ELECTRICAL LAYOUT AND ESTIMATE Service Entrance Cable is of the types SE and USE. A single or multi-conductor assembly provided with or without an over all covering, primarily used for service wire. stee! wire at core FIGURE 2-6 SERVICE ENTRANCE CABLE Power and Control Tray Cable (TC). This is a factory assembled two or more insulated conductors with or without associated bare or covered grounding under a metallic sheath This is used for installation in cable trays, raceways, or where it is supported by messenger wire. Flat Cable Assi y of conductors formed integrally with an insulating material web designed specially for field installation in metal surface of raceways: Flat Conductor Cable (FCC) consists of three or more flat copper conductor placed edge to edge separated and enclosed within an insulating assembly, This type of used for general purposes such as: appliance branch ¢ and for individ branch circuits, especially in hard continuous floor surfaces and the like Medi cond) or volts Voltage Cable (MV Cable) is a single or multi- tor solid dielectric insulated cable rated at 2,000 volts igher. This type is used for power system up to 35,000The MV Trade name | Medium Voltage Solid Dielectric. Type letter MV — 75; MV —85; MV — 90. Maximum operating temp 75° C; 85° C, MV 90°C Application : Dry or wet locations, rated at 2,000 volts or higher nt types and characteristics nr Insulation : Thermoplastic or thermosetting 6. Outer covering; Jacket, Sheath or Armor Individually cotor—coded, 600 V. insulated conductors Filler material Binding tape tala ote Type UF — plastic; see NEC article 339 Type TC — plastic; se NEC articie 340 Type ALS —aluminum; see NEC article 331 Type CS—copper; see NEC article 332 FIGURE 2-6 ALL 600 VOLTS JACKETED CABLES Conductor Conductor insulation o insulation Nylon jacket wo) FIGURE 2-7 wire such as Type T and Type TW te No BAW, ‘and stranded from No. 6 AWG and larger. Typical construction of jacke' conductors normally solid throug!“ELECTRICAL LAYOUT AND ESTIMATE 2-3 Ampacity of Electrical Conductors . ‘Ampacity is defined as the ability of the wire or conductor to carry current without overheating. Conductor resistance to current flow, generate not only heat but also contribute to the voltage drop expressed in the following equation: Voltage drop in wire = Circuit current x Resistance of wire Power loss in wire = Circuit current x Voltage drop P = Ix(IxR) P=I17?R Power Loss is equal to the components resistance times the current squared. This power loss being converted into heat, must be dissipated. A small wire diameter can safely carry more current in proportion to its weight. The use of copper wire is most preferred. Section 3.1.2.1 of the National Electrical Code provides that: “Conductor size and rating shall have sufficient ampacity to carry load. They shall have adequate mechanical strength and shall not be less than the rating of the branch circuit and not less than the maximum load to be served.” Conductors Ampacity is determined by the maximum operating temperature that its insulation can withstand con- tinuously without heating. Current flow and conductor’s resis- tance normally generates heat. Thus, the Operating temperature depends upon the amount of current flow, » environment. Environment refers to either enclosed or open condition on which the wire is placed The Ampacity or ability of the conductor to carry lead increases as the sizes of conductor increases. If more than 3 conductors are inserted into a conduit, the temperature als? and it requires derating of 7 8 of the conductors ampacttY as prescribed in Tables 2-5, 2 MGLOTS | SINE increas 6 and 2-7CONDUCTORS AND WIRING ACCESSORIES TABLE 2-5 ALLOWABLE AMPACITIES OF INSULATED COPPPER CONDUCTORS NOT MORE THAN 3 WIRES IN RACEWAY 60°C (140° F) ‘Temperature Ratings of ConductorABLE 2-7 TYPICAL AMBIENT TEMPERATURE Minimum rating required Location Temperature Conductor insulation ‘Well ventilated normally heated building 30°C See note below Building with such major heat sources as power 40°C SG stations or industrial processes Poorly ventilated spaces as°c such as attics Furnaces and boiler