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Transcript of 1 Electrical Systems Final
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ELECTRICAL SYSTEMS
1.1 DEFINITION OF ELECTRICITY
a form of energy generated byfriction, induction or chemicalchange, having magnetic, chemicaland radiant effect.
the motion of free electrons througha solid conductor.
1.2 SOURCES OF ELECTRICITY
STORAGE BATTERIES
GENERATORS
1. GENERAL
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STORAGE BATTERIES
are used to supply emergencylighting circuits for hallways,
stairways, exits and to energizepolice and fire alarm systemsand certain types of signalsystems.
GENERATORS
for generating electric current
Alternating Current Generators orAlternators The bulk of electrical energyutilized today is in the form of alternatingcurrent, including energy for power and
lighting.
Direct Current Generators Thesefurnish electrical energy for elevators,escalators, intercommunicating telephonesystems, control of signal systems, andclock systems.
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1.3 OTHER DYNAMO ELECTRICMACHINES
MOTORSfor convertingelectrical energy to mechanicalenergy.
TRANSFORMERSforconverting one voltage to
another, from lower to higheror from higher to lower
ROTARY CONVERTERSfor changing alternatingcurrent to direct current andvice versa.
1.4 TYPES OF CURRENT
ALTERNATING CURRENT acurrent which is periodicallyvarying in time rate and indirection. It rises from zero tomaximum, falls to zero, reversesits direction and again returns tozero.
DIRECT CURRENT a currentwhich flows at a constant time rateand in the same direction.
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UNIT OF QUANTITY
1.5 UNITS OF ELECTRICITY
COULOMB a coulomb of electricitycomprises approximately 6.25 x 10 18electrons.
AMPERE An ampere of currentrepresents a rate of flow of onecoulomb or 6.25 x 10 18electrons/second through a givencross section.
UNIT OF ELECTRIC POTENTIAL
VOLT is the electromotive forceor potential difference between twopoints in an electric field which willmove a charge of one coulombbetween these points.
UNIT OF RESISTANCE
OHM The resistance which willallow one ampere of current to flowwhen one volt is impressed upon it.
UNIT OF ELECTRIC POWER
WATT the unit of electricpower or the rate of doingelectrical work.
UNIT OF ENERGY
WATT-HOURS the unit ofenergy or the capacity for doingwork.
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1.6 OHMS LAW
I (amp) = V(Volts) /R(Ohms)
The current, I, that will flow in ad-c circuit is directly proportional tothe voltage ,V, and inverselyproportional to the resistance , R,of the circuit.
is the effective utilization of availableenergy by reducing peak loads andlowering demand charge. The controldevices and systems are referred to asload shedding control, peak demandcontrol, peak load regulation, and poweruse control.
LOAD SCHEDULING AND DUTY-CYCLE CONTROL the installationselectric loads are analyzed and scheduledto restrict demand by shifting large loads
to off-peak hours and controlled to avoidcoincident operation.
DEMAND METERING ALARM inconjunction with a duty cycle controller,demand is continuously metered and analarm is set on when a predetermineddemand level is exceeded.
1.7 ELECTRIC LOAD CONTROL
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AUTOMATIC INSTANTANEOUSDEMAND CONTROL also called ratecontrol, it is an automated version of thedemand metering alarm system, where it
automatically disconnects or reconnects loadsas required.
IDEALCURVE CONTROL This controlleroperates by comparing the actual rate ofenergy usage to the ideal rate, and controlsKW demand by controlling the total energyused within a metering interval.
FORECASTING SYSTEMS arecomputerized systems which continuouslyforecast the amount of energy remaining inthe demand interval, then examine the statusand priority of each of the connected loadsand decide on the proper course of action.
WATTMETER
VOLTAGELEADS
LOAD
WM
CURRENTLEADS
POWERSOURCE
1.8 MEASURING ELECTRIC CONSUMPTION
KWH METERS Tomeasure energy, thefactor of time isintroduced, such that;energy = power xtime. A-C electricmeters are basicallysmall motors, whose
speed is proportionalto the power beingused. The number ofrotations is counted onthe dials which arecalibrated directly inkilowatt-hours.
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2. BUILDING ELECTRICAL SYSTEMS
2.1 BRANCH CIRCUITS
An electrical circuit may be defined as a
complete conducting path carrying currentfrom a source of electricity to and throughsome electrical device or load and back to thesource. The two wire circuit, which is themost elementary of all wiring systems,consists of a live wire carrying the current tothe various power consuming devices in thecircuit and a neutral or grounded wire whichis the return wire carrying the circuit back tothe source of supply.
SERIES CIRCUIT
PARALLEL CIRCUIT
SERIES CIRCUITis one in which thecomponents are connected in tandem. Allseparate loads of the circuit carry thesame equal current and the totalresistance, R, is the sum of theresistances around the circuit.
PARALLEL CIRCUIT (or MultipleCircuit) is one in which the
components or loads are so arrangedthat the current divides between them.Each outlet has a live wire connected tothe current carrying wire of the circuitand also a neutral wire or grounded wireconnected to the return wire of thecircuit. With this system, the total currentflowing through the circuit is the sum ofthe current flowing through each outlet.
R = R1 + R2 + R3 + R4 + R5
10 ampR 1 R 2
10 amp
ELECSOURCE
CIRCUIT IN SERIES
R 5 R 410 amp
10 amp
R 3
ELECTRICALSOURCE
CIRCUIT IN PARALLEL
3 amp
1 amp1 amp1 amp+
R 1 R 2 R 3
1R =
1/R1 + 1/R2 + 1/R3
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CLASSIFICATIONS OF BRANCH CIRCUITS
General Purpose Branch Circuit -supplies outlets for lighting and
appliances, including conveniencereceptacles.
Appliance Branch Circuit - suppliesoutlets intended for feeding appliances.Fixed lighting is not supplied.
Individual Branch Circuit - isdesigned to supply a single specific item,such as a motor load or a unit air-conditioner.
SIZE REQUIREDFOR ITEM FED
15, 20, 30,or 50A A A
LTG AGENERALLY
15, 20A
SINGLE ITEM
Branch Circuit
The portion of an electricalsystem extending from the final
overcurrent device protecting a
circuit to the outlets served by
the circuit
Distribution PanelA panel for distributing
power to other panels or to
motors and other heavy
power-consuming loads.
Controls, distributes and
protects a number of similar
branch circuits in an
electrical system
Low-Voltage
Of or pertaining to a circuit in which alternating
current below 50 volts is supplied by a step-down
transformer form the normal line voltage used in
residential systems to control doorbells,
intercoms, heating and cooling systems and
remote lighting fixtures. Low-voltage circuits do
not require a protective raceway
General Purpose Circuit
A branch circuit that supplies
current in a number of outlets for
lighting and appliances
Appliance Circuit
A branch circuit that supplies
current in one or more outlets
specifically intended for
appliances
Individual Circuit
A branch circuit that supplies
current only to a single piece of
electrical equipment
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GENERAL CIRCUITING GUIDELINES
1. General: Branch circuits shall besufficient to supply a load of 30watts per square meter (3 watts persquare foot) in buildings excludingporches, garages and basements.
