EEE3 Lec13 - Electrical System Design

8/8/2019 EEE3 Lec13 - Electrical System Design

1/84

Elec

tricalSy

stemD

esign

Lec

ture9

EEE

3SWX

March

2,

2002


2/84

Elec

tricalSy

stemD

esign

Amatter

ofprovidin

ganarran

gementof

conducto

rsandequ

ipmenttosafelyand

effectivelytransferelectricene

rgyfroma

sourceofpowertolamps,motorsand

otherfun

ctionaldev

iceswhich

operateon

electricity

.


3/84

Respo

nsibilitie

sofan

Electric

Des

igner

Ensureco

nformitytoa

pplicableco

desand

standards

(PEC).

Studyand

establishth

eelectricalneedsofthe

building.

Determine

thecharacteristicsofth

eenergy

supplytotheoverallsystem.

Scaledeta

ilsoftheov

erallelectric

alsystemto

meetthelimitationsof

budgetedfu

nds.


4/84

BasicS

tepsinElectricalDesig

n

Selectb

asicwiring

concepts

and

configurationswhichwills

upplyelectric

powero

ftherequiredcharac

teristicsat

eachpo

intofutilization.


5/84

BasicS


n

Implementtheelectricalconce

ptswith

actualco

nductors,apparatusand

hardware

,selecting

types,sizes,models

,

characteristics,app

earance,ratingsand

otherspe

cificsofth

erequired

equipment.


6/84

BasicS


n

Accountfortheinstallationoftheoverall

electricalsystem,asdeterminedinthe

firsttwo

steps,withinthephy

sical

dimensionsandstructuredm

akeupofa

building

,showing,

asclearly

as

possible

,thelocationsanddetailsof

equipmentmountings,racew

ayruns,

connectionstoma

inpowers

upplylines

,

andotherelementsthatrequ

irespecial

attention.


7/84

Characterist

icsofa

Good

ElectricalDesig

n

Flexibility

Thela

youtandtyp

eofequipm

entshould

readilyaccommod

atechangesinthe

locatio

nsofmotorsandotherutilization

device

s.

Feede

rs,

distributionpanelboardsand

circuitsshouldbe

suitedtoaw

iderangeo

f

utilizationpatterns

,allowingfu

lland

efficientuseofpowercapacity

foractivities

inthe

buildingsva

riousareas.


8/84

Characterist

icsofa

Good

ElectricalDesig

n

Accessib

ility

Thedesignofthesystemmustprovideease

ofaccesstoequipm

entformain

tenanceand

repaira

ndforanyp

ossibleexte

nsions,

modificationsoralte

rationstoth

esystem.


9/84

Characterist

icsofa

Good

ElectricalDesig

n

Reliability

Continu

ityofelectricalsupplyandoverall

reliabilityofthewiringsystemcanbemoreor

lessan

importantconsideration

dependingon

thenatureoftheac

tivitieswithinthebuilding.


10/84

PreliminaryConsidera

tionsin

System

Design

I.Determin

ethecharacteristicsofthe

building

Smallo

rlarge?

Singles

toryormulti-level?

Typeof

building(industrialplant,office

building

,school,hospital,etc.)


11/84

D

etermin

eBuilding

Charac

teristics

Thesech

aracteristicsgiveinsighttothe

typesofelectricalutilization,theneedfor

flexibility,

theacces

sibilityofthesystem

andthed

utycycles

ofvarious

load

devices.


12/84

D

etermin

eBuilding

Charac

teristics

Planningforthedesignofan

electrical

system

shouldbeginwiththe

determinationand

studyofth

esizeand

natureo

fthetotall

oadtobe

served.Th

is

involves

:

Appro

ximationoflightingloads(VApersq

m.)

Analysisofthenumberandsizesofmotor

s.

Determinationoftheamounts

ofother

utilizationloads.


13/84

D

etermin

eBuilding

Charac

teristics

Afullund

erstanding

ofallload

stheir

sizesand

pointsofapplication

is

essentialtothesele

ctionofthebesttype

ofdistributionsystem.


14/84


tionsin

System

Design

II.

Standa

rdizeEquipment

Maxim

umstandardizationine

quipment

typea

ndratingsshouldalwaysbeadesig

n

object

ive.

Selectionofstandardvoltagelevelsresults

insign

ificanteconomysincestandard-

ratedtransformers

,switchgear,motors,

motorsandotherequipmentc

ostlessthan

specifiedequipme

ntfornon-standard

voltag

es.


