop or lateral) they may be installed in any of the recognized wiring methods. 7.1 Abandoned Lines and/or portions of lines no longer required to provide shall be removed. 7.2 Power or communication poles, lines, service drops and other line equipment shall be free from any attachment for antennas, signs, streamers and the like. 7.3 Metallic sheaths or jackets of overhead power or communication cables shall be grounded at a point as close as possible to ground level whenever such cables change from overhead to underground installations. 8. Transformers 8.1 Oil-insulated Transformers Installed Outdoors.Combustible material, combustible buildings and parts of buildings, fire escapes, door and window openings shall be safeguarded from fires originating in oil- insulated transformers installed on, attached to, or adjacent to a building or combustible material.Space separations, fire-resistant barriers and enclosures which confine the oil of a ruptured transformer tank are recognized safeguards.One or more of these safeguards shall be applied according to the degree of hazard involved in cases where the transformer installation presents a fire hazard.Oil enclosures may consist of fire- resistant dikes, curbed areas or basins, or trenches filled with coarse, crushed stone.Oil enclosures shall be provided with trapped drains in cases where the exposure and the quantity of oil involved are such that removal of oil is important. Trench all around Exterior Oil-insulated Transformer 8.2 Dry-Type Transformers Installed Indoors.Transformers rated 112-1/2 KVA or less shall have separation of at least 300mm from combustible material unless separated there from by a fire-resistant heat-insulating barrier or unless of a rating not exceeding 600 volts and completely enclosed except for ventilating openings. Dry-type transformer 112-1/2 Kva or less 300mm Combustible Wall 8.3 Askarel-Insulated Transformers Installed Indoors.Askarel-insulated transformers rated in excess of 25 KVA shall be furnished with a pressure relief vent.Where installed in a poorly ventilated place they shall be furnished with a means for absorbing any gases generated by arcing inside the case, or the pressure relief vent shall be connected to a chimney or flue which will carry such gases outside the building.Askarel-insulated transformers rated more than 35,000 volts shall be installed in a vault. Transformersof more than 112-1/2 KVA rating shall be installed in a transformer room of fire-resistant construction unless they are constructed with Class B (80C rise) or Class H (150C rise) insulation, and are separatedfrom combustible material not less than 1.85m horizontally and 3.7m vertically or are separated there from by a fire-resistant heat-insulating barrier. Transformers rated more than 35,000 volts shall be installed in a vault. Dry-type transformer 112-1/2 Kva or less 1.85 m Combustible Wall Combustible ceiling 3.70 m vault Transformer more than 35,000 volts 8.4 Oil-Insulated Transformers Installed Indoors.Oil-insulated transformers shall be installed in a vault constructed as specified in this Section except as follows: 1.NOT OVER 112-1/2KVA TOTAL CAPACITY.The provisions for transformer vaults specifiedin Section 9.3 of this Rule apply except that the vault may be constructed of reinforced concrete not less than 100mm thick. 2.NOT OVER 600 VOLTS.A vault is not required provided suitable arrangementsare made where necessary to prevent a transformer oil fire igniting other materials, and the total transformer capacity in one location does not exceed 10 KVA in a section of the building classified as combustible, or 75 KVA wherethe surrounding structuresis classified as fire-resistant construction. > 100mm thick reinforced concrete vault oil insulated transformer < 112-1/2 KVa 8.5 Guarding.Transformers shall be guarded as follows: 1.MECHANICAL PROTECTION.Appropriate provisions shall be made to minimize the possibility of damage to transformers from external causes where the transformers are located exposed to physical damage. 2.CASE OR ENCLOSURE.Dry-type transformers shall be provided with a non-combustible moisture resistant case or enclosure which will provide reasonable protection against accidental insertion of foreign objects. 3.EXPOSED LIVE PARTS.The transformer installation shall conform with the provisions for guarding of live parts in PEC Rule 1056. 4.VOLTAGE WARNING.The operating voltage of exposed live parts of transformer installations shall be indicated by signs or visible markings on the equipment or structures. 3.FURNACE TRANSFORMERS.Electric furnace transformers of a total rating not exceeding 75 KVA may be installed without a vault in a building or room of fire-resistant construction provided suitable arrangements are made to prevent a transformer oil fire spreading to other combustible material. 4.DETACHED BUILDING.Transformers may be installed in a building which does not conform with the provisions specified in this Code for transformer vault, provided neither the building nor its contents present fire hazard to any other building or property, and provided the building is used only in supplying electric service and the interior is accessible only to qualified persons. 9. Provisions for Transformer Vaults 9.1 New Building.New buildings requiring an expected load demand of 200KVA or above shall be provided with a transformer vault, except that transformers may be mounted on poles or structures within the property if enough space is available, provided that all clearances required can be obtained and no troublesome contamination on insulators, bushings, etc. can cause hazards and malfunctioning of the equipment. 