2. In all but the smallest installations,connect lighting, conveniencereceptacles, and appliances inseparate circuits. The Code requires aminimum of 2 - 20 amperesappliance branch circuit to feed allsmall appliance outlets in the kitchen,pantry, dining and family room.
DINE
KIT
Ref
C2
Range
C1C4
C3
C3
C320 amp
20
amp
3. Convenience receptacles in an areashall be wired to at least twodifferent circuits so that in case offailure in any one of the circuits, theentire area will not be deprived ofpower.
4. General purpose branch circuits shallbe rated at 20 amperes wired withNo. 12 AWG minimum. Switch legs
may be No. 14 AWG if the lightingload permits.
5. Limit the circuit load for lighting andsmall appliances on 15 amp and 20amp circuit loads and on 15 and 20amp overcurrent devices respectively.
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2.2 SINGLE PHASE ELECTRICAL SYSTEMS
Two-Wire Single Phase DC or AC
Three-Wire Single Phase DC(EDISON SYSTEM)
Three-Wire Single Phase AC
For homes and small commercial buildings
SWITCH FUSE
220 V
110 V
110 V
A single phase electrical system caneither be 2-wire or 3-wire andcomposes two hot legs and a neutralwire.
2.2 THREE PHASE ELECTRICAL SYSTEMS
Three-Wire Three Phase AC
Four-Wire Three-Phase AC
For industries and large commercial buildings
A-B 220V
B-C 220V
A-C 220V
A B C
A
B
C
220V
N B CA
220V
220V
110V
110V
110V
MOTOR
The Three Phase AC electricity is a TripleCircuit. The lighting and outlet loads areconnected between any phase leg and aneutral line. While machineries and otherbigger loads are connected to the phase legonly.
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2.3 COMPONENTS OF THE BUILDING ELECTRICAL SYSTEM
Substation
An auxiliary power station
where electrical current is
converted or where voltage
is stepped up or down
Service
The supplying of utilities required
or demanded by the public
Line Drop
The decrease in voltage between
two points on a power line,
usually caused by resistance or
leakage along the line
Service Entrance Conductor
The portion of a service conductor extending
from a service drop or service lateral to the
service equipment of a building
Watt-Hour Meter
A meter for measuring and recording the
quantity of electric power consumed with
respect to time
Transformer Vault
A fire-rated room housing
a transformer and
auxiliary equipment for a
large building
Switchgear Room
Contains the service
equipment for a large
building
Service Equipment
Equipment necessary for
controlling, metering and
protecting the electric
power supply to a builidngStandby Generator
For providing emergency power
during a power outage.
Uninterruptible Power Supply
An emergency system designed
to provide pwer automatically and
instantaneously
Switchboard
One or a group of panels on
which are mounted switches,
overcurrent devices,
metering instruments and
buses
Unit Substation
A freestanding enclosure
housing a disconnect
switch, a step-down
transformer and
switchgear
Feeder
Any of the conductors
extending from the
service equipment to
various distribution
points in a building
Service Drop
The overhead portion of service
conductors extending from the
nearest utility pole to a building
Service Lateral
The underground portion of service
conductors extending from a main
power line or transformer to a
building
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Lightning Rod
Any of several conducting rods installed at the
top of a structure and grounded to divert
lightning away from the structure. Also called air
terminal
Lightning Arrester
A device for protecting electric equipment from
damage by lightning or other high-voltage
currents, using spark gaps to carry the current
to the ground without passing through the
device
Spark Gap
A space between two terminals or electrodes
across which a discharge of electricity may pass
at a prescribed voltage
Servcie Drop
The overhead portion of service conductors extending
from the nearest utility pole to a building
Servcie Lateral
The underground portion of servi ce conductors extending
from a main power line or transformer to a building
Service Conductors extend from a main power
line or transformer to the serv ice equipment of a
building
Servcie Entrance Conductor
The portion of a service conductor extending from a servi ce
drop or service lateral to the service equipment of a building
Watt-Hour Meter
Measures and records the quantity of electric power
consumed with respect to time. Supplied by the public utility,
it is always placed ahead of the main disconnect switch so
that it cannot be disconnected
For multiple-occupancy buildings, banks of meters are
installed so that each unit can be metered
independently
Grounding Rod or ElectrodeIs firm ly embedded in the earth to establish a ground
connection
To panelboards
Direct burial cable may be used for
residential service connections
A transformer is used by medium-sized and large buildings to step
down from a high supply voltage to the service voltage. To
reduce costs, maintenance and noise and heat problems, a
transformer may be placed on an outdoor pad. If located within a
building, oil-filled transformers require a well-ventilated, fire-rated
vault with two exits and located on an exterior wall adjacent to the
switchgear room. Dry-type transformers used in small- and
medium-sized buildings may be replaced together with a
disconnect switch and switchgear in a unit substation
The service switch is the main
disconnect for the entire electrical
system of a buil ding, except for any
emergency power systems.
The service equipment includes a main
disconnect switch and secondary
switches, fuses and circuit breakers for
controlling and protecting the electric
power supply to a building. It is located
in a switchgear room near the entrance
of the service conductors
The main switchboard is a panel on
which are mounted switches,
overcurrent devices, metering
instruments and busbars for controlling,
distributing and protecting a number of
electric circuits
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SERVICE ENTRANCEthe point ofdelivery of electricity to a building by apublic utility company.
MAIN SWITCHBOARD The serviceentrance conductors in the form of busbars terminates in the main switchboardand connects to the distribution panel
boards by means of feeder circuitsprotected by circuit breakers. The mainswitchboard serves for the control,protection and metering of the mainfeeders.
FEEDER CIRCUITSA feeder circuitis a set of conductors which extendsfrom the main switchboard to adistributing center (panel board) with noother circuits connected to it betweenthe source and the distributing center.
SUB-FEEDER CIRCUITS are line
extensions of a feeder, fed through apanel board or cut-out, or from onedistributing center to another and havingno other circuit connected to it betweenthe two distributing centers. A sub-feederserves to distribute power from the mainfeeders to smaller local panel boards,called sub-panel boards.
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PANEL BOARDS AND SUB-PANELBOARDS (also called CUT-OUTS) Theseserve to control and protect the subfeeders and branch circuits.
UTILIZATION EQUIPMENT These
are the lighting, power and motor loadsand wiring devices which are directlyhandled and utilized by users.
BRANCH CIRCUITS These aresmall capacity conductors which deliver
energy to lamps, motors and other loadswithin the circuit.
