Electrical Systems PDF

ELECTRICAL SYSTEMS 1. GENERAL 1.1 DEFINITION OF ELECTRICITY a form of energy generated by friction, induction or chemical change, having magnetic, chemical and radiant effect. the motion of free electrons through a solid conductor. 1.2 SOURCES OF ELECTRICITY STORAGE B...

ELECTRICAL SYSTEMS 1. GENERAL 1.1 DEFINITION OF ELECTRICITY a form of energy generated by friction, induction or chemical change, having magnetic, chemical and radiant effect. the motion of free electrons through a solid conductor. 1.2 SOURCES OF ELECTRICITY STORAGE BATTERIES GENERATORS  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 current Alternating 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 – These furnish 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 ALTERNATING CURRENT – a DIRECT CURRENT – a current current which is periodically which flows at a constant time rate varying in time rate and in and in the same direction. direction. It rises from zero to maximum, falls to zero, reverses its direction and again returns to zero.  1.5 UNITS OF ELECTRICITY UNIT OF QUANTITY COULOMB – a coulomb of electricity comprises approximately 6.25 x 10 18 electrons. AMPERE – An ampere of current represents a rate of flow of one coulomb or 6.25 x 10 18 electrons/second through a given cross section. UNIT OF ELECTRIC POTENTIAL VOLT – is the electromotive force or potential difference between two points in an electric field which will move a charge of one coulomb between these points.  UNIT OF RESISTANCE OHM – The resistance which will allow one ampere of current to flow when one volt is impressed upon it. UNIT OF ELECTRIC POWER WATT – the unit of electric power or the rate of doing electrical work. UNIT OF ENERGY WATT-HOURS – the unit of energy or the capacity for doing work.  1.6 OHM’S 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.  1.7 ELECTRIC LOAD CONTROL – 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. LOAD SCHEDULING AND DUTY- CYCLE CONTROL – the installation’s electric loads are analyzed and scheduled to restrict demand by shifting large loads to off-peak hours and controlled to avoid coincident operation. DEMAND METERING ALARM – in conjunction with a duty cycle controller, demand is continuously metered and an alarm is set on when a predetermined demand level is exceeded. AUTOMATIC INSTANTANEOUS DEMAND CONTROL – also called “rate control”, it is an automated version of the demand metering alarm system, where it automatically disconnects or reconnects loads as required. IDEALCURVE CONTROL – This controller operates by comparing the actual rate of energy usage to the ideal rate, and controls KW demand by controlling the total energy used within a metering interval. FORECASTING SYSTEMS – are computerized systems which continuously forecast the amount of energy remaining in the demand interval, then examine the status and priority of each of the connected loads and decide on the proper course of action.  1.8 MEASURING ELECTRIC CONSUMPTION CURRENT LEADS LOAD POWER SOURCE KWH METERS – To WM measure energy, the VOLTAGE WATTMETER LEADS 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 SYSTEMS 2.1 BRANCH CIRCUITS An 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 CIRCUIT PARALLEL CIRCUIT  R1 R2 10 amp 10 amp SERIES CIRCUIT – is one in which the R3 components are connected in tandem. All ELEC SOURCE separate loads of the circuit carry the same equal current and the total 10 amp R5 R4 10 amp resistance, R, is the sum of the CIRCUIT IN SERIES resistances around the circuit. R = R1 + R2 + R3 + R4 + R5 PARALLEL CIRCUIT (or Multiple 3 amp Circuit) – is one in which the + 1 amp 1 amp 1 amp components or loads are so arranged that the current divides between them. ELECTRICAL R1 R2 R3 SOURCE Each outlet has a live wire connected to the current carrying wire of the circuit CIRCUIT IN PARALLEL and also a neutral wire or grounded wire connected to the return wire of the 1 R= circuit. With this system, the total current 1/R1 + 1/R2 + 1/R3 flowing through the circuit is the sum of the current flowing through each outlet.  CLASSIFICATIONS OF BRANCH CIRCUITS General Purpose Branch Circuit - GENERALLY 15, 20A LTG A supplies outlets for lighting and appliances, including convenience receptacles. Appliance Branch Circuit - supplies 15, 20, 30, or 50A A A outlets intended for feeding appliances. Fixed lighting is not supplied. Individual Branch Circuit - is SIZE REQUIRED SINGLE ITEM designed to supply a single specific item, FOR ITEM FED such as a motor load or a unit air- conditioner.  