Electrical Systems BU2 Reviewer PDF

CONDUCTOR SIZES – 3. ELECTRICAL MATERIALS AND EQUIPMENT AWG/MCM STANDARD 3.1 CONDUCTORS All conductor sizes from No. 16 to – are materials which allo...

CONDUCTOR SIZES – 3. ELECTRICAL MATERIALS AND EQUIPMENT AWG/MCM STANDARD 3.1 CONDUCTORS All conductor sizes from No. 16 to – are materials which allow the free No. 0000 (also designated 4/0) are flow of electrons through them. expressed in AWG. Beyond AWG No. 4/0, a different Wires – are single insulated designation, MCM (or thousand circular mil) conductors No. 8 AWG (American Wire is used. In this designation, the smallest Gauge or smaller; for the English MCM size is 250 MCM or ½”  and the System, it is the B & S Gauge or biggest is 500 MCM. Browne and Sharpe Gauge. The A circular MIL is an artificial area smallest size of wire permitted is No. measurement, representing the square of 14. the cable diameter (diam2) when the Cables – are single insulated diameter is expressed in mils (thousands of conductors No. 6 AWG or larger; or an inch). Thus a solid conductor ½ inch in they may be several conductors of diameter is 500 mils in diameter, or any size assembled into a single unit. 250,000 circular mils in area, (500)2 or 250 MCM; thus; Bus Bars – large conductors which CM/1000 = diam2 = (500)2/1000 = are not circular in cross section and 250,000/1000 = 250 MCM usually found only to supply the main In the metric system, conductor sizes are switch boards. given simply as the diameter in millimeters (mm). TYPES OF CABLES CONDUCTOR AMPACITY Armored Cable (Type AC) – a fabricated assembly of insulated conductors enclosed in flexible metal sheath. Metal Clad Cable (Type MC) – a factory Conductor current carrying capacity or assembled cable of one or more ampacity is the maximum operating conductors each individually insulated temperature that its insulation can stand and enclosed in a metallic sheath of continuously. Heat is generated as a interlocking tape of a smooth or result of the current flowing and the corrugated tube. conductor resistance. When conductors Mineral Insulated Cable (Type MI) – a are placed in an enclosed conduit, the factory assembled conductor/s insulated heat generated is not as easily with a highly compressed refractory dissipated as it would be if the conductor mineral insulation enclosed in a liquid and were free in the air. Thus, the current gas tight continuous copper sheath. rating of a conductor in free air is much higher than that for the same were it in Non-Metallic Sheathed Cable (Type NM a conduit. 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 Flat Cable Assemblies (Type FC) – an (Type SNM) – a factory assembly of two assembly of parallel conductors formed or more insulated conductors in an integrally with an insulating material web extruded core of moisture resistant and designed specially for field installation in flame retardant material covered within square structural channels. an overlapping spiral metal tape. Underground Feeder and Branch Circuit Cable (Type UF) – a moisture resistant Flat Conductor Cable (Type FCC) – cable used for underground connections consists of three or more flat copper including direct burial in the ground as conductors placed edge to edge feeder or branch circuit. separated and enclosed within a Service Entrance Cable (Type SE or insulating assembly. This type of cable USE) – a single or multi-conductor is used for appliance or individual assembly provided with or without an branch circuits installed inside floor overall covering primarily used for service surfaces. wire. Power and Control Tray Cable (Type TC) – a factory assembled two or more insulated Medium Voltage Cable (MV) – a conductors with or without associated bare single or multi-conductor solid dielectric or covered grounding under a metallic sheath insulated cable rated at 2,000 to and is used for installation in cable trays, 35,000 volts. Trade name is Medium raceways, or where supported by wire. Voltage Solid Dielectric. 3.2 INSULATORS TYPES OF INSULATORS INSULATORS are materials which General Wiring prevent the flow of electrons through them. 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  TYPES OF STEEL CONDUITS 3.3 CONDUITS CONDUITS are circular raceways used Heavy-wall steel conduits called “Rigid to enclose wires and cables and are of Steel Conduits” or RSC with an metal or plastic (PVC). approximate thickness of 0.117 mm. To protect the enclosed conductors “Intermediate Metal Conduit” or IMC with from mechanical injury and chemical thickness of 0.071 mm. damage. Thin-wall steel conduits named “Electric Metal Tubing” or EMT. To protect people from shock hazards by providing a grounded enclosure. RSCs and IMCs use the same fitting, called condulets, and are threaded alike at the To provide a system ground path. joints. EMTs are not threaded but use set screw and pressure fitting and are not recommended for embedding in concrete To protect the surroundings against fire nor permitted in hazardous areas. IMCs hazard as a result of overheating or short yield a larger inside diameter (ID) for circuiting of the enclosed conductors. easier wire pulling and is lighter than the RSC. To support the conductors. 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.  