15/84

StandardizeEquipment

Lackofs

tandardiza

tioncomplicates

maintena

ncesince

replaceme

ntpartsare

noteasy

toobtain,alargeinventoryof

partsand

equipmen

tmustbemaintained

andthee

fficiencyo

fthemaintenance

personne

lisreduce

d.


16/84

StandardizeEquipment

Theuseofspecial,

non-standard

equipmentandvoltagesmayseriously

impairex

pansionoradulterationofthe

electricalsystemat

alaterdat

e.


17/84


tionsin

System

Design

III.Provide

theSystemPowerS

upply

Thepowermaybesuppliedby

eitherthe

distributionsystemofanelectricutility

compan

yoraprivategeneratingplant.

Selectt

hebest-suitedtypeofdistributionto

carryth

eelectricalloads.


18/84


19/84

ThePh

ilippine

Electric

alCode

Strictcom

pliancew

iththeprovisionsofthe

codewille

nsuresafetyinelec

trical

installatio

nandconstruction,b

utnot

necessarilyefficient,convenie

ntor

adequate

forgoodserviceorfuture

expansio

nofelectricaluse.


20/84

Classification

ofCodeRules

1.

Wiring

DesignRules

2.

Wiring

InstallationRules

3.

EquipmentManu

facturingR

ules


21/84

Classification

ofCodeRules

Thecode

rulesmay

alsobeclassifiedas

:

Mandatory

-

shall

Advisor

y

-

should


22/84

Electrica

lPermits

Owners,

lessors,op

eratorsor

occupants

shouldobtainthefo

rmattheg

overnmen

t

agencyc

oncerned.

Itshallbe

accomplished,signedandsub

mittedbya

dulyregisteredProfessionalE

lectrical

Engineer

.


23/84

Electrica

lPermits

Exception

Installationwithligh

tingandorreceptacle

outletsnotexceedin

g20or400

0VA,

230

volts,th

eapplicationmaybepreparedbya

dulyreg

isteredAssociateElectricalEnginee

r,

anAssistantElectricalEngineeroraMaster

Electrician.


24/84

ElectricalI

nspect

ion

Anapplicationforinspection

shallbe

filedwiththegovernmentagency

concern

edbefore

aprelimina

ryand/or

finalins

pectionisdone.

Noelec

tricalinstallation,alte

ration

and/ora

dditionshallbeconn

ectedor

reconne

ctedtoanypowersu

pplyorany

otherso

urceofele

ctricalene

rgywithou

t

acertificateofinspectionobt

ainedfrom

thegovernmentagencyconc

erned.


25/84

Branch

Circuits

Definition

Abranc

hcircuitisa

nysegment

ofawiring

system

extendingb

eyondthefinalautomatic

overcur

rentprotectivedeviceth

atisapproved

foruse

asbranchcircuitprotection.


26/84

TypesofBranchCircuits

Individua

lbranchcircuit

Branch

circuitthatd

eliverspowertoonlyon

e

load.

Thisma

yhaveany

currentratin

g.


27/84


28/84

BranchCircuitRa

ting

Abranch

circuitisratedaccordingtothe

settingorratingoftheovercur

rentdevice

usedtop

rotectthecircuit.


29/84

PermissibleLoadsin

Branch

Circuits

15&20

-AmpsBra

nchCircuits

Mays

ervegenera

lpurposelig

htingand/or

applia

nces.

Thera

tingifanyo

ne-cordand

plug-

conne

ctedapplian

cemustnotexceed80%

of

thebranchcircuitrating.

Theto

talratingof

utilizationequipment

fasten

edinplaceshallnotexc

eed50%of

the

branchcircuitamp

ereratingw

herelighting

and/orutilizatione

quipmentnotfastenedinto

place

arealsosup

plied.


30/84

PermissibleLoadsin

Branch

Circuits

30-AmpB

ranchCirc

uits

Mayser

vefixedligh

tingunitswithheavy-duty

lamp-ho

ldersinothe

rthandwellingunits.

Mayser

veutilization

equipment

inany

occupan

cy.

Theratingofanyon

e-cordandplug-

connectedutilization

equipment

shallnot

exceed80%oftheb

ranchcircuitampere

rating.


31/84

PermissibleLoadsin

Branch

Circuits

40&50-AmpBranc

hCircuits

Mayservecooking

appliancesthatare

fastenedinplacein

anyoccupa

ncy.

Maysupplyfixedlig

htingunitsw

ithheavy-

dutylam

p-holders,infraredheatingunitsan

d

otherutilizationequ

ipmentinotherthan

dwellingunits.