Branch Circuit The portion of an electrical system extending from the final overcurrent device protecting a circuit to the outlets served by the circuit 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 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 Low-Voltage electrical system 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 CIRCUITING GUIDELINES 1. General: Branch circuits shall be sufficient to supply a load of 30 watts per square meter (3 watts per square foot) in buildings excluding porches, garages and basements. 20 amp C3 C3 C3 2. In all but the smallest installations, connect lighting, convenience receptacles, and appliances in DINE KIT 20 amp separate circuits. The Code requires a C1 minimum of 2 - 20 amperes Range C4 C2 appliance branch circuit to feed all Ref small appliance outlets in the kitchen, pantry, dining and family room. 3. Convenience receptacles in an area shall be wired to at least two different circuits so that in case of failure in any one of the circuits, the entire area will not be deprived of power. 4. General purpose branch circuits shall be rated at 20 amperes wired with No. 12 AWG minimum. Switch legs may be No. 14 AWG if the lighting load permits. 5. Limit the circuit load for lighting and small appliances on 15 amp and 20 amp circuit loads and on 15 and 20 amp overcurrent devices respectively.  2.2 SINGLE PHASE ELECTRICAL SYSTEMS For homes and small commercial buildings A single phase electrical system can either be 2-wire or 3-wire and composes two hot legs and a neutral wire. SWITCH FUSE Two-Wire Single Phase DC or AC 110 V Three-Wire Single Phase DC 220 V (EDISON SYSTEM) 110 V Three-Wire Single Phase AC  2.2 THREE PHASE ELECTRICAL SYSTEMS For industries and large commercial buildings The Three Phase AC electricity is a Triple Circuit. The lighting and outlet loads are connected between any phase leg and a A B C neutral line. While machineries and other bigger loads are connected to the phase leg A only. Three-Wire Three Phase AC B A-B 220V A-C 220V C B-C 220V MOTOR Four-Wire Three-Phase AC A N B C 220V 220V 110V 220V 110V 110V 2.3 COMPONENTS OF THE BUILDING ELECTRICAL SYSTEM  Service The supplying of utilities required or demanded by the public Substation An auxiliary power station where electrical current is converted or where voltage is stepped up or down 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 Service Drop The portion of a service conductor extending The overhead portion of service from a service drop or service lateral to the conductors extending from the service equipment of a building nearest utility pole to a building Service Lateral Watt-Hour Meter The underground portion of service A meter for measuring and recording the conductors extending from a main quantity of electric power consumed with power line or transformer to a respect to time building Feeder Transformer Vault Switchgear Room Any of the conductors A fire-rated room housing Contains the service extending from the a transformer and equipment for a large service equipment to auxiliary equipment for a building various distribution large building points in a building Service Equipment Equipment necessary for controlling, metering and protecting the electric Standby Generator power supply to a builidng For providing emergency power during a power outage. Switchboard Unit Substation One or a group of panels on A freestanding enclosure Uninterruptible Power Supply which are mounted switches, housing a disconnect An emergency system designed overcurrent devices, switch, a step-down to provide pwer automatically and metering instruments and transformer and instantaneously buses switchgear 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  Service Conductors extend from a main power line or transformer to the service equipment of a building 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 Direct burial cable may be used for from a main power line or transformer to a building residential service connections Servcie Entrance Conductor The portion of a service conductor extending from a service drop or service lateral to the service equipment of a building 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 Watt-Hour Meter transformer may be placed on an outdoor pad. If located within a Measures and records the quantity of electric power building, oil-filled transformers require a well-ventilated, fire-rated consumed with respect to time. Supplied by the public utility, vault with two