room | Min. 40° C 7c Max. 60° C 90°C Outdoor in shade in air 40°C eS In thermal insulation 45°C fae Direct solar exposure 45°C 7s°c Place above 60°C 110°C Note: 60°C up to No. 8 AWG copper wire and 75° C for bigger than No. 8 SOURCE: The National Electrical Code Derating of Conductors Ampacity ~ mcans that, the full amount of allowable ampacity, is reduced to a certain percent- age due to the environmental condition it is exposed of and the number of wires placed imside the conduit. The current rating of wire in a free air environment is higher than those placed inside the conduit. Concomitant with this, if the ambient tem perature is above 30° C, the allowable ampacity will be fe duced by the factors given in Table 2-6CONDUCTORS AND WIRING ACCESSORIES 2-4 Raceway Raceways are channels or wiring accessories so designed for holding wires, cables or busbars that are either made of metal, plastic, or any insulating mediums. The common types of raceways for houschold wirng 1, The conduits 2. The connectors and other accessories TABLE 2-8 CHARACTERISTICS OF RACEWAYSNae ee 14 | b | 44 b | 56 3000 ey B27 bel Boe) ad fo: |b. | 20 b | 20 14 | 17 | 28 17 | 68 4000 12 1s 24 15 s3 10} 11 | 20 | 1 | 41 S71 4a 77] 2 — +— 14 | 61 | 97 | 61 | 234 12 | 54 | 82 54 184 6000 10 | 38 | 6s | 38 | 141 8 27 | 41 27 27 Eo 6 | 20] 25 | 20 | 38 a8CONDUCTORS AND WIRING ACCESSORIES Other Types of Raceways Aside from the conduits and connectors, there are other type of raceways such as Conduit coupling, elbows and other fittings Conduit supports, such as clamps, hanger, etc Cable trays, cable bus, etc Metal raceways Nonmetal raceways and other waunesists pass andthe ike The Purpose of Electrical Conduits are: 1. To provide a means for the running wires from one point to another. To physically protect the wires. To provide a grounded enclosure. To protect the surroundings against the effect of fault in the writing. 5. To protect the wiring system from damage by the building and the occupants. 6. To protect the building and the occupants from damage by the clectric system. Connector ‘Connector is a metal sleeve usually made of coppeT that #§ slipped over and secured to the butted ends of conductors if making a joint. Connector is otherwise called splicing sleeveCONDUCTORS AND WIRING ACCESSORIES 750,000 32" FIGURE 2-9 STANDARD SIZE OF CONDUIT FOR INSTALLATION OF WIRE CABLE 41fy 2 OC ot 4 “o* Clamp Malleable tron re Manger rod R.H, thread & : - LH thread paren Forged Steel Turnbuckle 1 Beam clamp Side Beam Clamp FIGURE 2-10 OTHER TYPES OF RACEWAYS = QS «ap Compression Type Rain Tight Coupling Compression Type ain Tight Connection 2» = © «6 tome saiocssdien atl 8 09 Coup Inautated Connector insisted FIGURE 2-11 VARIOUS TYPES OF EMT CONNECTORS 42CONDUCTORS AND WIKING ACCESSORIES 7 in One Conduit (mm) Gude! t 2 ¢ «¢ € € fie TABLE 2-9 MAXIMUM NUMBI mn OV Wi Number of Wir IN A CONDULT rr) 3s 8 #9 2 20 S) 2 ee 2 @ 19 90 $9 30 3S (aber cee 10 19 20 20 2 26° 26 Seb oak ee 8 1% 20 26 3 28 $8) a2 Dasa 6 0 © 82 88 Se 8. SO ee ee s 20-92 (88 a ee ee 4 20 32 2 “6 650 60 % 50 os 3 20 #32 32 38 6606 60 |} OO Cee ae 2 20 320 (38 8 0s 1 20 38 38 8 8 Of & 75 78 ° 2 98 6 © @ 68 7 75 75 00 2 60 O° On re es 000 28 80) 6600 O37 7S e000 32 SO) 63} 75 7S 8 tO . 20000 2 50 63 63 «76 7 88 8B 100 22500 32 68. 9 08S) hee 250000 32 63 63 7m 75 88 300000 32 63 7 75 «88 88 350000 32 63 «75 88 88 100 . 400000 32 75 75 88 100 100 e 450000 a ce} 7 88 6100 413 500000 38 7S ci] ge 100 «113 550000 3 = 88 ‘600000 50 5 88 650000, SO 88 88 700000 so 88 8BA Convenience outlet or attachment cap is a device that by insertion into a receptacle establishes connection between the conductor of the flexible cord and the conductors connected permanently to the receptacle. @ oo 8) ne normal Tepe 15 am Fa 2pole2wire one locking device — Sinale tvoe grounding: - FIGURE 2-12 VARIOUS CONVENIENCE OUTLETr CONDUCTORS AND WIRING ACCESSORIES Wall Outlet. The common Wall Outlet is called Convenience Outlet And to call it: wall plug is not correct & plug is another name for the attachment cap on the wire coming from a device such as lamps or appliancescal yy nc sir stiches