32/84

PermissibleLoadsin

Branch

Circuits

Largerth

an50-AmpBranchC

ircuits

Mustsu

pplyonlyno

n-lightingoutletloads.


33/84

Require

dOutlets

1.

Require

dRecepta

cleOutlets

in

Dwellings

a)General-purposeconvenience

outlets

Rule:Receptacleoutletsshallbe

installedso

thatnopointalongthefloorlin

einanywall

space

ismorethan1800mm,

measured

horizo

ntally,

fromanoutletinthatspace,

includ

inganywalls

pace600mmormore

in

width.


34/84

Require

dRece

ptacleO

utletsin

Dwe

llings

b)Small-a

ppliancereceptacleo

utlets

Rule:outle

tsinthekitchen,pantry,

breakfa

st

room,d

iningroom

,orsimilarareasina

dwellingunitshallb

eserved

byaSA

branch

circuit.

The

reshallbe

noother

outletsinsuchcircuits.


35/84

Require

dRece

ptacleO

utletsin

Dwe

llings

c)CounterTops

Rule:Inkitchensand

diningareasof

dwellingunitsare

ceptacleoutletshallbe

installedateachc

ounterspa

cewider

than30

0mm.


36/84

Require

dRece

ptacleO

utletsin

Dwe

llings

d)Bathrooms

Rule:Indw

ellingunitsatleastonewall

receptacleoutletsh

allbeinsta

lledinthe

bathroom

adjacenttothebasinlocation.


37/84

Require

dRece

ptacleO

utletsin

Dwe

llings

e)Outdoo

rs

Rule:Atleastoneoutletaccessibleatgrad

e

level.


38/84


39/84

Require

dRece

ptacleO

utletsin

Dwe

llings

g)Baseme

ntsandGarages

Rule:Atleastonerec

eptacleou

tletin

additiontoanyprov

idedforlaundry

equipmentshallbe

installedin

each

basemen

tandinea

chgarage.


40/84

Require

dRece

ptacleO

utletsin

Dwe

llings

h)Hallway

s

Rule:Forh

allwaysof

3000mmormorein

lengtha

tleastone

receptacleoutletis

required.


41/84


42/84

Require

dOutlets

3)Requiredlightingo

utletsindw

ellingunit

s

Rule:Atleastonewa

llswitch-co

ntrolled

lightingo

utletshallbeinstalledinevery

habitable

room;inb

athrooms,

hallways,

stairways

,attached

garagesa

nddetached

garageswithelectricpower,andat

outdoore

ntrancesorexits.


43/84


44/84

RequiredLightingOu

tletsin

DwellingUnits

Rule:Wherelightingoutletsare

installedin

interiorstairways,thereshallb

eawall

switchat

eachfloor

leveltoco

ntrolthe

lightingo

utletwherethedifference

between

floorlevelsissixstep

sormore.


45/84

Require

dOutlets

4)Require

dlightingoutletsing

uestrooms

Rule:Atleastonewa

llswitch-co

ntrolled

lighting

outletorw

allswitch-controlled

recepta

cleshallbeinstalledinguest

roomsinhotels,m

otelsorsimilar

occupancies.


46/84

Maxim

umLoa

dsAllowedon

Branch

Circuits

Theratin

gofabran

chcircuits

erving

continuousloadssh

allnotbelessthanthe

non-continuousloadplus125%ofthe

continuousload.

Continuo

usloadloadwhere

the

maximum

currentis

expected

tocontinue

foratleastthree(3)hours.


47/84

Calculationso

fBranchCircuit

Lo

ads

1)Lighting

andrecep

tacleloadsforgener

al

illumina

tion

Largerof:

Volt-A

mperesper

sqmareaoflisted

occup

ancies[Table3.3.1.2

(b)],or

Actualload,

ifknown.


48/84

Lighting

andReceptacleLoads

forGeneralIllumination

Receptacleoutletsof20Aorlessinone-

familyor

multi-familydwellingsoringuest

roomsof

hotelsand

motelsareconsidered

aspartofthegenerallightingload.