exits and located on an exterior wall adjacent to the it is always placed ahead of the main disconnect switch so switchgear room. Dry-type transformers used in small- and that it cannot be disconnected medium-sized buildings may be replaced together with a disconnect switch and switchgear in a unit substation For multiple-occupancy buildings, banks of meters are installed so that each unit can be metered independently The service switch is the main disconnect for the entire electrical Grounding Rod or Electrode system of a building, except for any Is firmly embedded in the earth to establish a ground emergency power systems. connection The service equipment includes a main To panelboards 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 is a set of conductors which extends from the main switchboard to a distributing center (panel board) with no other circuits connected to it between the source and the distributing center. SUB-FEEDER CIRCUITS – are line extensions of a feeder, fed through a panel board or cut-out, or from one distributing center to another and having no other circuit connected to it between the two distributing centers. A sub-feeder serves to distribute power from the main feeders to smaller local panel boards, called sub-panel boards. BRANCH CIRCUITS – These are small capacity conductors which deliver energy to lamps, motors and other loads within the circuit. PANEL BOARDS AND SUB-PANEL BOARDS (also called CUT-OUTS) – These serve to control and protect the sub feeders and branch circuits. UTILIZATION EQUIPMENT – These are the lighting, power and motor loads and wiring devices which are directly handled and utilized by users.  Fuse A device containing a strip or wire of fusible metal that melts under the heat produced by Service Switch excess current thereby The main disconnect for the entire interrupting the circuit 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 Circuit Breaker panelboard. A switch that automatically interrupts an electric circuit to prevent excess current from damaging Bus apparatus in the circuit or from causing a fire. A A heavy conductor, usually in the form of a circuit breaker may be reclosed and reused without solid copper bar, used for collecting, carrying replacement of any components. Also called a and distributing large electric currents. Also breaker. called a busbar Grounded Conductor Any conductor of an electrical system intentionally connected to a ground connection Grounding Electrode Ground Wire A conductor, as a metal ground rod, A conductor connecting ground plate or cold-water pipe, firmly electric equipment or a embedded in the earth to establish a circuit to a ground gorund connection connection. Also called a grounding conductor 2.4 ILLUSTRATING THE COMPONENTS OF THE BUILDING ELECTRICAL SYSTEM BLOCK DIAGRAM A horizontal single line diagram of the building’s 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.  HIGH-VOLTAGE SINGLE LINE PRIMARY FEEDERS 2,400, 4,160, 7,200 DIAGRAM OR 13,200 VOLTS When electrical SECONDARY SERVICE MAIN DISTRIBUTION symbols are used FEEDERS PANELS CONDUCTORS RECEPTACLES in lieu of the MAIN TRANSFORMER SWITCH LIGHTING blocks, it is called MOTOR VAULT 120/208 OR BOARD 120/240 OR PANELS a “one line” or a SWITCHES 227/480 VOLTS LARGE LIGHTING/ “single line TRANSFORMER FUSES MOTOR APPLIANCE PANELS SMALL diagram”. BRANCH MOTORS & CIRCUIT CONTROL  ELEVATORS PP MACHINE MR ROOF ROOM LP 5A 5B 5C RISER 4A 4B 4C DIAGRAM LEFT 3A 3B 3C Is a vertical line RISER CENTRAL RISER SHAFT diagram of the 2A 2B 2C major electrical RIGHT RISER components of 1A LP 1B 1C the buildings LOBBY electrical system presented SPARE M.C.C. showing the MACHINE ROOM spatial relations between FIRE ALARM FA PANEL components. LPSE STAIR AND EXIT PANEL M METERING 2.5 EMERGENCY ELECTRIC SUPPLY SYSTEM Emergency Systems – provide electric power and illumination essentially for life safety and protection of property during an emergency, such as, electricity for exit lighting, elevators, fire alarm systems, fire pumps and the like. Standby Systems – provide power to selected loads not directly involved with life safety, such as, water and sewage treatment plants and industrial machines for manufacturing processes.  