Service Switch
The main disconnect for the entire
electrical system of a building
except for any emergency power
systems
Panel
A board on which are mounted
the switches, fuses and circuit
breakers for controlling and
protecting a number of similar
branch circuits installed in a
cabinet and accessible from
the front only. Also called a
panelboard.
Bus
A heavy conductor, usually in the form of asolid copper bar, used for collecting, carrying
and distributing large electric currents. Also
called a busbar
Grounded Conductor
Any conductor of an electrical system
intentionally connected to a ground
connection
Grounding Electrode
A conductor, as a metal ground rod,
ground plate or cold-water pipe, firmly
embedded in the earth to establish a
gorund connection
Fuse
A device containing a strip or
wire of fusible metal that meltsunder the heat produced by
excess current thereby
interrupting the circuit
Circuit Breaker
A switch that automatically interrupts an electric
circuit to prevent excess current from damaging
apparatus in the circuit or from causing a fire. A
circuit breaker may be reclosed and reused withoutreplacement of any components. Also called a
breaker.
Ground Wire
A conductor connecting
electric equipment or a
circuit to a ground
connection. Also called a
grounding conductor
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2.4 ILLUSTRATING THE COMPONENTS OF THE BUILDINGELECTRICAL SYSTEM
BLOCK DIAGRAMA horizontal single linediagram of the buildingselectrical system from theincoming service to theutilization items at the endof the system where themajor electricalcomponents are shown asblocks or rectangles.
RISERDIAGRAMIs a vertical linediagram of themajor electricalcomponents ofthe buildingselectrical system
presentedshowing thespatial relationsbetweencomponents.
ELEVATORS
PPMR
MACHINEROOM
5A
LP
4A
3A
2A
1A LP
LOBBY
1B
2B
3B
4B
5B
LEFTRISER
5C
4C
3C
2C
1C
ROOF
CENTRAL RISER SHAFT
RIGHT RISER
M.C.C.
MACHINE ROOM
FA
LPSE
FIRE ALARMPANELSTAIR AND EXITPANEL
M METERING
SPARE
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2.5 EMERGENCY ELECTRIC SUPPLYSYSTEM
Emergency Systems provide electricpower and illumination essentially for lifesafety and protection of property duringan emergency, such as, electricity for exitlighting, elevators, fire alarm systems,fire pumps and the like.
Standby Systems provide power toselected loads not directly involved with
life safety, such as, water and sewagetreatment plants and industrial machinesfor manufacturing processes.
EMERGENCY POWER EQUIPMENT
Battery Equipment Central storagebatteries are mounted in individual racksand always provided with automaticcharging equipment.
Engine-Generator Sets are machinesintended to produce electricity andcomposed of three components: themachine and its housing (if any), fuelstorage tank and the exhaust facilities.
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EMERGENCY WIRING SYSTEMSUSING THE BATTERY
Small emergency appliance connecteddirect to a storage battery
Groups of emergency loadsconnected to central storage batterythrough automatic device
Emergency equipment loads are
entirely separate from normal loadsand are generally de-energized. Thecontactor is activated when it sensespower loss.
EMERGENCY WIRING SYSTEMSUSING THE GENERATOR
Emergency system handled by asingle transfer switch whichautomatically turns on when it sensespower loss at its downstream location.
Emergency system handled bymultiple switches
Emergency service totally separatedfrom normal through its own emergencyservice entrance, coming from differenttransformers or feeders.
Same as above, but both serviceentrances supply normal loads andeach act as standby for each other.
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are materials which allow the free
flow of electrons through them.
Wires are single insulatedconductors No. 8 AWG (American WireGauge or smaller; for the EnglishSystem, it is the B & S Gauge orBrowne and Sharpe Gauge. Thesmallest size of wire permitted is No.14.
Cables are single insulatedconductors No. 6 AWG or larger; orthey may be several conductors of
any size assembled into a single unit.
Bus Bars large conductors whichare not circular in cross section andusually found only to supply the mainswitch boards.
3. ELECTRICAL MATERIALS AND EQUIPMENT
3.1 CONDUCTORS
CONDUCTOR SIZES AWG/MCM STANDARD
All conductor sizes from No. 16 toNo. 0000 (also designated 4/0) areexpressed in AWG.Beyond AWG No. 4/0, a differentdesignation, MCM (or thousand circular mil)is used. In this designation, the smallestMCM size is 250 MCM or and thebiggest is 500 MCM.
A circular MIL is an artificial areameasurement, representing the square ofthe cable diameter (diam2) when thediameter is expressed in mils (thousands ofan inch). Thus a solid conductor inch indiameter is 500 mils in diameter, or250,000 circular mils in area, (500)2 or250 MCM; thus;CM/1000 = diam2 = (500)2/1000 =250,000/1000 = 250 MCMIn the metric system, conductor sizes aregiven simply as the diameter in millimeters(mm).
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CONDUCTOR AMPACITY
Conductor current carrying capacity orampacity is the maximum operatingtemperature that its insulation can standcontinuously. Heat is generated as aresult of the current flowing and theconductor resistance. When conductorsare placed in an enclosed conduit, theheat generated is not as easilydissipated as it would be if the conductorwere free in the air. Thus, the currentrating of a conductor in free air is muchhigher than that for the same were it ina conduit.
TYPES OF CABLES
Armored Cable (Type AC) a fabricatedassembly of insulated conductorsenclosed in flexible metal sheath.
Metal Clad Cable (Type MC) a factoryassembled cable of one or moreconductors each individually insulatedand enclosed in a metallic sheath ofinterlocking tape of a smooth orcorrugated tube.
Mineral Insulated Cable (Type MI) afactory assembled conductor/s insulated
with a highly compressed refractorymineral insulation enclosed in a liquid andgas tight continuous copper sheath.
Non-Metallic Sheathed Cable (Type NMor NMC) also known by the tradename ROMEX, is a factory assembly oftwo or more insulated conductors havinga moisture resistant, flame retardant,and non-metallic material outer sheath.
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Shielded Non-Metallic Sheathed Cable(Type SNM) a factory assembly of twoor more insulated conductors in anextruded core of moisture resistant and
flame retardant material covered withinan overlapping spiral metal tape.
Underground Feeder and Branch CircuitCable (Type UF) a moisture resistantcable used for underground connectionsincluding direct burial in the ground asfeeder or branch circuit.Service Entrance Cable (Type SE orUSE) a single or multi-conductorassembly provided with or without anoverall covering primarily used for servicewire.
Power and Control Tray Cable (Type TC) afactory assembled two or more insulatedconductors with or without associated bareor covered grounding under a metallic sheathand is used for installation in cable trays,raceways, or where supported by wire.
Flat Cable Assemblies (Type FC) anassembly of parallel conductors formedintegrally with an insulating material webdesigned specially for field installation insquare structural channels.
Flat Conductor Cable (Type FCC) consists of three or more flat copperconductors placed edge to edgeseparated and enclosed within ainsulating assembly. This type of cable
is used for appliance or individualbranch circuits installed inside floorsurfaces.