3.6 SWITCHES – are devices for making, breaking, or changing conditions in an electrical circuit under the conditions of Lighting Outlet – is an outlet intended load which they are rated. for direct connection to a lamp holder, lighting fixture, or pendant cord TYPE OF SWITCH – ACCORDING terminating in a lamp holder. 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. Receptacle Outlet – is an outlet where 2. Heavy Duty (HD) – intended for one or more receptacles are installed. frequent interrupting. 3. Light Duty (LD) –intended to connect the loads occasionally, such as service switches.  TYPE OF SWITCH - ACCORDING TO 3. Wiring Switches – include all the d) Electrolier or multi-circuit switches – OPERATION MECHANISM relatively small switches that are are used for the control of lights in  TYPE OF SWITCH - ACCORDING Wiring switches may also be classified employed in interior wiring multi-lamp fixtures so that one TO TYPE OF SERVICE according to the operating mechanism installations for the control of lamp or set of lamps may be turned as: branch circuits, individual lamps or on alone or in combination with 1. Service Switch – intended to 1. Rotary switch appliances. other lamps. disconnect all the electric service in 2. Push-button switch the building except emergency a) General–purpose switches – are 3. Toggle or tumbler switch single-pole or double-pole switches e) Momentary contact switches – are equipment. This may comprise one to used where it is desired to connect six properly rated switches that are for the general purpose use of  TYPE OF SWITCH - ACCORDING TO connecting or cutting-off circuits for or cut-off a circuit for only a short assembled into a switchboard. NUMBER OF POLES AND THROWS the control of lamps or other loads duration. The switch is provided from a single point. with a spring so that it will return to 2. Power Switches – 1. Poles – that part of the switch which is its original position as soon as the used for making or breaking of a b) Three-way switches – are used handle or button is released. a) General –purpose switches – are connection and which is electrically intended for use in general where it is desired to control lamps insulated from other contact making or from two different points, as in a f) Dimmer switches – a rheostat or distribution and branch circuits. breaking parts. stairwell. similar device for regulating the intensity of an electric light without b) Disconnecting or isolating switches – 2. Throws - a single throw switch is one c) Four-way switches – are used in appreciably affecting spatial are intended for disconnecting or which will make a closed circuit only conjunction with two 3-wire switches distribution. Also called a dimmer. isolating circuits; used for circuits when the switch is thrown in one where it is desired to control lamps Wiring switches may either be the rated at more than 600 volts. position. A double throw switch will from three or more desired points. flush type, surface type or the make a closed circuit when thrown in pendant type. either of two positions. SPECIAL SWITCHES 3.7 WALL PLATES OR FACEPLATES - These are coverings for switches and wall 1. Time Controlled Switches – This 5. Float Switch – a switch controlled by outlets usually made of metal or of device comprises a precision low a conductor floating in a liquid. phenollic compound (Bakelite). 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. 3.8 OVER-CURRENT CIRCUIT PROTECTIVE DEVICES – are devices whose sole purpose is to protect CIRCUIT BREAKERS– is an over- insulation, wiring, switches and other current protective device designed to apparatus from overheating or burning, function as a switch, or it can be due to overloads, to faults or to short manually tripped and thus act as a circuits, by automatically cutting off the circuit switch. It breaks a circuit with an circuit. automatic tripping device without injury to itself. 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 GROUND FAULT CIRCUIT also pass through this metal. 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 4. WIRING SYSTEMS the box wherein the protective devises are housed from which the circuits and bus 4.1 WIRING METHODS bars terminate. KNOB AND TUBE WIRING – an obsolete wiring system consisting of single insulated conductors secured to and supported on porcelain knobs and SWITCHBOARDS – are free standing tubes. When wires run through walls, assemblies of switches, fuses, and/or they are inserted into a nonmetallic fire- circuit breakers whose function normally resistant tubing called a loom. is to provide switching and feeder protection to a number of circuits RIGID METAL CONDUIT WIRING – connected to a main source. is the best and most expensive among the usual type of wiring. Its advantages are: 1. it is fireproof; UNIT SUBSTATIONS – (Transfer Load 2. moisture proof; Centers) an assembly of primary switch- 3. it is mechanically strong so that nails fuse-breaker, step-down transformer, cannot be driven through it and it is not meters, controls, bus bars and secondary readily deformed by blows; switchboard. It is used to supply power 4. it resists the normal action of cement from a primary voltage line to any large when embedded in concrete or masonry. facility. FLEXIBLE METAL CONDUIT FLAT CABLE ASSEMBLIES – a field WIRING – Its installation is much installed rigidly mounted square easier and quicker than that of