BranchC

ircuitRating:15or20A


49/84

Table3.3.1.2

(b)Ge

neral

Lighting

Loads

byOccupancies

28

OfficeBuildings

16

Restaurants

24

Schools

24

Stores

2

Warehouses

(storage)

16

Hotels/Motels

16

Hospitals

4

Garages-Commercial

24

DwellingUnits

UnitLoad

persqm(VA)

TypeofOccupancy


50/84

Calculationso

fBranchCircuit

Lo

ads

2)Heavy-d

utylamp-h

oldersinfixedlighting

units

Largerof:

600VA

perunit,or

Actualloadifknown

Branchc

ircuitrating

:30,

40or50A


51/84

Calculationso

fBranchCircuit

Lo

ads

3)GeneralR

eceptacles

Largerof:

180VA

perrecepta

cle,or

Actualload,

ifknow

n

BranchC

ircuitRating:15or20A


52/84

Calculationso

fBranchCircuit

Lo

ads

4)Showwindowillum

ination

Largerof:

180VA

peroutlet,o

r

600VA

perlinearm

eter,or

Actualloadifknown

Branchc

ircuitrating

:depends

ontypeof

lamphold

er


53/84


54/84

Calculationso

fBranchCircuit

Lo

ads

6)SmallAppliancefo

rDwelling

Unit

Largerof:

1500VA

180VA

peroutlet,o

r

Actualload,

ifknow

n

Branchc

ircuitrating

:20A


55/84

Calculationso

fBranchCircuit

Lo

ads

7)Laundry

Loadsfor

DwellingU

nits

Largerof:

1500VA

180VA

peroutlet,o

r

Actualload,

ifknow

n

Branchc

ircuitrating

:20A


56/84

Calculationso

fBranchCircuit

Lo

ads

8)ElectricRangesand

CookingEq

uipmentin

Dwellings

8to12KWr

ange:8KW

Largerth

an12KWrange:8KWf

orfirst12

KWp

lus

5%foreach

additionalKW

exceedin

g12KW

Smallerthan8KW

range:FLC

Onerangetopandn

otmorethan2ovens:

Addthetotaloftheir

separateratings,

then

proceed

aswithrang

es.

Branchc

ircuitratings

:40or50A


57/84

Calculationso

fBranchCircuit

Lo

ads

9)Electricrangesinc

ommercialbuildings

Ampereratingofap

pliance

Branchc

ircuitrating

:40or50

A


58/84

Calculationso

fBranchCircuit

Lo

ads

10)Motorloads

Fullload

currentofmotorx1

25%

Branchc

ircuitrating

:anyratin

g


59/84

Minim

umNum

berofBranch

Circuits

capacity

circuit

Br

anch

r

eqd.

BC

per

VA

in

load

comp

uted

Total

B.C.

of

No.

=


60/84

Exa

mple

Determin

etheminimumnumb

erofbranch

circuitsrequiredfor

anofficeb

uildingwith

thefollow

inglightingandreceptacleload

s:

Floorareaof30mby60m

Fourhu

ndred150-W

incandesc

entlamps

15mlongShowwindow

Speciall

ightingload

of100fluorescent

lighting

fixtures,eac

hunitdraws2.5

A

Twohundredduplexreceptacle

s

Use20A

mpB.C.


61/84

Solution

a)Gener

alillumination

Largerof:

(30m

)(60m)(28V

A/sqm)=50

,400VA,or

(400

units)(150V

A/unit)=60,0

00VA

BC)

per

lamps

2

4

(max

(m

inimum)

Circuits

Branch

17

BC

#

(230V)

(0.8)(20A)V

A

60,000

BC

#

=


62/84

Solution

b)Showwindow

(15m)(600A/m)=900

0VA

(minimum)

BC

3

BC

#

(230V)

(

0.8

)(20A)V

A

9000

BC

#

=


63/84

Solution

c)SpecialL

ightingLoad

(100units)(2.5

A/unit)(230V)=57

,500VA

(m

inimum)

BC

16

BC

#

(230V)

(0.8

)(20A

)VA

57500

BC

#

=


64/84

Solution

d)Generalr

eceptacle

(200units)(180VA/un

it)=36,00

0VA

(minim

um)

BC

10

BC

#

(23

0V)

(0

.8)(20A)VA

36000

BC

#

==


65/84

FeedersforLig

htingan

dPowe

r

GeneralRule

Afeede

rmusthave

sufficientcapacitytoca

rry

thetota

lloadofthe

branchcircuits.


66/84

Feeder

Capacity

Whenafeedersuppliesacon

tinuousloa

d

oracombinationof

continuousornon-

continuousloads,theratingofthefeeder

conducto

rsandove

rcurrentdevicemust

notbelessthanthe

non-continuousload

plus125%oftheco

ntinuousload.