ond fencdon as outlets. This is an important thing to clarify specially en payment is to be made from a contract based on the number of outlets. An Outlet on the other hand. refers only to the box itself It does not include the items. The receptacle device is not an electrical load but rather an extension of the box wiring. The outlet is separate from the load device even if it is included as \ part of the device. The Pull Box is a box with a blank cover that is inserted in one or more runs or raceways to facilitate pulling-in the ; conductors. It may also serve to distribute the conductors. Receptacles are contact device installed at the outlet for the connection of a single attachment plug. Receptacles are : included in the general. classification of wiring devices. It includes all receptacles and their matching cap (plug), wall switches, small dimmers, and outlet box mounted lights Receptacle is defined by the National Electrical Code as: “4 contact device installed at the outlet for the connection of a single attachment plug.” Any number of receptacles mounted together in one oF more coupled boxes is classified as ome outlet, The lower the number of outlets the lower is the cost. A circuit with 6 duplex receptacles individually mounted ts normally more than twice the cost of the same 6 receptacles installed in two outlets group of three gang each. Receptacles are descmbed and according to the pole of wires ®CONDUCTORS AND WIRING ACCESSORIES Mounting the Receptacles 1. A wall convenience receptacle is vertically mounted between 30 to 45 centimeters above the finished floor line. 2. In industrial areas, shops, workroom and the like, the mounting height is from 105 to 110 centimeters. This is above the table height horizontally mounted so that the cords will not hang on top of each other. 3. The GFI or GFCI (ground fault circuit interceptor) re- ceptacle should be installed on locations where sensi- tivity to electric shock is high such as in wet areas. Switch A Switch is a device that open or closed the circuitry in an electric circuit. Special actuator plate ‘Specification Grade switches 19, 20 and 3G-ampere Maintained contact 15 and 20 i ampere bg ew (Double throw, center oft) aTNNN jaaRas RR_ZRN RRS The General use switch is intended for use in the general distribution and branch circuit rated in amperes, It is capable of interrupting the rated current at a rated voltage The General use snap switch is a form of general use switch installed in flush device boxes or an outlet box cover The Isolating switch is a switch intended for isolating an electric circuit from the source of power 48CHAPTER THE BRANCH CIRCUIT 3-1 Introduction Electric Circuit refers to the complete path traversed by an electric current. In short, electric circuit is the entire house wiring installation. Branch Circuit is defined by the National Electrical Code (NEC) as: “the circuit conductors between the final over cur- rent protective device and the outlets.” Meaning, the branch circuit is only the wiring installed between the circuit over cur- rent protective device i.e. fuse or circuit breaker, and the out- lets. a ee In practice however, it is a common knowledge that the branch circuit comprises the following: 5 1. The source of voltage 2. The wiring and 3. The loadFlexibility of the Circuit means that the installation can accommodate all probable pattern arrangements and location of the loads for expansion, or future development. Reliability and Efficiency of Service means to have a continuous service and supply of power that are all dependent on the wiring system. Reliability of electric power in a facility is determined by two factors: 1. The utility service 2. Building electric system Safety means that independent service can be used in lieu of emergency equipment as backup for normal services. For reliability of the circuitry, the following principles should be considered. 