150 mm for R.C 200 mm for Brick 300 mm for Load bearing CHB 200 Kva or more Wall: 20 mm thick plaster 2-1/2 hours fire rating Floor: 100mm thick2-1/2 hours fire rating 9.2 Location.Transformer and transformer vaults shall be readily accessible to qualified personnel for inspection and maintenance.Vaults shall be located where they can be ventilated to the outside air without using flues or ducts wherever such an arrangement is practicable. 9.3 Walls, Roof and Floor.The walls and roofs of vaults shall consist of reinforced concrete not less than 150mm thick, masonry or brick not less than 200mm thick, or 300mm load bearing hollow concrete blocks.The inside wall and roof surface of vaults constructed of hollow concrete blocks shall have a coating of cement or gypsum plaster not less than 20mm thick.The vault shall have a concrete floor not less than 100mm thick.Building walls and floor which meet these requirements may serve for the floor, roof and one or more walls of the vaults.Other forms of fire-resistive construction are also acceptable provided they have adequate structural strength for the conditions and a minimum fire resistance of two and one half hours according to the approved Fire Test Standard.The quality of the material used in the construction of the vault shall be of the grade approved by the Building Official having jurisdiction. 9.4 Doorways.Any doorway leading from the vault into the building shall be protected as follows: 1.TYPE OF DOOR.Each doorway shall be provided with a tight-fitting door of a type approved for openings in such locations by the authority enforcing this Code. 2.SILLS.A door sill or curb of sufficient height to confine within the vault, the oil from the largest transformer shall be provided and in no case shall the height be less than 100mm. 3.LOCKS.Entrance doors shall be equipped with locks, and doors shall be kept locked, access being allowed only to qualified persons. Locks and latches shall be so arranged that the door may be readily and quickly opened from the inside. 10. Ventilation.Ventilation shall be adequate to prevent a transformer temperature in excess of the prescribed values. 1.LOCATION.Ventilation openings shall be located as far away as possible from doors, windows, fire escapes and combustible material. 2. ARRANGEMENT.Vaults ventilated by natural circulation of air may have roughly half of the total area of openings required or ventilation in one or more openings near the floor and the remainder in one or more openings in the roof or in the sidewalls near the roof; or all of the area required for ventilation may be provided in one or more openings in or near the roof. 3. SIZE.In the case of vaults ventilated to an outdoor area without using ducts or flues the combined net area of all ventilating openings after deducting the area occupied by screens, grating, or louvers, shall be not less than 0.006 sqmm per KVA of transformer capacity in service, except that the net area shall be not less than 0.1 sqm for any capacity under 50 KVA. 4. COVERING.Ventilation openings shall be covered with durable gratings, screens, or louvers, according to the treatment requirement required in order to avoid unsafe conditions. 5.DAMPERS.Where automatic dampers are used in the ventilation openings of vaults containing oil-insulated transformers, the actuating device should be made to function at a temperature resulting from fire and not a temperature which might prevail as a result of an overheated transformer or bank of transformers.Automatic dampers should be designed and constructed to minimize the possibility of accidental closing. 6. DUCTS.Ventilating ducts shall be constructed of fire resistant material. 7. DRAINAGE.Where practicable, vaults containing more than 100KVA transformer capacity shall be provided with a drain or other means which will carry off any accumulation of oil or water in the vaults unless local conditions make this impracticable. 8.WATER PIPES AND ACCESSORIES.Any pipe or duct system foreign to the electrical installation should not enter or pass through a transformer vault.Where the presence of such foreign system cannot be avoided, appurtenances thereto which require maintenance at regular intervals shall not be located inside the vault.Arrangements shall be made where necessary to avoid possible trouble from compensation, leaks and breaks in such foreign system.Piping or other facilities provided for fire protection or for water-cooled transformers are not deemed to be foreign to the electrical installation. 11. Capacitors. 1.Application. This section applies to installation of capacitors on electric circuits in or on buildings. Exception No. 1.Capacitors that are components of other apparatus shall conform to the requirements for such apparatus. Exception No. 2.Capacitors in hazardous locations shall comply with additional requirements in PEC Section 400-415. 2.Location.An installation of capacitors in which any single unit contains more than three gallons of combustible liquid shall be in a vault conforming to part C of PEC Section 319. 3.Mechanical Protection.Capacitors shall be protected from physical damage by location or by suitable fences, barriers or other enclosures. 4.Cases and Supports.Capacitors shall be protected from physical damage by location or by suitable fences, barriers or other enclosures. 