67/84

FeederDem

andFa

ctors

GeneralLighting

Table3.3.2.2

Recepta

cleLoads:non-dwellingunits

Table3.3.2.4

ApplianceLoad:Dwellingunits(4or

moreap

pliancesnotincludingelectric

ranges,

clothesdry

ers,space

heating

equipme

ntorair-conditioning

equipme

nt.DF=

75%

Clothes

dryers:Dw

ellingunitstable

3.3.2.9


68/84

FeederDem

andFa

ctors

ElectricR

angesandothercoo

king

appliances:dwellingunitsTable3.3.2.

10

Kitchene

quipment:

non-dwellingunits

Table3.3

.2.1

1


69/84

MotorBra

nchCircuit

Elemen

tsofMotorBranchCircuits

Disconnectingmeans

Overc

urrent(short-circuit)protection

Condu

ctors

Controller

Overlo

adprotectio

n

Motor

Secon

darycontrollerandresistorsfor

wound

rotormotor


70/84

MotorFullL

oadCu

rrent

ThefullloadcurrentgivenbythePEC

shouldbeusedind

etermining

thebranch

circuitof

amotor.

Thefullloadnamep

latecurren

t,ifknown

,

isusedo

nlyindeterminingthe

ratingor

settingoftheoverlo

adprotectivedevice.


71/84

Motor

Disconnecting

Means

Theratin

gofthedisconnectingmeansfo

r

motorcircuitsrated

upto600Vshallbe

at

least115

%ofthefu

llloadcurrentrating

of

themotor.

MustberatedinHP

formotorsupto500

HP.


72/84

Branch

CircuitConductorsfora

Single

Motor

BasicRu

le

Conduc

torsshallha

veanampa

cityofnotle

ss

than12

5%ofthem

otorfull-load

rating.


73/84

MotorBranchCircuitShort

CircuitP

rotectio

n

Rule

Themo

torbranchc

ircuitshortc

ircuit

protectivedevicesh

allbecapableofcarryin

g

thestar

tingcurrent

ofthemotor

whichshall

notexceedthevalu

ecalculated

accordingto

Table6

.6.1

2.6


74/84

MotorBranchCircuitO

verload

Protection

For1HPupto1500

HP

Aseparateovercurre

ntdeviceresponsive

to

motorcurr

ent,ratedorselected

totripatn

o

morethan

thefollowingpercentageofthe

motorfullrating:

Motorsw

ithmarkedservicefacto

rofnotless

than1.15

125%

Motorsw

ithmarkedtemperature

risenotove

r

40C1

25%

Allother

motors115%


75/84

ElectricalSys

temDesignfor

ResidentialOccupa

ncies

ClassificationofDw

ellingTypesAccording

toPEC

Single-FamilyDwelling

Two-Fa

milyDwellin

g

Multi-familyDwelling


76/84

Scop

eofPre

misesWiring

System

Branchc

ircuitsina

dwellingunit

Feeders

toindividualdwelling

unitsina

multifamilydwelling

service


77/84

Calculatio

nMethods

Standard

calculationmethod

Optionalc

alculation

method


78/84

Bran

chCircuitDesignfor

Dwe

llings

Generallightingandreceptaclebranch

circuits

24VA/s

qmoffloorarea.

15Aor

20Abranch

circuitcapacity.

Atleast

2.0mm2for15Acircuitor3.5mm2for

20Acir

cuitcopperconductors.


79/84

Bran

chCircuitDesignfor

Dwe

llings

SmallAp

plianceBranchCircu

its

1500VA

20Abranchcircuit

Atleast

3.5mm2co

pperwire


80/84

Bran

chCircuitDesignfor

Dwe

llings

LaundryBranchCir

cuit

1500VA

20Abranchcircuit

Atleast

3.5mm2co

pperwire


81/84


82/84

Bran

chCircuitDesignfor

Dwe

llings

Motorbranchcircuit

Applyrulesformoto

rs


83/84

Feede

rorSer

viceDe

signfor

DwellingUnits

StandardCalculat

ionMethod

a.

Generallightingandreceptacleloads:24

VA/m2

b.

Smalla

ppliancelo

ad:

1500

VA/ckt

c.

Laund

rycircuit:

1500

VA/ckt

TotalG

en.

Lighting

Load____

VA

ApplyD

emandFa

ctorstoco

mpute

feederload

1st3000VAat100%


84/84

de

rorSer

viceDe

signfor

DwellingUnits

erloads

yspecificdem

andfactorsfor:

othe

sdryers

ectricranges

Documents

EEE3 Lec13 - Electrical System Design