Medium Voltage Cable (MV) asingle or multi-conductor solid dielectricinsulated cable rated at 2,000 to35,000 volts. Trade name is Medium
Voltage Solid Dielectric.
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3.2 INSULATORS
INSULATORS are materials whichprevent the flow of electrons through
them.
General Wiring
Trade name Type
Letter
Maximum
Operating
Temperatur
e
ApplicationProvisions
Moisture-& heat-resistantrubber
RHW 75O C167O F Dry and wetLocations
Thermoplastic T 60O C140O F Dry locations
Moisture-resistant
thermoplastic
TW 60O C140O F Dry and wetLocations
Heat-resistant
thermoplastic
THHN 90O C194O F
Dry locations
Moisture-& heat-resistantthermoplastic
THW 75O C167O F Dry and wetLocations
Moisture-& heat-resistantthermoplastic
THWN 75O C167O F Dry and wetLocations
Moisture-& heat resistantcross-linkedthermosettingpolyethelene
XHHW 90O C194O F75O C167O C
Dry locationsWet
locations
Silicone-asbestos SA 90O C194O F Dry locations
Asbestos and VarnishedCambric
AVA 110O C230O F Dry locationsonly
TYPES OF INSULATORS
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CONDUITS are circular raceways usedto enclose wires and cables and are of
metal or plastic (PVC).
3.3 CONDUITS
To protect the enclosed conductorsfrom mechanical injury and chemicaldamage.
To protect people from shock hazardsby providing a grounded enclosure.
To provide a system ground path.
To protect the surroundings against firehazard as a result of overheating or shortcircuiting of the enclosed conductors.
To support the conductors.
TYPES OF STEEL CONDUITS
Heavy-wall steel conduits called RigidSteel Conduits or RSC with anapproximate thickness of 0.117 mm.
Intermediate Metal Conduit or IMC withthickness of 0.071 mm.
Thin-wall steel conduits named ElectricMetal Tubing or EMT.
RSCs and IMCs use the same fitting, called
condulets, and are threaded alike at thejoints. EMTs are not threaded but use setscrew and pressure fitting and are notrecommended for embedding in concretenor permitted in hazardous areas. IMCsyield a larger inside diameter (ID) foreasier wire pulling and is lighter than theRSC.Standard length of steel conduits is 3 M or10 ft.
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3.4 RACEWAYS are channels orwiring accessories so designed forholding wires, cables and bus bars thatare either made of metal, plastic, or any
insulating medium.
3.5 OUTLETS and RECEPTACLESAn outlet is a point in the wiring systemat which current is taken to supplyutilization equipment. It refers only tothe box. A receptacle is the wiringdevice in which the utilizationequipment (appliance) cord is pluggedinto.
Convenience Outlet or AttachmentCap - the complete set-up whichestablishes connection between theconductor of the flexible cord and theconductors connected permanently tothe receptacle.
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Lighting Outlet is an outlet intendedfor direct connection to a lamp holder,lighting fixture, or pendant cordterminating in a lamp holder.
Receptacle Outlet is an outlet whereone or more receptacles are installed.
3.6 SWITCHES are devices for making,breaking, or changing conditions in anelectrical circuit under the conditions ofload which they are rated.
TYPE OF SWITCH ACCORDINGTO VOLTAGESwitches are rated as 250V, 600V,or 5KVas required.
TYPE OF SWITCH ACCORDINGTO INTENSITY OF USE
1. Normal Duty (ND) intended fornormal use in light and power circuitsas in general-purpose switches.
2. Heavy Duty (HD) intended forfrequent interrupting.
3. Light Duty (LD)intended to connectthe loads occasionally, such as serviceswitches.
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TYPE OF SWITCH - ACCORDINGTO TYPE OF SERVICE
1. Service Switch intended todisconnect all the electric service inthe building except emergencyequipment. This may comprise one tosix properly rated switches that areassembled into a switchboard.
2. Power Switches
a) Generalpurpose switches areintended for use in generaldistribution and branch circuits.
b) Disconnecting or isolating switchesare intended for disconnecting orisolating circuits; used for circuitsrated at more than 600 volts.
a) Generalpurpose switches aresingle-pole or double-pole switchesfor the general purpose use ofconnecting or cutting-off circuits forthe control of lamps or other loadsfrom a single point.
b) Three-way switches are usedwhere it is desired to control lampsfrom two different points, as in astairwell.
c) Four-way switches are used inconjunction with two 3-wire switcheswhere it is desired to control lampsfrom three or more desired points.
3. Wiring Switches include all therelatively small switches that areemployed in interior wiringinstallations for the control ofbranch circuits, individual lamps orappliances.
d) Electrolier or multi-circuit switchesare used for the control of lights inmulti-lamp fixtures so that onelamp or set of lamps may be turnedon alone or in combination withother lamps.
e) Momentary contact switches areused where it is desired to connector cut-off a circuit for only a shortduration. The switch is providedwith a spring so that it will return toits original position as soon as the
handle or button is released.
f) Dimmer switches a rheostat[1] orsimilar device for regulating theintensity of an electric light withoutappreciably affecting spatialdistribution. Also called a dimmer.Wiring switches may either be theflush type, surface type or thependant type.
TYPE OF SWITCH - ACCORDING TO
OPERATION MECHANISMWiring switches may also be classified
according to the operating mechanismas:
1. Rotary switch2. Push-button switch3. Toggle or tumbler switch
TYPE OF SWITCH - ACCORDING TONUMBER OF POLES AND THROWS
1. Poles that part of the switch which isused for making or breaking of aconnection and which is electricallyinsulated from other contact making orbreaking parts.
2. Throws - a single throw switch is onewhich will make a closed circuit onlywhen the switch is thrown in oneposition. A double throw switch willmake a closed circuit when thrown ineither of two positions.
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SPECIAL SWITCHES
1. Time Controlled Switches Thisdevice comprises a precision low
speed miniature drive motor (timer)to which some type of electriccontact-making device is connected.
2. Remote Control (RC) Switches Acontactor[1], or more specifically, arelay[2], that latches after beingoperated wireless from a distance.
3.Air Switch a switch in which theinterruption of a circuit occurs in air.
4. Knife Switch a form of air switch inwhich a hinged copper bladeis placed between twocontact clips.
5. Float Switch a switch controlled bya conductor floating in a liquid.
6. Mercury Switch an especially quietswitch that opens and closes an electriccircuit by shifting a sealed glass tube ofmercury so as to uncover or cover thecontacts.
7. Key Switch a switch operated onlyby inserting a key or a card. Also calleda card switch.
8. Automatic Transfer Switch (ATS)This device, an essential part of anemergency or standby service, isbasically a double throw switch,generally 3-pole, so arranged that onfailure of normal power, emergencyservice is automatically supplied.