EMERGENCY POWER EQUIPMENT Battery Equipment – Central storage batteries are mounted in individual racks and always provided with automatic charging equipment. Engine-Generator Sets – are machines intended to produce electricity and composed of three components: the machine and its housing (if any), fuel storage tank and the exhaust facilities. EMERGENCY WIRING SYSTEMS USING THE BATTERY Small emergency appliance connected direct to a storage battery Groups of emergency loads connected to central storage battery through automatic device Emergency equipment loads are entirely separate from normal loads and are generally de-energized. The contactor is activated when it senses power loss. EMERGENCY WIRING SYSTEMS USING THE GENERATOR Emergency system handled by a single transfer switch which automatically turns on when it senses power loss at its downstream location. Emergency system handled by multiple switches Emergency service totally separated from normal through its own emergency service entrance, coming from different transformers or feeders. Same as above, but both service entrances supply normal loads and each act as standby for each other. 3. ELECTRICAL MATERIALS AND EQUIPMENT 3.1 CONDUCTORS – are materials which allow the free flow of electrons through them. Wires – are single insulated conductors No. 8 AWG (American Wire Gauge or smaller; for the English System, it is the B & S Gauge or Browne and Sharpe Gauge. The smallest size of wire permitted is No. 14. Cables – are single insulated conductors No. 6 AWG or larger; or they may be several conductors of any size assembled into a single unit. Bus Bars – large conductors which are not circular in cross section and usually found only to supply the main switch boards.  CONDUCTOR SIZES – AWG/MCM STANDARD All conductor sizes from No. 16 to No. 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 ½”  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 ½ inch in diameter is 500 mils in diameter, or 250,000 circular mils in area, (500)2 or 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 Conductor current carrying capacity or ampacity is the maximum operating temperature that its insulation can stand continuously. Heat is generated as a result of the current flowing and the conductor resistance. When conductors are placed in an enclosed conduit, the heat generated is not as easily dissipated as it would be if the conductor were free in the air. Thus, the current rating of a conductor in free air is much higher than that for the same were it in a conduit.  TYPES OF CABLES Armored Cable (Type AC) – a fabricated assembly of insulated conductors enclosed in flexible metal sheath. Metal Clad Cable (Type MC) – a factory assembled cable of one or more conductors each individually insulated and enclosed in a metallic sheath of interlocking tape of a smooth or corrugated tube. Mineral Insulated Cable (Type MI) – a factory assembled conductor/s insulated with a highly compressed refractory mineral insulation enclosed in a liquid and gas tight continuous copper sheath. Non-Metallic Sheathed Cable (Type NM or NMC) – also known by the trade name ROMEX, is a factory assembly of two or more insulated conductors having a moisture resistant, flame retardant, and non-metallic material outer sheath.  Shielded Non-Metallic Sheathed Cable (Type SNM) – a factory assembly of two or more insulated conductors in an extruded core of moisture resistant and flame retardant material covered within an overlapping spiral metal tape. Underground Feeder and Branch Circuit Cable (Type UF) – a moisture resistant cable used for underground connections including direct burial in the ground as feeder or branch circuit. Service Entrance Cable (Type SE or USE) – a single or multi-conductor assembly provided with or without an overall covering primarily used for service wire. Power and Control Tray Cable (Type TC) – a factory assembled two or more insulated conductors with or without associated bare or covered grounding under a metallic sheath and is used for installation in cable trays, raceways, or where supported by wire. Flat Cable Assemblies (Type FC) – an assembly of parallel conductors formed integrally with an insulating material web designed specially for field installation in square structural channels. Flat Conductor Cable (Type FCC) – consists of three or more flat copper conductors placed edge to edge separated and enclosed within a insulating assembly. This type of cable is used for appliance or individual branch circuits installed inside floor surfaces. Medium Voltage Cable (MV) – a single or multi-conductor solid dielectric insulated cable rated at 2,000 to 35,000 volts. Trade name is Medium Voltage Solid Dielectric.  3.2 INSULATORS INSULATORS are materials which prevent the flow of electrons through them.  