school of electrical and computer engineering addis ababa ... · school of electrical and computer...

22-Sep-14

1

1

Addis Ababa Institute of Technology

School of Electrical and Computer Engineering

Addis Ababa University

Chapter - Six

Electrical Construction and Documentation

2




An engineering project in which electrical installation works include

may be residential, public , commercial buildings; entertainment

complexes; industries, etc.

Electrical Contracting Works

In such projects, generally the following sub-works are involved:

i. Architectural work

ii. Structural and building works

iii. Sanitation work

iv. Electrical installation work

v. Data, telephone, access control system, fire alarm & security system,

vi. Lift/escalator systems

vii. MATV [Master Antenna Television System] and PAS [ Public announcer

system ] system

viii.HVAC system

ix. Building Management Systems (BMS)

22-Sep-14

2

3




Contracting parties

In an engineering project of the above type at least three

main parties are involved, viz.,

� The client

� The consultant, and

� The contractor

4




The client

� The client is generally the owner of a project for which much no.

of the above sub works may be involved.

� The client may be an individual, a business firm/company, an NGO

or a public/ govt entity

22-Sep-14

3

5




The consultant

� The consultant is a firm of qualified and experienced team of

various professionals (architects, civil, electrical, computer etc

engineers )

� The team may be under one license or a consortium of licensed

professionals

The consultant’s main functions are:

� to design one or more of the above sub works for the client

� to supervise & inspect the correct implementation of the

design on behalf of the client until commissioned.

� Serves as the coordinators of the whole or sub-work

Since it is usually difficult to hire and maintain professionals of all

spectrum, the consultant may out source some of the works to sub

contractor/s

6




The contractor

� The contractor is a firm that may be owned by a lay or professional

business man/woman but consisting of :

� sufficient number of qualified , skilled engineers and technicians

� sufficient construction facilities and equipment

� sufficient financial capital

� The main function of the contractor is to implement each of the

above construction/installation designs in the project according to

the design & supervision provided by the consultant

� For the service it rendered, the contractor is paid by the client.

� The contractor, like the consultant, may out source some of its

duties to sub contractor/s.

22-Sep-14

4

7




Typical construction work flow1. A client/owner wants electrical installation construction done 1. A client/owner wants electrical installation construction done 1. A client/owner wants electrical installation construction done 1. A client/owner wants electrical installation construction done

�The client will have prepared a tender document using own

expert or external consultant

� In either case, an installation engineer (an expert of the client or

an employee of the consultant) participates in the preparation of

the tender document especially in specifying the design work.

�The tender is floated for design companies to compete

2. Consultant/Design companies bid to win the design work.2. Consultant/Design companies bid to win the design work.2. Consultant/Design companies bid to win the design work.2. Consultant/Design companies bid to win the design work.

� Installation engineer prepares tender document “offers and

considerations” to the specified design.

3. Winning consultant company prepares the design3. Winning consultant company prepares the design3. Winning consultant company prepares the design3. Winning consultant company prepares the design

�A contract is signed b/n the client and the design consultant

� Installation engineer designs the electrical installation for the

construction as the employee of the consultant or a consultant.

8




Typical construction work flow… (contd)4444.... TheTheTheThe client/ownerclient/ownerclient/ownerclient/owner preparespreparespreparesprepares bid/tenderbid/tenderbid/tenderbid/tender forforforfor constructionconstructionconstructionconstruction basedbasedbasedbased onononon thethethethe

designdesigndesigndesign drawingsdrawingsdrawingsdrawings andandandand specificationspecificationspecificationspecification ofofofof thethethethe constructionconstructionconstructionconstruction

� Installation engineer participates in preparation of tender

document especially in specifying the construction or installation

work

� The installation engineer does this as an employee of the client

or consultant

5555.... Contractor/ConstructionContractor/ConstructionContractor/ConstructionContractor/Construction CompaniesCompaniesCompaniesCompanies bidbidbidbid totototo winwinwinwin thethethethe constructionconstructionconstructionconstruction

workworkworkwork

� Installation engineer participates in estimation of material and

labour cost of the construction and prepares tender document

“offer and condition” in response to the design document.