5.Transformers Used with Capacitors.Transformers which are components of capacitor installations and are used for the purpose of connecting the capacitor to a power circuit shall be installed in accordance with PEC Section 319.The KVA rating shall not be less than 135 per cent of the capacitor rating in Kva. 12. Emergency Systems 1.The provisions of this Section shall apply to the installation, operation and maintenance of circuits, systems and equipment intended to supply illumination and power in the event of failure of the normal supply or in the event of accident to elements of a system supplying power and illumination essential for safety to life and proper where such systems or circuits are required by the Fire Code, or by any government agency having jurisdiction. Emergency systems are generally installed in places of assembly where artificial illumination is required, such as buildings subject to occupancy by large numbers of persons, hotels, theaters, sports arenas, hospitals and similar institutions.Emergency systems provide power for such functions as refrigeration, operation of mechanical breathing apparatus, ventilation essential to maintain life, illumination and power for hospital room, fire alarm systems, fire pumps, industrial processes where current interruption would produce serious hazards, public address systems and other similar functions. 2. All requirements of this Section shall apply to emergency systems. 3.All equipment for use on emergency systems shall be properly approved. 4. Tests and Maintenance a. The authority having jurisdiction shall conduct or witness a test on the complete system upon completion of installation, and periodically afterwards. b. Systems shall be tested periodically in accordance with a schedule acceptable to the authority having jurisdiction to assure that they are maintained in proper operating condition. c. Where the battery systems or unit equipment are involved, including batteries used for starting or ignition in auxiliary engines, the authority having jurisdiction shall require periodic maintenance. d. A written record shall be kept of such tests and maintenance. 5.Emergency systems shall have adequate capacity and rating for the emergency operation of all equipment connected to the system. 6. Current supply shall be such that in the event of failure of the normal supply to or within the building or group of buildings concerned, emergency lighting or emergency power, will be immediately available.The supply system for emergency purposes may be composed one or more of the types of systems covered in Section 12.7 to Section 12.10 of this Rule.Unit equipment in accordance with Section 12.21 shall satisfy the applicable requirements of this Section. Consideration must be given to the type of service to be rendered; whether for short duration, as for exit lights of a theater, or for long duration, as for supplying emergency power and lighting during long periods of current failure from trouble either inside or outside the buildings, as in the case of a hospital. Assignment of degree of reliability of the recognized emergency supply system depends upon the careful evaluation of the variables of each particular installation. 7.A storage battery of suitable rating and capacity shall supply, by means of a service installed according to Section 200 of the PEC and maintained at not more than 90 per cent of system voltage, the total load of the circuits supplying emergency lighting and emergency power for a period of at least hour. 8. A generator set driven by some form of prime mover, with sufficient capacity and proper rating to supply circuits carrying emergency lighting or lighting and power, equipped with suitable means for automatically starting the prime mover on failure of the normal service shall be provided.For hospitals, the transition-time from instant of failure of the normal power source to the emergency generator source shall not exceed ten seconds.(See Section 12.4) 9. There shall be two services, each in accordance with Section 200 of the PEC, widely separated electrically and physically to minimize the possibility of simultaneous interruption of power supply arising from an occurrence within the building or group of buildings served. 10. Connections on the line side of the main service shall be sufficiently separated from said main service to prevent simultaneous interruption of supply through an occurrence within the building or group of buildings served. 11.The requirements of Section 12.5 and Section 12.6 also apply to installations where the entire electrical load on a service or sub-service is arranged to be supplied from a second source.Current supply from a standby power plant shall satisfy the requirements of availability in Section 12.6. 12. Audible and visual signal devices shall be provided, where practicable, for the following purposes: a. To give warning of dearrangement of the emergency or auxiliary source. b. To indicate that the battery or generator set is carrying a load. c. To indicate when abattery charger is properly functioning. 13. Only appliances and lamps specified as required for emergency use shall besupplied by emergency lighting circuits. 14.Emergency illumination shall be provided for all required exit lights and all other lights specified as necessary for sufficient illumination. Emergency lighting systems should be so designed and installed that the failure of any individual lighting element, such as the burning out of a light bulb, shall not leave any area in total darkness. 