1. To provide double emergenc: 2 c lected weak points inthe system. tupment St 8 2. That the electrical service and the building distribution eee en eo oui so that the power can reach the 3. Critical loads within the facility must be pinpointed 1 determine the best way to serve them by providing a re liable power either from the outside source, or bY standby power packaye for them, i 50THE BRANCH CIRCUIT 4. The system design must readily detect any equipment failure and to be corrected automatically Der oe cir fates a ee costs. These two cost-factors stand in inverse one another. Over design is as bad as under design. i The Effect of Acquiring Low Cost Equipment 1. High energy cost 2. Higher maintenance cost 3. Shorter life Energy Consideration is a complex one considering the following factors: Energy laws and codes Budget Energy conservation technique Energy control eee Space Allocation — must consider the following: Easy maintenance Ventilation Expandability Limitation of access pee Protective device Generally 15, 20 amperes_as follows: - General purpose branch circuit supplies tacles. Z pliance branch circuit supplies outlets intended Ae feeding appliances. Fixed lighting however, is not supplied. Generally 20 amperes FIGURE 3-3 APPLIANCE BRANCH CIRCUIT 3. Individual branch circuit is designed to supply a sin- gle specific item. ‘Size required for item fed _ Single ttem FIGURE 3.4 INDIVIDUAL BRANCH CIRCUITTHE BRANCH COU 3.2 Civcuiting Guidelines There are many ways of doing the eireuitey but there is ne optimum or perfect way of doing it, However, there are certain miles and guidelines promulgated by the National Kheetrteal Code (NEC) for flexibility, economical and convenient way of installing a eirouitry 1 The Code requires sufficient circuitry to supply resin dential load of 30 watts per square meter in buildings excluding porches, garages and basements. 2. The requirement of 30 watts per square meter is up to 80 sq. m. for a 20 amperes circuit (2,400 watts) or 60 square meters for 15 amperes circuit (1,800 watts), 3. Good practice suggests that the load should not exceed 1,600 watts for a 20 amperes circuit and 1,200 watts for a 15 amperes circuit. Thus a) Observe a minimum load of 1,200 watts on a 15 amperes circuit with a maximum area of 40. square meters. b) A maximum load of 1,600 watts on a 20 am- peres circuit with a maximum area of 53 square meters, 4. The Code requires a minimum of 20 amperes appli~ ance branch circuit to feed all small appliance outlets in the kitchen, pantry, dining and family room, iss The general purpose branch Se cre ciee ae ef amperes circuit, wired with No. 1: being, th minimum size of conductor wire required for all venience outlet. Circuit load on a the values given"ELECTRICAL LAYOUT AND ESTIMATE a) For 15 amp circuit: a5 Sues b) For 20 amp circuit: ee 8 outlets 8. Convenience receptacles should be planned Properly, so that in case of failure by any one of the circuitry, the entire area will not be deprived of power supply. In terms of reliability of service, each area should be pro- vided alternately with different circuits. 9. All kitchen outlets should be fed from at least two of these circuits. 10. The Code further stipulated that; “all receptacles are potential appliance outlet and at least two circuits ‘shall be supplied to serve them.” 11. Certain outlets in the room shouid be designed as ap- pliance outlet like: a) All kitchen receptacles b) Dining room receptacles c) One in the living room 12. The Code requires that, “at least one 20 amperes cir- cuit supply the laundry outlets.” 13. If air conditioner is anticipated, provide a separate cir- cuit for this particular appliance TABLE 3-1 BRANCH CIRCUIT CAPACITY - ELECTRIC HEAT Maximum Watts Circuit Breaker Size 120 volts 240 volts 45 amp. 1440 2880 20 amp. 1920 3840 30 amp. 2880 5760 54THE BRANCH Crmcurr TABLE 3-7 BRANCH CIRCUIT REQUIREMENTS 16 amp | 20 amp | 30 w Maximum size of conductor Not4 2 Minimum size taps No14 4 Over current device rating | 15 amp 20 %» Lamp holders permitted Anytype| Any type] H.Outy | H.Duty Receptacte rating permitted| 15 amp| 15-20 20 40-60 | 50 Maximum load 15amp| 20 30. 40. 50 Other Good Practices in Circuiting 1. Lighting and receptacles should not be combined in a single circuit. 