� The installation engineer does this as an employee of a

contractor or a self competent contractor

22-Sep-14

5

9




Typical construction work flow

6 Awarded contractor/construction company takes up the 6 Awarded contractor/construction company takes up the 6 Awarded contractor/construction company takes up the 6 Awarded contractor/construction company takes up the

constructionconstructionconstructionconstruction

� A contract is signed b/n the client/owner and the awarded

contractor

� Installation engineer prepares shop/layout drawing, specifies

materials, gets approval of the consultant, participates or

supervises wiring work to be done according to design and

applicable regulations

� The installation engineer does the supervision and wiring works in

coordination with other disciplinary works such as structural,

sanitary, HVAC, data-telecom, MATV, etc

10





� The installation engineer produces as-built drawings for

documentation purpose that account alterations and

modifications of original drawings

� The installation engineer does this as a contractor, employee of

the contractor, or as counterpart for the owner.

22-Sep-14

6

11





7. The construction is tested and commissioned and handed over for 7. The construction is tested and commissioned and handed over for 7. The construction is tested and commissioned and handed over for 7. The construction is tested and commissioned and handed over for

operation.operation.operation.operation.

� Electrical Engineer with necessary licence participates in testing

and commissioning as representative engineer for the owner,

representative for the contractor, licensed inspection engineer,

etc.

8. Inspection and commissioning done and document prepared by 8. Inspection and commissioning done and document prepared by 8. Inspection and commissioning done and document prepared by 8. Inspection and commissioning done and document prepared by

licensed entity.licensed entity.licensed entity.licensed entity.

� Participate in commissioning document preparation and

signature.

12




Expectations from Electrical engineers in installation work

�Electrical engineers participate in the construction work as

contractors, subcontractors, employees of contractors, employees of

the owner of the construction, or as consultants.

� In all cases electrical engineers are faced with preparing essential

documents in addition to the design and construction engineering

work they are usually ready for.

� In addition to the engineering knowledge they have, electrical

engineers need legal and writing skills which are usually obtained

through experience and use of proper references.

�As an example of a contract document we will discuss here about a

construction work based on the design and additional specifications

22-Sep-14

7

13




Contract

� A contract is an agreement in the form of written text as well as

drawings among partakers of a project

� The content of the contract includes

� The qualitative, technical and material specifications of the project

� Methodologies of carrying out the project etc

� The duties and responsibilities of the client, the consultant and

contractor

� The contract serves :

� To correctly and smoothly implement each of the project sub

works

� To resolve any probable disputes

14




Contract

� The contract document is prepared by own/external experts

entrusted by the client

� Contracts are signed between agreeing parties

The following are usually considered parts of the contract:

� The bid/tender document

� Design drawings

� Offered documents in response to bid

A project contract is usually managed/coordinated by the architect

22-Sep-14

8

15




Contract document: Electrical Construction Specification

General Provision (Typical)General Provision (Typical)General Provision (Typical)General Provision (Typical)

1. Portions of the sections of the documents in the other part of the

work (civil, mechanical, etc.) under “General Requirements” apply to

this too.

2. Refer to index to be certain that set of documents and specifications

is complete. Report omissions or discrepancies to the architect.

3. Scope of the work

16




The scope of the work consists of

� furnishing and installing of complete electrical system exterior and

interior –including miscellaneous systems.

� The electrical contractor shall provide all supervision, labor,

materials, equipment, machinery, and any and all other items

necessary to complete the systems.

� The electrical contractor shall note that all items of equipments are

specified in the singular;

� however, the contractor shall provide and install the number of

items of equipment as indicated on the drawings and as required

for complete systems.

22-Sep-14

9

17




� It is the intention of the specification and drawings to call for

finished work, tested, and ready for operation.

� Any apparatus, appliance, material, or work not shown on the

drawings but mentioned in specification, or vise versa or any

incidental accessories necessary to make the work complete and

perfect in all aspects and ready for operation even if not

particularly specified shall be furnished, delivered and installed by

the contractor without additional expense to the owner.

18




� Minor details not shown or specified but necessary for proper

operation shall be included in the contractor’s estimate the same as if

herein specified or shown.

� With submission of bid the electrical contractor shall give written

notice to the architect of any materials or apparatus believed

inadequate or unsuitable in violation of laws, ordinances, rules and any

necessary items or work omitted.

� In the absence of such written notice it is mutually agreed that the

constructer has included the cost of all required items in this proposal,

and that he will be responsible for the approved satisfactory

functioning of the entire system with out extra compensation.

22-Sep-14

10

19




BoQ of material, labor and cost estimating in an electrical installation work

� Any electrical installation construction work requires quantifyingmaterial cost and labor cost.

� Estimation of these costs helps a client/owner to award an eligiblecontractor as well as secure budget and release a right portion at theright time.

� Determination of these costs helps a contractor to decide to venture ornot on the contract.