TYPES OF INSULATORS General Wiring Trade name Type Maximum Application Letter Operating Provisions Temperatur e Moisture-& heat-resistant RHW 75O C Dry and wet rubber 167O F Locations Thermoplastic T 60O C Dry locations 140O F Moisture-resistant TW 60O C Dry and wet thermoplastic 140O F Locations Heat-resistant THHN 90O C Dry locations thermoplastic 194O F Moisture-& heat-resistant THW 75O C Dry and wet thermoplastic 167O F Locations Moisture-& heat-resistant THWN 75O C Dry and wet thermoplastic 167O F Locations Moisture-& heat resistant XHHW 90O C Dry locations cross-linked 194O F Wet thermosetting 75O C locations polyethelene 167O C Silicone-asbestos SA 90O C Dry locations 194O F Asbestos and Varnished AVA 110O C Dry locations Cambric 230O F only 3.3 CONDUITS CONDUITS are circular raceways used to enclose wires and cables and are of metal or plastic (PVC). To protect the enclosed conductors from mechanical injury and chemical damage. To protect people from shock hazards 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. 3.4 RACEWAYS – are channels or wiring accessories so designed for holding wires, cables and bus bars that 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. Convenience Outlet or Attachment Cap - the complete set-up which establishes connection between the conductor of the flexible cord and the conductors connected permanently to the receptacle.  Lighting Outlet – is an outlet intended for direct connection to a lamp holder, lighting fixture, or pendant cord terminating in a lamp holder. Receptacle Outlet – is an outlet where one or more receptacles are installed. 3.6 SWITCHES – are devices for making, breaking, or changing conditions in an electrical circuit under the conditions of load which they are rated. TYPE OF SWITCH – ACCORDING TO VOLTAGE Switches are rated as 250V, 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.  3. Wiring Switches – include all the relatively small switches that are  TYPE OF SWITCH - ACCORDING employed in interior wiring TO TYPE OF SERVICE installations for the control of branch circuits, individual lamps or 1. Service Switch – intended to appliances. disconnect all the electric service in the building except emergency a) General–purpose switches – are equipment. This may comprise one to single-pole or double-pole switches six properly rated switches that are for the general purpose use of assembled into a switchboard. connecting or cutting-off circuits for the control of lamps or other loads 2. Power Switches – from a single point. a) General –purpose switches – are b) Three-way switches – are used intended for use in general where it is desired to control lamps distribution and branch circuits. from two different points, as in a stairwell. b) Disconnecting or isolating switches – are intended for disconnecting or c) Four-way switches – are used in isolating circuits; used for circuits conjunction with two 3-wire switches rated at more than 600 volts. where it is desired to control lamps from three or more desired points.   TYPE OF SWITCH - ACCORDING TO d) Electrolier or multi-circuit switches – OPERATION MECHANISM are used for the control of lights in Wiring switches may also be classified multi-lamp fixtures so that one according to the operating mechanism lamp or set of lamps may be turned as: on alone or in combination with 1. Rotary switch other lamps. 2. Push-button switch 3. Toggle or tumbler switch e) Momentary contact switches – are used where it is desired to connect  TYPE OF SWITCH - ACCORDING TO or cut-off a circuit for only a short NUMBER OF POLES AND THROWS duration. The switch is provided with a spring so that it will return to 1. Poles – that part of the switch which is its original position as soon as the used for making or breaking of a handle or button is released. connection and which is electrically insulated from other contact making or f) Dimmer switches – a rheostat or breaking parts. similar device for regulating the intensity of an electric light without 2. Throws - a single throw switch is one appreciably affecting spatial which will make a closed circuit only distribution. Also called a dimmer. when the switch is thrown in one Wiring switches may either be the position. A double throw switch will flush type, surface type or the make a closed circuit when thrown in pendant type. either of two positions. SPECIAL SWITCHES 1. Time Controlled Switches – This 5. Float Switch – a switch controlled by device comprises a precision low a conductor floating in a liquid. speed miniature drive motor (timer) to which some type of electric 6. Mercury Switch – an especially quiet contact-making device is connected. switch that opens and closes an electric circuit by shifting a sealed glass tube of 2. Remote Control (RC) Switches – A mercury so as to uncover or cover the contactor, or more specifically, a contacts. relay, that latches after being operated wireless from a distance. 