rigid structural channel (1 – 5/8” standard) metal conduits. Unlike the rigid conduits designed to carry 2 to 4 conductors (No. which come in short lengths of 10 ft. (3 10 AWG) and will act as light duty M), flexible metal conduit wiring comes (branch circuit) plug-in busways. in length of 25 ft – 250 ft (8 M – 83 M) depending on the size of the conduit. LIGHTING TRACK – a factory- ARMORED CABLE WIRING (BX assembled channel with conductors for WIRING) – consists of rubber or one to four circuits permanently thermoplastic covered wire protected installed in the track that will act as from injury to a certain extent from light duty (branch circuit) plug-in dampness by one or two layers of flexible busways. steel armor. SURFACE METAL RACEWAY WIRING – the wires are supported on a CABLE TRAY / OPEN RACEWAY thin sheet steel casing. The raceway is – is a continuous open support for installed exposed, being mounted on the approved cables. When used as a walls or ceiling. Metal raceways must be general wiring system, the cables continuous from outlet to outlet or must be self-protected, jacketed junction box, designed especially for use types, type TC. with metal raceways.   FLOOR RACEWAYS – The NEC recognizes three types of floor CEILING RACEWAY SYSTEMS – raceways: under-the-ceiling raceways composed of header ducts and distribution ducts 1. Underfloor Ducts (UF) installed beneath separate for power and telephone cabling. or flush with the floor. These underfloor They permit very rapid changes in layouts ducts usually requires a triple duct at low cost and are therefore particularly system for power, telephone and desirable in stores where frequent display signal cabling. transformations necessitate corresponding electrical facility adjustments. 2. Cellular Metal Floor Raceway – Found usually in office landscaping, it is an integrated structural/electrical system in a cellular metal floor. PRE-WIRED CEILING DISTRIBUTION 3. Precast Cellular Concrete – made of SYSTEMS – are ceiling raceways that are concrete cells fed from header ducts, pre-wired in the factory and plugged in which are normally installed in concrete where required. 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. ELECTRICAL SYMBOLS LIGHTING LAYOUT PLAN 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  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 2.3 Primary lines shall have a minimum vertical clearance of 10 m Location (APL) plan from the Municipal Engineer. from the crown of the pavement when crossing the highway and 7.5 m from the top of the shoulder or sidewalk when installed 2.2 Poles and transformer supports shall be located not more than along the side of the highway or street in a highly urbanized area. 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. ≥7.5 m ≥10 m Pole ≤ 500 mm Property line 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 3. Attachments on and Clearances from Buildings others and their guys and braces measured from the nearest parts of the objects concerned: 3.1 Attachments for support of power lines and cables, transformers and other A. From Fire Hydrants, not less than 5 m. equipment and/or communications lines installed on buildings shall be B. From the Street Corners, where hydrants are covered by an Approved Attachment Plan from the local Building Official. located at street corners, poles and towers shall not be set so far from the corners as to make 3.2 Where buildings exceed 15 m in height, overhead lines shall be arranged necessary the use of flying taps which are where practicable so that a clear space or zone at least 2 m wide will be inaccessible from the poles. left, either adjacent to the building or beginning not over 2.5 m from the C. From Curbs, not less than 150 mm measured from building, to facilitate the raising of ladders where necessary for fire the curb away from the roadway. fighting. 2 - 2.5 m ≥5 m ≥150 mm ≥ 15 m Pole 4. Open Supply Conductors Attached to Buildings 4.4 Clearance of wires from building surface shall be not less than Where the permanent attachment of open supply conductors of any class to those required Table II. buildings is necessary for an entrance such conductors shall meet the following requirements: Voltage of Supply Horizontal Vertical Clearance 4.1 Conductors of more than 300 volts to ground shall not be carried along or Conductors Clearance in in Meters near the surface of the buildings unless they are guarded or made Meters inaccessible. 300 to 8,700 volts 1.0 2.5 4.2 To promote safety to the general public and to employees not authorized 8,700 to 15,000 2.5 2.5 to approach conductors and other current-carrying parts of electric supply volts lines, such parts shall be arranged so as to provide adequate clearance 15,000 to 50,000 3.0 3.0 from the ground or other space generally accessible, or shall be provided volts with guards so as to isolate them effectively from accidental contact by > 50,000 volts 3.0 + 10 mm per Kv 3.0 + 10 mm per Kv such persons. in excess in excess 4.3 Undergrounded metal-sheathed service cables, service conduits, metal fixtures and similar noncurrent-carrying parts, if located in urban districts 4.5 Supports over buildings. Service-drop conductors passing over a and where liable to become charged to more than 300 volts to ground, roof shall be securely supported by substantial structures. shall be isolated or guarded so as not to be exposed to accidental contact Where practicable, such supports shall be independent of the by unauthorized persons. As an alternative to isolation or guarding, building. noncurrent-carrying parts shall be solidly or effectively grounded.  