3.7 WALL PLATES OR FACEPLATES -These are coverings for switches and walloutlets usually made of metal or ofphenollic compound (Bakelite).
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3.8 OVER-CURRENT CIRCUITPROTECTIVE DEVICES are deviceswhose sole purpose is to protect
insulation, wiring, switches and otherapparatus from overheating or burning,due to overloads, to faults or to shortcircuits, by automatically cutting off thecircuit.
FUSE is a device consisting of analloy link of wire with a low meltingtemperature which is inserted in thecircuit, in such a way, that all current
which passes through the circuit, mustalso pass through this metal.
CIRCUIT BREAKERS is an over-current protective device designed tofunction as a switch, or it can bemanually tripped and thus act as acircuit switch. It breaks a circuit with anautomatic tripping device without injuryto itself.
GROUND FAULT CIRCUITINTERRUPTERS (GFCI or GFI) isan over current protective device thatwill provide ground fault protection aswell as function as an ordinary circuitbreaker.
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PANELBOARDS popularly known aspanel or electrical panel, it is simplythe box wherein the protective devises arehoused from which the circuits and bus
bars terminate.
SWITCHBOARDS are free standingassemblies of switches, fuses, and/orcircuit breakers whose function normallyis to provide switching and feederprotection to a number of circuitsconnected to a main source.
UNIT SUBSTATIONS (Transfer Load
Centers) an assembly of primary switch-fuse-breaker, step-down transformer,meters, controls, bus bars and secondaryswitchboard. It is used to supply powerfrom a primary voltage line to any largefacility.
4.1 WIRING METHODS
KNOB AND TUBE WIRING anobsolete wiring system consisting ofsingle insulated conductors secured toand supported on porcelain knobs andtubes. When wires run through walls,they are inserted into a nonmetallic fire-resistant tubing called a loom.
RIGID METAL CONDUIT WIRINGis the best and most expensive amongthe usual type of wiring. Its advantagesare:1. it is fireproof;2. moisture proof;3. it is mechanically strong so that nailscannot be driven through it and it is notreadily deformed by blows;4. it resists the normal action of cementwhen embedded in concrete or masonry.
4. WIRING SYSTEMS
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FLEXIBLE METAL CONDUITWIRING Its installation is mucheasier and quicker than that of rigidmetal conduits. Unlike the rigid conduits
which come in short lengths of 10 ft. (3M), flexible metal conduit wiring comesin length of 25 ft 250 ft (8 M 83 M)depending on the size of the conduit.
ARMORED CABLE WIRING (BXWIRING) consists of rubber orthermoplastic covered wire protectedfrom injury to a certain extent fromdampness by one or two layers of flexiblesteel armor.
SURFACE METAL RACEWAYWIRING the wires are supported on a
thin sheet steel casing. The raceway isinstalled exposed, being mounted on thewalls or ceiling. Metal raceways must becontinuous from outlet to outlet or
junction box, designed especially for usewith metal raceways.
FLAT CABLE ASSEMBLIES a fieldinstalled rigidly mounted squarestructural channel (15/8 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 forone to four circuits permanentlyinstalled in the track that will act aslight duty (branch circuit) plug-in
busways.
CABLE TRAY / OPEN RACEWAY is a continuous open support forapproved cables. When used as ageneral wiring system, the cablesmust be self-protected, jacketedtypes, type TC.
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FLOOR RACEWAYS The NECrecognizes three types of floorraceways:
1. Underfloor Ducts (UF) installed beneath
or flush with the floor. These underfloorducts usually requires a triple ductsystem for power, telephone andsignal cabling.
2. Cellular Metal Floor Raceway Foundusually in office landscaping, it is anintegrated structural/electrical systemin a cellular metal floor.
3. Precast Cellular Concrete made ofconcrete cells fed from header ducts,which are normally installed in concretefill above the hollow core structural slabor fed from the ceiling void below. Thecells can be used for air distribution andfor piping.
CEILING RACEWAY SYSTEMS under-the-ceiling raceways composed ofheader ducts and distribution ductsseparate for power and telephone cabling.They permit very rapid changes in layoutsat low cost and are therefore particularlydesirable in stores where frequent displaytransformations necessitate correspondingelectrical facility adjustments.
PRE-WIRED CEILING DISTRIBUTIONSYSTEMS are ceiling raceways that arepre-wired in the factory and plugged inwhere required.
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FEEDER
BRANCH CIRCUIT-CEILING/WALL
BRANCH CIRCUIT-FLOOR
3&4 WIRES CIRCUIT NO.MARK INDICATES 2 WIRES
CROSSING WIRES
CONNECTING WIRES
LIGHTING OUTLET CEILING
RECESSED CEILING OUTLETDASH INDICATES SHAPE OFFIXTURE
LIGHTING OUTLET WALL
FLUORESCENT LAMP
L LAMP HOLDER
PS LAMP HOLDER WITH PULL SWITCH
C
D
CLOCK OUTLET
DROP CORD OUTLET
F FAN OUTLET
R RADIO OUTLET
FLOOR OUTLET
CONVENIENCE OUTLET SPLIT-WIRED
DUPLEX CONVENIENCE OUTLET
WEATHER PROOF OUTLETWP
SOUTLET AND SWITCH
RRANGE OUTLET
SPECIAL PURPOSE OUTLET
refREFRIGERATOR OUTLET
PUSH BUTTON
BELL
BUZZER
CHIMECH
ANNUNCIATOR
LIGHTING PANEL
POWER PANEL
FUSE
WH WATT-HOUR METER
T TRANSFORMER
J JUNCTION BOX
GROUND
ELECTRICAL SYMBOLS
LIGHTING LAYOUT PLAN
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POWER LAYOUT PLAN
ELECTRICAL REGULATIONSBY PD 1096
1. General Locational Requirements in Towns,Subdivisions, Human Settlements, Industrial Estatesand the like.
Overhead transmission and/or distributionlines/systems including transformers, poles, towers andthe like shall be located and installed following thelatest standards of design, construction andmaintenance but so as not to cause visual pollution andin the interest of public safety, convenience, goodviewing and aesthetics, these may be located alongalleys or back streets.
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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 PoleLocation (APL) plan from the Municipal Engineer.
2.2 Poles and transformer supports shall be located not more than500mm inside from the road right-of-way or property line, andshall not obstruct the sidewalk, pedestrian path and/or the roaddrainage canal or structure, existing or proposed.
500 mm
Property line
Pole
2.3 Primary lines shall have a minimum vertical clearance of 10 mfrom the crown of the pavement when crossing the highwayand 7.5 m from the top of the shoulder or sidewalkwhen installedalong the side of the highway or street in a highly urbanized area.
10 m7.5 m
2.4 Secondary, neutral and service lines shall have a minimum verticalclearance of 7.5 m from the crown of the road pavement whencrossing the highway and from the top of the shoulder or sidewalkwhen installed along the side of the highway or street in highlyurbanized area.