7. Key Switch – a switch operated only by inserting a key or a card. Also called 3.Air Switch – a switch in which the a card switch. interruption of a circuit occurs in air. 8. Automatic Transfer Switch (ATS) – 4. Knife Switch – a form of air switch in This device, an essential part of an which a hinged copper blade emergency or standby service, is is placed between two basically a double throw switch, contact clips. 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). 3.8 OVER-CURRENT CIRCUIT PROTECTIVE DEVICES – are devices whose sole purpose is to protect insulation, wiring, switches and other apparatus from overheating or burning, due to overloads, to faults or to short circuits, by automatically cutting off the 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. GROUND FAULT CIRCUIT INTERRUPTERS (GFCI or GFI) – is an over current protective device that will provide ground fault protection as well as function as an ordinary circuit breaker. PANELBOARDS – popularly known as “panel” or “electrical panel”, it is simply the box wherein the protective devises are housed from which the circuits and bus bars terminate. SWITCHBOARDS – are free standing assemblies of switches, fuses, and/or circuit breakers whose function normally is to provide switching and feeder protection to a number of circuits connected to a main source. UNIT SUBSTATIONS – (Transfer Load Centers) an assembly of primary switch- fuse-breaker, step-down transformer, meters, controls, bus bars and secondary switchboard. It is used to supply power from a primary voltage line to any large facility. 4. WIRING SYSTEMS 4.1 WIRING METHODS KNOB AND TUBE WIRING – an obsolete wiring system consisting of single insulated conductors secured to and supported on porcelain knobs and tubes. When wires run through walls, 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. FLEXIBLE METAL CONDUIT WIRING – Its installation is much easier and quicker than that of rigid metal conduits. Unlike the rigid conduits which come in short lengths of 10 ft. (3 M), flexible metal conduit wiring comes in length of 25 ft – 250 ft (8 M – 83 M) depending on the size of the conduit. ARMORED CABLE WIRING (BX WIRING) – consists of rubber or thermoplastic covered wire protected from injury to a certain extent from dampness by one or two layers of flexible steel armor. SURFACE METAL RACEWAY WIRING – the wires are supported on a thin sheet steel casing. The raceway is installed exposed, being mounted on the walls or ceiling. Metal raceways must be continuous from outlet to outlet or junction box, designed especially for use 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. LIGHTING TRACK – a factory- assembled channel with conductors for one to four circuits permanently installed in the track that will act as light duty (branch circuit) plug-in busways. CABLE TRAY / OPEN RACEWAY – is a continuous open support for approved cables. When used as a general wiring system, the cables must be self-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 system for 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. CEILING RACEWAY SYSTEMS – under-the-ceiling raceways composed of header ducts and distribution ducts separate for power and telephone cabling. They permit very rapid changes in layouts at low cost and are therefore particularly desirable in stores where frequent display transformations necessitate corresponding electrical facility adjustments. PRE-WIRED CEILING DISTRIBUTION SYSTEMS – are ceiling raceways that are pre-wired in the factory and plugged in where required.  ELECTRICAL SYMBOLS FEEDER L LAMP HOLDER PUSH BUTTON BRANCH CIRCUIT-CEILING/WALL PS LAMP HOLDER WITH PULL SWITCH BELL BRANCH CIRCUIT-FLOOR C CLOCK OUTLET 3&4 WIRES CIRCUIT NO. BUZZER MARK INDICATES 2 WIRES D DROP CORD OUTLET CH CHIME CROSSING WIRES F FAN OUTLET CONNECTING WIRES ANNUNCIATOR R RADIO OUTLET LIGHTING OUTLET CEILING FLOOR OUTLET LIGHTING PANEL POWER PANEL DUPLEX CONVENIENCE OUTLET RECESSED CEILING OUTLET FUSE DASH INDICATES SHAPE OF CONVENIENCE OUTLET SPLIT-WIRED FIXTURE WH WATT-HOUR METER WEATHER PROOF OUTLET WP T TRANSFORMER LIGHTING OUTLET WALL OUTLET AND SWITCH S J JUNCTION BOX RANGE OUTLET R FLUORESCENT LAMP SPECIAL PURPOSE OUTLET GROUND REFRIGERATOR OUTLET ref 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. Pole ≤ 500 mm Property line 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. ≥7.5 m ≥10 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 are located at street corners, poles and towers shall not be set so far from the corners as to make necessary the use of flying taps which are inaccessible 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 necessary for fire fighting. 