5.3 Where the required clearances cannot be obtained, supply 5. Conductors Passing By or Over Buildings conductors shall be of Grounded Metallic Shield, Jacketed Primary Cables grouped or bundled and supported by grounded messenger 5.1 Minimum Clearances. Unguarded or accessible supply conductors wires. carrying voltages in excess of 300 volts may be run either beside or over buildings. The vertical or horizontal clearance to any V- 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 ≥V 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. 6. Clearance of Service Drops Clearance of line Communication LInes Supply LInes 6.1 Service drop conductors shall not be readily accessible and when not in conductors from - In general On jointly used In general (0 to On jointly used Exceeding 8700 excess of 600 volts, shall conform to the following: poles 8700 volts) poles (0 to 8700 volts, add for each volts) 1000 volts of excess a. Clearances over roof. Conductors shall have a clearance of not less Vertical and lateral conductors of the 75 mm 75 mm 75 mm 75 mm 6.25 mm than 2.5m from the highest point of roofs over which they pass with same circuit the following exceptions: Vertical and lateral 75 mm 75 mm 150 mm 150 mm 10 mm Service Drop Conductor conductors of other ≥ 2.5 m < 600 volts circuits Span and guy wires 75 mm 150 mm 150 mm 150 mm 10 mm Highest point 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 Exception No. 1. Where the voltage between conductors does not exceed 300 Exception No. 2. Service drop conductors of 300 volts or less which do not pass volts and the roof has a slope of not less than 100mm in 300mm, the over other than a maximum of 1.2m of the overhang portion of the roof for the clearance may not be less than 1m. 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. Service Drop Conductor ≥1 m ≤300 volts Highest point ≥500mm Slope ≥ 1:3 Service Drop Conductor ≤ 1.2 m ≤ 300 volts Highest point 6.2 Clearance from the Ground. Conductors shall have a clearance of not less 6.4 Service Drop of communication lines, when crossing a street, shall have a than 3m from the ground or from any platform or projection from which they clearance of not less than 5.5 m from the crown of the street or sidewalk might be reached. over which it passes. Service drop of communication line conductor ≥3m platform ≥ 5.50 m ≥5.50 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 Service Drop of communication lines shall have a minimum clearance of 3m similar locations and shall be run at least 500mm above the top level of a above ground at its point of attachment to the building or pedestal. window or opening. ≥ 500mm window ≥3m ≥3m ≥1m 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 7. Wiring Methods installed above the following: Service entrance conductors extending along the exterior or entering a. Swimming and wading pools and the area extending 3m buildings or other structures shall be installed in rigid steel conduit or outward horizontally from the inside of the walls of the pool. asbestos cement conduit or concrete encased plastic conduit from point of b. Diving Structures service drop to meter socket and from meter socket to the disconnecting c. Observation stands, towers or platforms equipment. However, where the service entrance conductors are protected by approved fuses or breakers at their outer ends (immediately after the ≥3m service drop or lateral) they may be installed in any of the recognized wiring methods. Service 7.1 Abandoned Lines and/or portions of lines no longer required to provide drop shall be removed. conductor 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. Swimming pool 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 8.2 Dry-Type Transformers Installed Indoors. Transformers rated 112-1/2 KVA 8.1 Oil-insulated Transformers Installed Outdoors. Combustible material, or less shall have separation of at least 300mm from combustible material combustible buildings and parts of buildings, fire escapes, door and unless separated there from by a fire-resistant heat-insulating barrier or window openings shall be safeguarded from fires originating in oil- unless of a rating not exceeding 600 volts and completely enclosed except for insulated transformers installed on, attached to, or adjacent to a building ventilating openings. or combustible material. Space separations, fire-resistant barriers and enclosures which confine the oil of a ruptured transformer tank are Combustible Wall recognized safeguards. One or more of these safeguards shall be applied according to the degree of hazard involved in cases where the transformer Dry-type transformer installation presents a fire hazard. Oil enclosures may consist of fire- 112-1/2 Kva or less 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 ≥ 300mm Transformer Trench all around  Transformers of more than 112-1/2 KVA rating shall be installed in a transformer 8.4 Oil-Insulated Transformers Installed Indoors. Oil-insulated transformers shall room of fire-resistant construction unless they are constructed with Class B (80ºC be installed in a vault constructed as specified in this Section except as follows: 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 1. NOT OVER 112-1/2KVA TOTAL CAPACITY. The provisions for transformer there from by a fire-resistant heat-insulating barrier. 