15. Branch circuits intended to supply emergency lighting shall be so installed as to provide service immediately when the normal supply for lighting is interrupted.Such installations shall provide either one of the following: a. An emergency lighting supply, independent of the general lighting system with provisions for automatically transferring to the emergency lights by means of devices approved for the purpose upon the event of failure of the general lighting system supply. b. Two or more separate and complete systems with independent power supply, each system providing sufficient current for emergency lighting purposes.Unless both systems are used for regular lighting purposes and are both lighted, means shall be provided for automatically energizing either system upon failure of the other.Either or both systems may be part of the general lighting system of the protected occupancy if circuits supplying lights for emergency illumination are installed in accordance with other Section of this Rule. 16. For branch circuits which supply equipment classed as emergency, there shall be an emergency supply source to which the load will be transferred automatically and immediately upon the failure of the normal supply. 17. Emergency circuit wiring shall be kept entirely independent of all other wiring and equipment and shall not enter the same raceway, box or cabinet with other wiring except: a. In transfer switches, or b. In exit or emergency lighting fixtures supplied from two (2) sources. 18. The switches installed in emergency lighting circuits shall be so arranged that only authorized persons have control of emergency lighting, except: a. Where two or more single throw switches are connected in parallel to control a single circuit, at least one of those switches shall be accessible only to authorized persons. b. Additional switches which act only to put emergency lights into operation but not to disconnect them may be permitted. Switches connected in series and three- and four-way switches shall not be allowed. 19.All manual switches for controlling emergency circuits shall be located at the most accessible place to authorized persons responsible for their actuation.In places of assembly, such as theaters, a switch for controlling emergency lighting systems shall be located in the lobby or at a place conveniently accessible there from. In no case shall a control switch for emergency lighting in a theater for motion picture projection be placed in the projection booth or on the stage.However, where multiple switches are provided, one such switch may be installed in such locations and so arranged that it can energize but not disconnect for the circuit. 20. Lights on the exterior of the building which are not required for illumination when there is sufficient daylight may be controlled by an automatic light actuated device approved for the purpose. 21. In hospital corridors, switching arrangements to transfer corridor lighting in patient areas of hospitals from overhead fixtures to fixtures designed to provide night lighting maybe permitted,provided thatthe switching system is so designed that switches can only select between two sets of fixtures but cannot extinguish both sets at the sametime. 22. The branch circuits over current devices in emergency circuits shall be accessible to authorized persons only. 23.Where permitted by the authority having jurisdiction, in lieu of other methodsspecified elsewhere in this Section, individual unit equipment for emergency illumination shall consist of: a. Battery b. Battery charging means, when a storage battery is used c. One or more lamps, and d. A relaying device arranged to energize the lamps automatically upon failure of the normal supply to the building The batteries shall be of suitable rating and capacity to supply and maintain, at not less than 90 per cent of rated lamp voltage, the total lamp load associated with the unit for a period of at least hour.Storage batteries, whether of the acid or alkali type, shall be designed and constructed to meet the requirements of emergency service.Lead-acid type storage batteries shall have transparent jars. Unit equipment shall be permanently fixed in place and shall have all wiring to each unit installed in accordance with the requirements of any of the wiring methods discussed in Chapter II of the PEC.They shall not be connected by flexible cord.The supply circuit between the unit equipment and the service, the feeders or the branch circuit wiring shall be installed as required by Section 12.17.Emergency illumination fixtures which obtain power from a unit equipment which are not part of the unit equipment shall be wired to the unit equipment as required by Rule 5257 of the PEC and in accordance with the one of the wiring methods described in Chapter II of the PEC. 13. Effectivity 1. All primary and secondary supply lines already existing shall comply with the provisions of this Rule within two (2) years from the effectivity of this Rule. 2. Transformers to be installed on, attached to, or in buildings shall comply with the requirements of this Rule.Transformer installations already existing shall comply with the requirements within two (2) years from the effectivity of this Rule. 3. Non-compliance with the provisions of this Rule shall be subject to the penal provisions in Section 213 of PD 1096. THANK YOU