2 - 2.5 m ≥ 15 m Pole 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. Voltage of Supply Horizontal Vertical Clearance Conductors Clearance in in Meters Meters 300 to 8,700 volts 1.0 2.5 8,700 to 15,000 2.5 2.5 volts 15,000 to 50,000 3.0 3.0 volts > 50,000 volts 3.0 + 10 mm per Kv 3.0 + 10 mm per Kv in excess in excess 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. 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 Supply Conductors/Supply of Conductors of 300 volts or more shall 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 Communication LInes Supply LInes conductors from - In general On jointly used In general (0 to On jointly used Exceeding 8700 poles 8700 volts) poles (0 to 8700 volts, add for each volts) 1000 volts of excess Vertical and lateral 75 mm 75 mm 75 mm 75 mm 6.25 mm conductors of the same circuit Vertical and lateral 75 mm 75 mm 150 mm 150 mm 10 mm conductors of other circuits Span and guy wires 75 mm 150 mm 150 mm 150 mm 10 mm attached to same pole: general Span and guy wires 75 mm 150 mm 300 mm 300 mm 10 mm attached to same pole: when parallel to line Lightning protection 75 mm 75 mm 75 mm 75 mm 5 mm wires parallel to line: surfaces of cross arms Lightning protection 75 mm 125 mm 75 mm 125 mm 5 mm wires parallel to line: surfaces of poles 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: Service Drop Conductor ≥ 2.5 m < 600 volts Highest point 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. Service Drop Conductor ≥1 m ≤300 volts Highest point 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. ≥500mm Service Drop Conductor ≤ 1.2 m ≤ 300 volts Highest point 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 ≥3m platform 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. ≥ 500mm window ≥1m 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. Service drop of communication line ≥ 5.50 m ≥5.50 m Service Drop of communication lines shall have a minimum clearance of 3m above ground at its point of attachment to the building or pedestal. ≥3m ≥3m protector 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 ≥3m Service drop conductor Swimming pool 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. Exterior Oil-insulated Transformer Trench all around 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. Combustible Wall Dry-type transformer 112-1/2 Kva or less ≥ 300mm  Transformers of 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 (80ºC rise) or Class H (150ºC rise) insulation, and are separated from 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. vault Combustible ceiling Dry-type transformer Transformer more Combustible 112-1/2 Kva or less ≥ 3.70 m Wall than 35,000 volts ≥ 1.85 m 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. 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 specified in 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 arrangements are 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 where the surrounding structures is classified as fire-resistant construction. > 100mm thick reinforced concrete vault oil insulated transformer < 112-1/2 KVa  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. 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. 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 Wall: 200 Kva or more 20 mm thick plaster 2-1/2 hours fire rating Floor: 100mm thick 2-1/2 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 ½ 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 a battery charger is properly functioning. 13. Only appliances and lamps specified as required for emergency use shall be supplied 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 that the switching system is so designed that switches can only select between two sets of fixtures but cannot extinguish both sets at the same time. 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 methods specified 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 ½ 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