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. Transformers rated more than 35,000 volts shall be installed in a vault. 2. NOT OVER 600 VOLTS. A vault is not required provided suitable vault arrangements are made where necessary to prevent a transformer oil fire Combustible ceiling Dry-type transformer igniting other materials, and the total transformer capacity in one location Combustible ≥ 3.70 m Transformer more 112-1/2 Kva or less than 35,000 volts does not exceed 10 KVA in a section of the building classified as Wall combustible, or 75 KVA where the surrounding structures is classified as fire-resistant construction. ≥ 1.85 m > 100mm thick reinforced concrete vault oil insulated transformer < 112-1/2 KVa 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. 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 9. Provisions for Transformer Vaults of fire-resistant construction provided suitable arrangements are made to prevent a transformer oil fire spreading to other combustible material. 9.1 New Building. New buildings requiring an expected load demand of 200KVA or above shall be provided with a transformer vault, except that 4. DETACHED BUILDING. Transformers may be installed in a building which transformers may be mounted on poles or structures within the property if does not conform with the provisions specified in this Code for transformer enough space is available, provided that all clearances required can be vault, provided neither the building nor its contents present fire hazard to obtained and no troublesome contamination on insulators, bushings, etc. any other building or property, and provided the building is used only in can cause hazards and malfunctioning of the equipment. supplying electric service and the interior is accessible only to qualified persons. 150 mm for R.C 8.5 Guarding. Transformers shall be guarded as follows: 200 mm for Brick 300 mm for Load bearing CHB 1. MECHANICAL PROTECTION. Appropriate provisions shall be made Wall: 200 Kva or more to minimize the possibility of damage to transformers from external 20 mm thick plaster causes where the transformers are located exposed to physical 2-1/2 hours fire rating 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 Floor: 100mm thick with the provisions for guarding of live parts in PEC Rule 1056. 2-1/2 hours fire rating 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.  9.4 Doorways. Any doorway leading from the vault into the building shall be protected as follows: 9.2 Location. Transformer and transformer vaults shall be readily accessible to qualified personnel for inspection and maintenance. Vaults shall be located 1. TYPE OF DOOR. Each doorway shall be provided with a tight-fitting where they can be ventilated to the outside air without using flues or ducts door of a type approved for openings in such locations by the authority wherever such an arrangement is practicable. 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 9.3 Walls, Roof and Floor. The walls and roofs of vaults shall consist of reinforced case shall the height be less than 100mm. 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 3. LOCKS. Entrance doors shall be equipped with locks, and doors shall surface of vaults constructed of hollow concrete blocks shall have a coating of be kept locked, access being allowed only to qualified persons. Locks cement or gypsum plaster not less than 20mm thick. The vault shall have a and latches shall be so arranged that the door may be readily and concrete floor not less than 100mm thick. Building walls and floor which meet quickly opened from the inside. 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 10. Ventilation. Ventilation shall be adequate to prevent a transformer temperature resistance of two and one half hours according to the approved Fire Test in excess of the prescribed values. 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. 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 6. DUCTS. Ventilating ducts shall be constructed of fire resistant material. 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 7. DRAINAGE. Where practicable, vaults containing more than 100KVA be provided in one or more openings in or near the roof. 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 3. SIZE. In the case of vaults ventilated to an outdoor area without using ducts or make this impracticable. 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 8. WATER PIPES AND ACCESSORIES. Any pipe or duct system foreign to the KVA of transformer capacity in service, except that the net area shall be not electrical installation should not enter or pass through a transformer vault. less than 0.1 sqm for any capacity under 50 KVA. Where the presence of such foreign system cannot be avoided, appurtenances thereto which require maintenance at regular intervals shall not be located 4. COVERING. Ventilation openings shall be covered with durable gratings, inside the vault. Arrangements shall be made where necessary to avoid screens, or louvers, according to the treatment requirement required in order to possible trouble from compensation, leaks and breaks in such foreign system. avoid unsafe conditions. Piping or other facilities provided for fire protection or for water-cooled transformers are not deemed to be foreign to the electrical installation. 