2. Avoid connecting all building ieee on a single cir- cuit 3. Lighting and receptacles should be supplied with cur- rent from at least two circuits so that, if a single line is out, the entire area is not deprived of power. 4. Do not allow combination switch and receptacle out- lets, 5. Provide at least one receptacle in the bathroom, and one outside the house. Both must be Ground Fault Cir- cuit Interrupter (GFCI) type. Provide switch control for switch is a nuisance. Convenience outlet though counted as part of the gen- eral lighting load shall be limited to 6 convenience outlets on a 15. amperes cicant and Sfoonyeniensercut lets on a 20 BDO circuit. closet lights. Pull chainAs a Rule. branch circuit should be protected fro current. Hens; an over all current protective devices installed in all branch circuitries. The function of the over-current protective devices open the circuit (disconnect the line) when the current capacity of the equipment being protected is exceeded. circuit protective device represents the source of voltage. It, always connected at its hot line end to the voltage source jts load end to the circuit wiring. Apparently, it becomes source of voltage. The Panel Board where:n the over current protective vice is a part, the busbars become the source of voltage as look upstream from the over current devices. The Nation Electrical Code also defines the branch circuit as “shat portit of the circuit beyond the over current device. oa Causes of Over Current There are two principal causes of over current 1. Overload in the equipment or conductors 2. Short circuit or ground fault Both were the results of excessive current flow in the cuit. The primary function of the over-current devices # protect the branch circuit and the load device against exce current supply. However, regardless whether the excess rent is being caused by an equipment problem of ove! or by a circuit problem such as un-intentional ground fal protective devices has but one purpose - to interrupt t in case there is an excess current flow in the circuit. _ When the over current protective devices senses sive flow of current, it automatically open the circuit OF 56‘THE BRANCH CIRCUIT cut off the line to prevent the excessive flow of current in cre- ating damages to the circuit or to the equipment. The over cur- rent device automatically opens the line to release the exces- sive current. The action of the over current protective device is called “Clearing” because it clears the circuit of the fault or over current load. It therefore acts in the same manner as the mechanical device to relieve the machine from excessive pres- sure The over current protective devices are installed in circuits to protect the following: The wiring The transformer The lights Appliances and other equipments Beye On the Protection of Conductors, the National Electrical Code provides that: “Conductors shall be protected against over current in accordance with their ampacities.” By definition, Over Current is any current in excess of the rated capacity of the equipment or the rated ampacity of the conductor. It was clear that both the equipment and the wire installation shall be protected from the over current flow. Electrical equipment has its own rated ampacity. Simi- larly, electrical conductors have also their respective allowable ampacity. Thus, any load in excess of their rated or allowable ampacity, could damage the circuit or the equipment Application of Over-current Protection is also Governed by the Following Rules: 1. That the over-current protection devices should be in- stalled on the line or supply side of the equipment be- ing protected. : 2. The over-current protective devices shall be placed in all underground conductors of the protected circuits.OUT AND ESTIMATE ELECTRICAL LAY 3. All equipment should be protected. in accordance with : ing capacity. 2 ifs current catryine Oe protective devices should be -current ; os ee caecubled and protected from physical dame ages and away from easily ignited materials. ae 5. Conductors size should not be reduced in a circuit or tap unless the smallest wire 1S protected by the circuit over current devices. Neo Taps may be made if smaller con- ductor is protected by main feeder protection (100 amp. circuit breaker for No.2 wire) 100 amp. No.2 RHW (115 amp.) Taps up to 7 m. long is allowed if tap conductors has minimum 1/3 ampacity of main and terminates in a single circuit breaker or set of 1/3 capacity = 130 = 45 amp fuses which limits the current on 3 the tap to the wire capacity. 