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4. Open Supply Conductors Attached to Buildings
Where the permanent attachment of open supply conductors of any class tobuildings is necessary for an entrance such conductors shall meet the followingrequirements:
4.1 Conductors of more than 300 volts to ground shall not be carried along ornear the surface of the buildings unless they are guarded or madeinaccessible.
4.2 To promote safety to the general public and to employees not authorizedto approach conductors and other current-carrying parts of electric supplylines, such parts shall be arranged so as to provide adequate clearancefrom the ground or other space generally accessible, or shall be providedwith guards so as to isolate them effectively from accidental contact bysuch persons.
4.3 Undergrounded metal-sheathed service cables, service conduits, metalfixtures and similar noncurrent-carrying parts, if located in urban districtsand 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 contactby 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 thanthose required Table II.
4.5 Supports over buildings. Service-drop conductors passing over aroof shall be securely supported by substantial structures.Where practicable, such supports shall be independent of thebuilding.
Voltage of Supply
Conductors
Horizontal
Clearance in
Meters
Vertical Clearance
in Meters
300 to 8,700 volts 1.0 2.5
8,700 to 15,000
volts
2.5 2.5
15,000 to 50,000
volts
3.0 3.0
> 50,000 volts 3.0 + 10 mm per Kv
in excess
3.0 + 10 mm per Kv
in excess
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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 besideor over buildings. The vertical or horizontal clearance to anybuilding or its attachments (balconies, platforms, etc.) shall be aslisted below. The horizontal clearance governs above the rooflevel to the point where the diagonal equals the vertical clearancerequirement. This rule should not be interpreted as restricting theinstallation of a trolley contact conductor over the approximatecenter line of the track it serves.
5.2 Guarding of Supply Conductors/Supply of Conductors of 300 voltsor 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 cannotbe obtained.
2. Where such supply conductors are placed near enough towindows, verandas, fire escapes, or other ordinarilyaccessible places within the reach of persons.
5.3 Where the required clearances cannot be obtained, supplyconductors shall be of Grounded Metallic Shield, Jacketed PrimaryCables grouped or bundled and supported by grounded messengerwires.
V-
V
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Clearance of line
conductors from -
Communication LInes Supply LInes
In general On jointly used
poles
In general (0 to
8700 volts)
On jointly used
poles (0 to 8700
volts)
Exceeding 8700
volts, add for each
1000 volts of excess
Vertical and lateral
conductors of the
same circuit
75 mm 75 mm 75 mm 75 mm 6.25 mm
Vertical and lateral
conductors of other
circuits
75 mm 75 mm 150 mm 150 mm 10 mm
Span and guy wires
attached to same
pole: general
75 mm 150 mm 150 mm 150 mm 10 mm
Span and guy wires
attached to same
pole: when parallel
to line
75 mm 150 mm 300 mm 300 mm 10 mm
Lightning protection
wires parallel to line:
surfaces of crossarms
75 mm 75 mm 75 mm 75 mm 5 mm
Lightning protection
wires parallel to line:
surfaces of poles
75 mm 125 mm 75 mm 125 mm 5 mm
6. Clearance of Service Drops
6.1 Service drop conductors shall not be readily accessible and when not inexcess of 600 volts, shall conform to the following:
a. Clearances over roof. Conductors shall have a clearance of not lessthan 2.5m from the highest point of roofs over which they pass withthe following exceptions:
2.5 m
Highest point
Service Drop Conductor< 600 volts
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Exception No. 1. Where the voltage between conductors does not exceed 300volts and the roof has a slope of not less than 100mm in 300mm, theclearance may not be less than 1m.
1 m
Highest point
Service Drop Conductor300 volts
Slope 1:3
Exception No. 2. Service drop conductors of 300 volts or less which do not passover other than a maximum of 1.2m of the overhang portion of the roof for thepurpose of terminating at a through-the-roof service raceway or approvedsupport may be maintained at a minimum of 500mm from any portion of theroof over which they pass.
1.2 m
Highest point
Service Drop Conductor 300 volts
500mm
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6.2 Clearance from the Ground. Conductors shall have a clearance of not lessthan 3m from the ground or from any platform or projection from which theymight be reached.
conductor
platform 3 m
6.3 Clearance from Building Openings. Conductors shall have a horizontalclearance of not less than 1m from windows, doors, porches, fire escapes, orsimilar locations and shall be run at least 500mm above the top level of awindow or opening.
window
500mm
1 m
6.4 Service Drop of communication lines, when crossing a street, shall have aclearance of not less than 5.5 m from the crown of the street or sidewalkover which it passes.
5.50 m 5.50 m
Service drop of communication line
Service Drop of communication lines shall have a minimum clearance of 3mabove ground at its point of attachment to the building or pedestal.
3mprotector
3m
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6.5 No parts of swimming and wading pools shall be placed under existing servicedrop conductors or any other over-head wiring; nor shall such wiring beinstalled 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 Structuresc. Observation stands, towers or platforms
Swimming pool
Servicedropconductor
3 m
7. Wiring Methods
Service entrance conductors extending along the exterior or enteringbuildings or other structures shall be installed in rigid steel conduit orasbestos cement conduit or concrete encased plastic conduit from point ofservice drop to meter socket and from meter socket to the disconnectingequipment. However, where the service entrance conductors are protectedby approved fuses or breakers at their outer ends (immediately after theservice drop or lateral) they may be installed in any of the recognized wiringmethods.
7.1 Abandoned Lines and/or portions of lines no longer required to provideshall be removed.
7.2 Power or communication poles, lines, service drops and other lineequipment shall be free from any attachment for antennas, signs,streamers and the like.
7.3 Metallic sheaths or jackets of overhead power or communication cablesshall be grounded at a point as close as possible to ground levelwhenever such cables change from overhead to undergroundinstallations.
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8. Transformers
8.1 Oil-insulated Transformers Installed Outdoors. Combustible material,combustible buildings and parts of buildings, fire escapes, door andwindow openings shall be safeguarded from fires originating in oil-
insulated transformers installed on, attached to, or adjacent to a buildingor combustible material. Space separations, fire-resistant barriers andenclosures which confine the oil of a ruptured transformer tank arerecognized safeguards. One or more of these safeguards shall be appliedaccording to the degree of hazard involved in cases where the transformerinstallation 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 incases where the exposure and the quantity of oil involved are such thatremoval of oil is important.
Trench allaround
Exterior Oil-insulatedTransformer
8.2 Dry-Type Transformers Installed Indoors. Transformers rated 112-1/2 KVAor less shall have separation of at least 300mm from combustible materialunless separated there from by a fire-resistant heat-insulating barrier orunless of a rating not exceeding 600 volts and completely enclosed except forventilating openings.