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. 11. Capacitors. 12. Emergency Systems 1. Application. This section applies to installation of capacitors on electric 1. The provisions of this Section shall apply to the installation, operation and circuits in or on buildings. maintenance of circuits, systems and equipment intended to supply Exception No. 1. Capacitors that are components of other apparatus shall illumination and power in the event of failure of the normal supply or in the conform to the requirements for such apparatus. event of accident to elements of a system supplying power and illumination Exception No. 2. Capacitors in hazardous locations shall comply with essential for safety to life and proper where such systems or circuits are additional requirements in PEC Section 400-415. required by the Fire Code, or by any government agency having jurisdiction. 2. Location. An installation of capacitors in which any single unit contains Emergency systems are generally installed in places of assembly where more than three gallons of combustible liquid shall be in a vault conforming artificial illumination is required, such as buildings subject to occupancy by to part C of PEC Section 319. large numbers of persons, hotels, theaters, sports arenas, hospitals and similar institutions. Emergency systems provide power for such functions as 3. Mechanical Protection. Capacitors shall be protected from physical damage refrigeration, operation of mechanical breathing apparatus, ventilation by location or by suitable fences, barriers or other enclosures. essential to maintain life, illumination and power for hospital room, fire alarm systems, fire pumps, industrial processes where current interruption would 4. Cases and Supports. Capacitors shall be protected from physical damage by produce serious hazards, public address systems and other similar functions. location or by suitable fences, barriers or other enclosures. 5. Transformers Used with Capacitors. Transformers which are components of 2. All requirements of this Section shall apply to emergency systems. capacitor installations and are used for the purpose of connecting the capacitor to a power circuit shall be installed in accordance with PEC Section 3. All equipment for use on emergency systems shall be properly approved. 319. The KVA rating shall not be less than 135 per cent of the capacitor rating in Kva. 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 4. Tests and Maintenance emergency power, will be immediately available. The supply system for emergency purposes may be composed one or more of the types of systems a. The authority having jurisdiction shall conduct or witness a test on the covered in Section 12.7 to Section 12.10 of this Rule. Unit equipment in complete system upon completion of installation, and periodically afterwards. accordance with Section 12.21 shall satisfy the applicable requirements of this Section. 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 Consideration must be given to the type of service to be rendered; whether for operating condition. 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 c. Where the battery systems or unit equipment are involved, including from trouble either inside or outside the buildings, as in the case of a hospital. batteries used for starting or ignition in auxiliary engines, the authority having jurisdiction shall require periodic maintenance. Assignment of degree of reliability of the recognized emergency supply system depends upon the careful evaluation of the variables of each particular d. A written record shall be kept of such tests and maintenance. installation. 5. Emergency systems shall have adequate capacity and rating for the emergency 7. A storage battery of suitable rating and capacity shall supply, by means of a operation of all equipment connected to the system. 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 12. Audible and visual signal devices shall be provided, where practicable, for the power, equipped with suitable means for automatically starting the prime mover following purposes: 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 a. To give warning of dearrangement of the emergency or auxiliary source. generator source shall not exceed ten seconds. (See Section 12.4) b. To indicate that the battery or generator set is carrying a load. 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 c. To indicate when a battery charger is properly functioning. simultaneous interruption of power supply arising from an occurrence within the building or group of buildings served. 13. Only appliances and lamps specified as required for emergency use shall be supplied by emergency lighting circuits. 