40 a. fuse limits current on 45 amp capacity wire. 7.5 m. Maximum Taps up to 3 m. long are allowed Provided they have suflicient capa city for the circuit they feed, say No. 10 RHW if the wiring feeds 2-15 amp. cil- in conduit cuits, it must have 30 amp capa- city and should be No. 10 AWG, 2-15 amp circuit RHW wire or equal rating. 3 m. maximum Main feeder No.1/0 RHW Taps of any length may be made if 130 amp capacity conductor is protected at the tap point by and approximately fie TT overe em Teurrent device. Feeder FIGURE 3-5 PERMISSIBLE TAP ARRANGEMENTS 5BTHE BRANCH CIRCUIT 3-4 Fuse, Breaker and Panel Board Fuse is defined as; an over all current protective device with a circuit opening fusible element which opens (break) when there is an over current in the circuit. ‘The Fuse is a one time protective device to be replaced after the fault is cleared. It is the simplest and most common type of circuit protective device used in most house wiring installa- tions. It is available in hundred design ratings and shapes but basically, the same in functions Generally, fuse consist of a fusible link or wire that easily melt at low temperature classified into two types 1. The Cartridge type which is enclosed in an insulating fiber tube and 2. The Plug Fuse type enclosed in a porcelain cap. TABLE 3-3 FUSE RATING AND CONSTRUCTION Current Ratings 0 to 10 15, 20, 25 to 30 mas. 150 v. to ground 0 to 10 35, 40, 45, 50 to 60 70, 80, 90,100, 110, 125, 150 175, 200, 225, 250, 300, 350 400, 450, 500, 600 800, 1000, 1200, 1600, 2000 2500, 3000, 4000, 5000, 6000 Circuit Breaker The Circuit Breaker is an over-curn designed to function as a switch. Basi: Cartridge type with ferrules single and dual element 250 and 600 volts Cartridge type, knife blade contacts: 250 and 600 volts Cartridge type bolted knife blade contacts; 600 volts ent protective device ically, a circuit breaker is 59i equipped with an automatic tripping device to Protect tt pranch circuit from overload and ground fault. Circuit breaker can be manually tripped, so that, in many cases, it also acts ag _ circuit switch. 7 Trip or Tripping refers to the cutting-off or disconnection of the current supply. Advantages of Circuit Breaker Over the Fuse 1. The circuit breaker act as switch aside from its being an over current protective device. 2. Unlike the fuse that has to be ciscarded after it was busted due to an over current flow, the circuit breaker trips off automatically and after correcting the fault, it is again readily available for switch on. (b) Single Element Knife (a) Common Household Piug Blade Fuse Thermal cutout element Ferule contact Short circhit fuse link Knife blade contact Dual element - time delay fuse with Edison base, ferrule contag® and knife blade contacts respectively FIGURE 3-5 STANDARD TYPE OF FUSE Circuit breaker can be multiple pole installed with 12 3 poles which will simultaneously protect and ;THE BRANCH CIRCUIT one to three lines. The fuse on the other hand, is a single pole, installed on a single wire that could only protect a single electric line. The circuit breaker position is easier to detect. It could be closed, tripped, or open right at the handle. On the contrary, the busted fuse could not be detected easily be- cause the melted fusible element is inside the fuse cas- ing The circuit breaker can be manually tripped so that in many Cases, it also acts as the circuit switch Conventisnat i caa Ger breaker ie breaker wired into wired toto preree Dane! tox l 1 fie } (deer 1k | fer : 7A f fl Load nowe: wire leek) Equipment toed ground Coiled white oe wire connects to wl Neutral bus Pere! neutral Equipment ground bus All connections to the CBS circuit breaker are si {0 those of conventional breakers except for the addition of ¥ neutral connection. FIGURE 3-7 BRANCH CIRCUIT PROTECTION |