Dry-type transformer112-1/2 Kva or less
300mm
Combustible Wall
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8.3 Askarel-Insulated Transformers Installed Indoors. Askarel-insulatedtransformers rated in excess of 25 KVA shall be furnished with a pressurerelief vent. Where installed in a poorly ventilated place they shall befurnished with a means for absorbing any gases generated by arcing insidethe case, or the pressure relief vent shall be connected to a chimney or fluewhich will carry such gases outside the building. Askarel-insulatedtransformers rated more than 35,000 volts shall be installed in a vault.
Transformers of more than 112-1/2 KVA rating shall be installed in a transformerroom of fire-resistant construction unless they are constructed with Class B (80Crise) or Class H (150C rise) insulation, and are separated from combustiblematerial not less than 1.85m horizontally and 3.7m vertically or are separatedthere from by a fire-resistant heat-insulating barrier.
Transformers rated more than 35,000 volts shall be installed in a vault.
Dry-type transformer112-1/2 Kva or less
1.85 m
CombustibleWall
Combustible ceiling
3.70 m
vault
Transformer morethan 35,000 volts
8.4 Oil-Insulated Transformers Installed Indoors. Oil-insulated transformers shall
be installed in a vault constructed as specified in this Section except as follows:
1. NOT OVER 112-1/2KVATOTAL CAPACITY. The provisions for transformervaults specified in Section 9.3 of this Rule apply except that the vault maybe constructed of reinforced concrete not less than 100mm thick.
2. NOT OVER 600 VOLTS. A vault is not required provided suitablearrangements are made where necessary to prevent a transformer oil fireigniting other materials, and the total transformer capacity in one locationdoes not exceed 10 KVA in a section of the building classified ascombustible, or 75 KVA where the surrounding structures is classified asfire-resistant construction.
> 100mm thick reinforcedconcrete vault
oil insulated transformer< 112-1/2 KVa
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8.5 Guarding. Transformers shall be guarded as follows:
1. MECHANICAL PROTECTION. Appropriate provisions shall be madeto minimize the possibility of damage to transformers from externalcauses where the transformers are located exposed to physicaldamage.
2. CASE OR ENCLOSURE. Dry-type transformers shall be provided witha non-combustible moisture resistant case or enclosure which will
provide reasonable protection against accidental insertion of foreignobjects.
3. EXPOSED LIVE PARTS. The transformer installation shall conformwith the provisions for guarding of live parts in PEC Rule 1056.
4. VOLTAGE WARNING. The operating voltage of exposed live parts oftransformer installations shall be indicated by signs or visiblemarkings on the equipment or structures.
3. FURNACE TRANSFORMERS. Electric furnace transformers of a total ratingnot exceeding 75 KVA may be installed without a vault in a building or roomof fire-resistant construction provided suitable arrangements are made toprevent a transformer oil fire spreading to other combustible material.
4. DETACHED BUILDING. Transformers may be installed in a building whichdoes not conform with the provisions specified in this Code for transformervault, provided neither the building nor its contents present fire hazard toany other building or property, and provided the building is used only insupplying electric service and the interior is accessible only to qualifiedpersons.
9. Provisions for Transformer Vaults
9.1 New Building. New buildings requiring an expected load demand of200KVA or above shall be provided with a transformer vault, except thattransformers may be mounted on poles or structures within the property ifenough space is available, provided that all clearances required can beobtained and no troublesome contamination on insulators, bushings, etc.can cause hazards and malfunctioning of the equipment.
150 mm for R.C200 mm for Brick300 mm for Load bearing CHB
200 Kva or moreWall:
20 mm thick plaster2-1/2 hours fire rating
Floor:100mm thick2-1/2 hours fire rating
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9.2 Location. Transformer and transformer vaults shall be readily accessible toqualified personnel for inspection and maintenance. Vaults shall be locatedwhere they can be ventilated to the outside air without using flues or ductswherever such an arrangement is practicable.
9.3 Walls, Roof and Floor. The walls and roofs of vaults shall consist of reinforcedconcrete not less than 150mm thick, masonry or brick not less than 200mmthick, or 300mm load bearing hollow concrete blocks. The inside wall and roofsurface of vaults constructed of hollow concrete blocks shall have a coating ofcement or gypsum plaster not less than 20mm thick. The vault shall have aconcrete floor not less than 100mm thick. Building walls and floor which meetthese requirements may serve for the floor, roof and one or more walls of thevaults. Other forms of fire-resistive construction are also acceptable providedthey have adequate structural strength for the conditions and a minimum fireresistance of two and one half hours according to the approved Fire TestStandard. The quality of the material used in the construction of the vault shallbe 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-fittingdoor of a type approved for openings in such locations by the authorityenforcing this Code.
2. SILLS. A door sill or curb of sufficient height to confine within thevault, the oil from the largest transformer shall be provided and in nocase shall the height be less than 100mm.
3. LOCKS. Entrance doors shall be equipped with locks, and doors shallbe kept locked, access being allowed only to qualified persons. Locks
and latches shall be so arranged that the door may be readily andquickly opened from the inside.
10.Ventilation. Ventilation shall be adequate to prevent a transformer temperaturein excess of the prescribed values.
1. LOCATION. Ventilation openings shall be located as far away aspossible from doors, windows, fire escapes and combustible material.
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2. ARRANGEMENT. Vaults ventilated by natural circulation of air may haveroughly half of the total area of openings required or ventilation in one or moreopenings near the floor and the remainder in one or more openings in the roofor 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 orflues the combined net area of all ventilating openings after deducting the areaoccupied by screens, grating, or louvers, shall be not less than 0.006 sqmm perKVA of transformer capacity in service, except that the net area shall be notless 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 toavoid unsafe conditions.
5. DAMPERS. Where automatic dampers are used in the ventilation openings of
vaults containing oil-insulated transformers, the actuating device should bemade to function at a temperature resulting from fire and not a temperaturewhich might prevail as a result of an overheated transformer or bank oftransformers. Automatic dampers should be designed and constructed tominimize the possibility of accidental closing.
6. DUCTS. Ventilating ducts shall be constructed of fire resistant material.
7. DRAINAGE. Where practicable, vaults containing more than 100KVAtransformer capacity shall be provided with a drain or other means which willcarry off any accumulation of oil or water in the vaults unless local conditionsmake this impracticable.
8. WATER PIPES AND ACCESSORIES. Any pipe or duct system foreign to theelectrical installation should not enter or pass through a transformer vault.Where the presence of such foreign system cannot be avoided, appurtenancesthereto which require maintenance at regular intervals shall not be locatedinside 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-cooledtransformers are not deemed to be foreign to the electrical installation.
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11.Capacitors.
1. Application. This section applies to installation of capacitors on electriccircuits 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 withadditional requirements in PEC Section 400-415.
2. Location. An installation of capacitors in which any single unit containsmore than three gallons of combustible liquid shall be in a vault conformingto part C of PEC Section 319.