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 14. Emergency illumination shall be provided for all required exit lights and all an occurrence within the building or group of buildings served. other lights specified as necessary for sufficient illumination. Emergency lighting systems should be so designed and installed that the 11. The requirements of Section 12.5 and Section 12.6 also apply to installations failure of any individual lighting element, such as the burning out of a light where the entire electrical load on a service or sub-service is arranged to be bulb, shall not leave any area in total darkness. supplied from a second source. Current supply from a standby power plant shall satisfy the requirements of availability in Section 12.6. 17. Emergency circuit wiring shall be kept entirely independent of all other wiring and 15. Branch circuits intended to supply emergency lighting shall be so installed as to equipment and shall not enter the same raceway, box or cabinet with other wiring provide service immediately when the normal supply for lighting is interrupted. except: Such installations shall provide either one of the following: a. In transfer switches, or b. In exit or emergency lighting fixtures supplied from two (2) sources. a. An emergency lighting supply, independent of the general lighting system with provisions for automatically transferring to the emergency 18. The switches installed in emergency lighting circuits shall be so arranged that only lights by means of devices approved for the purpose upon the event of authorized persons have control of emergency lighting, except: failure of the general lighting system supply. 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 b. Two or more separate and complete systems with independent power only to authorized persons. b. Additional switches which act only to put emergency lights into operation supply, each system providing sufficient current for emergency lighting but not to disconnect them may be permitted. purposes. Unless both systems are used for regular lighting purposes and are both lighted, means shall be provided for automatically Switches connected in series and three- and four-way switches shall not be energizing either system upon failure of the other. Either or both allowed. systems may be part of the general lighting system of the protected occupancy if circuits supplying lights for emergency illumination are 19. All manual switches for controlling emergency circuits shall be located at the most installed in accordance with other Section of this Rule. accessible place to authorized persons responsible for their actuation. In places of assembly, such as theaters, a switch for controlling emergency lighting systems 16. For branch circuits which supply equipment classed as emergency, there shall shall be located in the lobby or at a place conveniently accessible there from. be an emergency supply source to which the load will be transferred In no case shall a control switch for emergency lighting in a theater for motion automatically and immediately upon the failure of the normal supply. 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.  The batteries shall be of suitable rating and capacity to supply and maintain, at not 20. Lights on the exterior of the building which are not required for illumination less than 90 per cent of rated lamp voltage, the total lamp load associated with the when there is sufficient daylight may be controlled by an automatic light unit for a period of at least ½ hour. Storage batteries, whether of the acid or alkali actuated device approved for the purpose. type, shall be designed and constructed to meet the requirements of emergency service. Lead-acid type storage batteries shall have transparent jars. 21. In hospital corridors, switching arrangements to transfer corridor lighting in patient areas of hospitals from overhead fixtures to fixtures designed to provide Unit equipment shall be permanently fixed in place and shall have all wiring to each night lighting maybe permitted, provided that the switching system is so unit installed in accordance with the requirements of any of the wiring methods designed that switches can only select between two sets of fixtures but cannot discussed in Chapter II of the PEC. They shall not be connected by flexible cord. The extinguish both sets at the same time. 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 22. The branch circuits over current devices in emergency circuits shall be fixtures which obtain power from a unit equipment which are not part of the unit accessible to authorized persons only. 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 23. Where permitted by the authority having jurisdiction, in lieu of other methods PEC. specified elsewhere in this Section, individual unit equipment for emergency illumination shall consist of: 13. Effectivity 1. All primary and secondary supply lines already existing shall comply with the a. Battery provisions of this Rule within two (2) years from the effectivity of this Rule. b. Battery charging means, when a storage battery is used 2. Transformers to be installed on, attached to, or in buildings shall comply with the c. One or more lamps, and requirements of this Rule. Transformer installations already existing shall comply with d. A relaying device arranged to energize the lamps automatically upon the requirements within two (2) years from the effectivity of this Rule. failure of the normal supply to the building 3. Non-compliance with the provisions of this Rule shall be subject to the penal provisions in Section 213 of PD 1096. THANK YOU