3. Mechanical Protection. Capacitors shall be protected from physical damageby location or by suitable fences, barriers or other enclosures.
4. Cases and Supports. Capacitors shall be protected from physical damage bylocation or by suitable fences, barriers or other enclosures.
5. Transformers Used with Capacitors. Transformers which are components ofcapacitor installations and are used for the purpose of connecting thecapacitor to a power circuit shall be installed in accordance with PEC Section319. The KVA rating shall not be less than 135 per cent of the capacitorrating in Kva.
12.Emergency Systems
1. The provisions of this Section shall apply to the installation, operation andmaintenance of circuits, systems and equipment intended to supplyillumination and power in the event of failure of the normal supply or in theevent of accident to elements of a system supplying power and illuminationessential for safety to life and proper where such systems or circuits arerequired by the Fire Code, or by any government agency having jurisdiction.
Emergency systems are generally installed in places of assembly whereartificial illumination is required, such as buildings subject to occupancy bylarge numbers of persons, hotels, theaters, sports arenas, hospitals and similarinstitutions. Emergency systems provide power for such functions as
refrigeration, operation of mechanical breathing apparatus, ventilationessential to maintain life, illumination and power for hospital room, fire alarmsystems, fire pumps, industrial processes where current interruption wouldproduce 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.
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4. Tests and Maintenance
a. The authority having jurisdiction shall conduct or witness a test on thecomplete system upon completion of installation, and periodically afterwards.
b. Systems shall be tested periodically in accordance with a schedule acceptableto the authority having jurisdiction to assure that they are maintained in properoperating condition.
c. Where the battery systems or unit equipment are involved, includingbatteries 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 emergencyoperation of all equipment connected to the system.
6. Current supply shall be such that in the event of failure of the normal supply toor within the building or group of buildings concerned, emergency lighting oremergency power, will be immediately available. The supply system foremergency purposes may be composed one or more of the types of systemscovered in Section 12.7 to Section 12.10 of this Rule. Unit equipment inaccordance with Section 12.21 shall satisfy the applicable requirements of thisSection.
Consideration must be given to the type of service to be rendered; whether forshort duration, as for exit lights of a theater, or for long duration, as forsupplying emergency power and lighting during long periods of current failurefrom trouble either inside or outside the buildings, as in the case of a hospital.
Assignment of degree of reliability of the recognized emergency supply systemdepends upon the careful evaluation of the variables of each particularinstallation.
7. A storage battery of suitable rating and capacity shall supply, by means of aservice installed according to Section 200 of the PEC and maintained at notmore than 90 per cent of system voltage, the total load of the circuits supplyingemergency lighting and emergency power for a period of at least hour.
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8. A generator set driven by some form of prime mover, with sufficient capacityand proper rating to supply circuits carrying emergency lighting or lighting andpower, 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 emergencygenerator 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 ofsimultaneous interruption of power supply arising from an occurrence withinthe building or group of buildings served.
10.Connections on the line side of the main service shall be sufficiently separatedfrom said main service to prevent simultaneous interruption of supply throughan occurrence within the building or group of buildings served.
11. The requirements of Section 12.5 and Section 12.6 also apply to installationswhere the entire electrical load on a service or sub-service is arranged to besupplied from a second source. Current supply from a standby power plantshall satisfy the requirements of availability in Section 12.6.
12.Audible and visual signal devices shall be provided, where practicable, for thefollowing 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 besupplied by emergency lighting circuits.
14. Emergency illumination shall be provided for all required exit lights and allother lights specified as necessary for sufficient illumination.Emergency lighting systems should be so designed and installed that thefailure of any individual lighting element, such as the burning out of a lightbulb, shall not leave any area in total darkness.
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15.Branch circuits intended to supply emergency lighting shall be so installed as toprovide 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 lightingsystem with provisions for automatically transferring to the emergencylights by means of devices approved for the purpose upon the event offailure of the general lighting system supply.
b. Two or more separate and complete systems with independent powersupply, each system providing sufficient current for emergency lightingpurposes. Unless both systems are used for regular lighting purposesand are both lighted, means shall be provided for automaticallyenergizing either system upon failure of the other. Either or bothsystems may be part of the general lighting system of the protectedoccupancy if circuits supplying lights for emergency illumination areinstalled in accordance with other Section of this Rule.
16. For branch circuits which supply equipment classed as emergency, there shallbe an emergency supply source to which the load will be transferredautomatically 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 wiringexcept:
a. In transfer switches, orb. In exit or emergency lighting fixtures supplied from two (2) sources.
18. The switches installed in emergency lighting circuits shall be so arranged that onlyauthorized persons have control of emergency lighting, except:
a. Where two or more single throw switches are connected in parallel tocontrol a single circuit, at least one of those switches shall be accessibleonly to authorized persons.
b. Additional switches which act only to put emergency lights into operationbut not to disconnect them may be permitted.
Switches connected in series and three- and four-way switches shall not beallowed.
19. All manual switches for controlling emergency circuits shall be located at the mostaccessible place to authorized persons responsible for their actuation. In places ofassembly, such as theaters, a switch for controlling emergency lighting systemsshall 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 motionpicture projection be placed in the projection booth or on the stage. However,where multiple switches are provided, one such switch may be installed in suchlocations and so arranged that it can energize but not disconnect for the circuit.
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20. Lights on the exterior of the building which are not required for illuminationwhen there is sufficient daylight may be controlled by an automatic lightactuated device approved for the purpose.
21. In hospital corridors, switching arrangements to transfer corridor lighting inpatient areas of hospitals from overhead fixtures to fixtures designed to providenight lighting maybe permitted, provided that the switching system is sodesigned that switches can only select between two sets of fixtures but cannotextinguish both sets at the same time.
22.The branch circuits over current devices in emergency circuits shall beaccessible to authorized persons only.
23. Where permitted by the authority having jurisdiction, in lieu of other methodsspecified elsewhere in this Section, individual unit equipment for emergencyillumination shall consist of:
a. Batteryb. Battery charging means, when a storage battery is usedc. One or more lamps, andd. 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 theunit for a period of at least hour. Storage batteries, whether of the acid or alkalitype, shall be designed and constructed to meet the requirements of emergencyservice. Lead-acid type storage batteries shall have transparent jars.
Unit equipment shall be permanently fixed in place and shall have all wiring to eachunit installed in accordance with the requirements of any of the wiring methodsdiscussed in Chapter II of the PEC. They shall not be connected by flexible cord. Thesupply circuit between the unit equipment and the service, the feeders or the branchcircuit wiring shall be installed as required by Section 12.17. Emergency illuminationfixtures which obtain power from a unit equipment which are not part of the unitequipment shall be wired to the unit equipment as required by Rule 5257 of the PECand 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 theprovisions 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 therequirements of this Rule. Transformer installations already existing shall comply withthe 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 penalprovisions in Section 213 of PD 1096.
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