� The consultant uses the cost information to monitor the work as wellas deploy the right amount of money at the right time to thecontractor.

� To determine these costs determining the types and extent/quantity ofworks involved is essential.

� Furthermore, probable variation of work, change of currency in time,labor and material cost variations etc should be accounted ascontingency.

20




List of works in an installation include

I. Manual layout of flush (within slab or wall) and/or surface mounted

conduits/raceways and junction boxes for the whole installation

based on the shop drawing version of the installation schematic

drawing.

� This is required for power feeder cables from transformer to MDB,

from MDB to SDBs, from each SDB to SDBs and/or branch circuits,

from branch circuits to outlets and appliances, etc,

� Concrete ducting (for SDB inter connection of branch circuits) and

manhole construction (underground cable running through PVC

conduit) should also be made in consultation with civil

contractors.

� To avoid collisions with water supply and sewerage lines, HVAC

lines etc, consultation should also be made with respective

engineers/technicians ON THE SITE.

22-Sep-14

11

21




List of works in an installation includeIIIIIIII.... FeederFeederFeederFeeder cablecablecablecable runningrunningrunningrunning fromfromfromfrom transformertransformertransformertransformer househousehousehouse totototo MDBMDBMDBMDB

� This involves laying under ground (with PVC or concrete duct) or

overhead mounting on poles of feeder cable from transformer house

after kWh & kVARh meters and isolator switch to MDB in the building

main control room.

� Cable splicing (twisting and/or soldering, insulating, etc) to lengthen

� Cable termination/connection at the transformer house is part of this

work.

IIIIIIIIIIII.... MDBMDBMDBMDB installationinstallationinstallationinstallation

� Mounting the MDB enclosure at the designated site on a wall

(recessed) or in a closet (surface)

� Assembling of entrance isolator switch, bus bars, protective earth,

protective CBs & fuses, etc and terminal interconnections in the MDB

22




List of works in an installation include

IV.IV.IV.IV. FeederFeederFeederFeeder cablecablecablecable runningrunningrunningrunning fromfromfromfrom MDBMDBMDBMDB totototo (isolator(isolator(isolator(isolator switches,switches,switches,switches, ifififif any,any,any,any, of)of)of)of) SDBsSDBsSDBsSDBs

�This involves drawing of feeder cables through flush or surface

mounted PVC conduits, concrete ducts and/or metalic raceways.

�Cable splicing (twisting and/or soldering, insulating, etc) to lengthen

�Cable termination/connection at each SDB is part of the work

V.V.V.V. SDBSDBSDBSDB InstallationsInstallationsInstallationsInstallations

�Mounting each SDB enclosure at the designated site on a wall

(recessed) or in a closet (surface)

�Assembling of isolator switch (if any), CBs, fuses, bus bars, protective

earth, etc and terminal & branch circuit interconnections in each SDB at

the designated site/s on a wall (recessed) or in a closet (surface)

22-Sep-14

12

23




24




List of works in an installation includeVIVIVIVI.... BranchBranchBranchBranch circuitcircuitcircuitcircuit wire/swire/swire/swire/s orororor cablecablecablecable runningrunningrunningrunning

�Branch circuit wires/cables are drawn through conduits (flush) in ducts

or race ways (surface) from each SDB to junction boxes for termination,

tapping etc.

�The cables/conductors are drawn from junction boxes to appliance

outlet (light point, light switch, socket outlet, or appliance)

VIIVIIVIIVII.... InstallationInstallationInstallationInstallation ofofofof receptaclesreceptaclesreceptaclesreceptacles andandandand fixturesfixturesfixturesfixtures

�This involves installation of light switches, lighting fixtures, socket

outlets, etc at designated points on walls and ceilings

VIIIVIIIVIIIVIII.... InstallationInstallationInstallationInstallation ofofofof backupbackupbackupbackup powerpowerpowerpower systemsystemsystemsystem

�This involves installation of diesel generator set, PV system, and/or wind

turbine system/s at a designated site in the premises

�Includes laying of cables from the backup system to the exchange

switch center, interconnection with associated switch gear (ATS or

manual exchange switch) on the MDB

GO

22-Sep-14

13

25




26




List of works in an installation includeXIXIXIXI.... InstallationInstallationInstallationInstallation ofofofof powerpowerpowerpower factorfactorfactorfactor correctioncorrectioncorrectioncorrection systemsystemsystemsystem

� This involves installation of capacitor bank and/or reactor at a

designated position with associated automatic or manual switch gear

XI. Installation of harmonic filters XI. Installation of harmonic filters XI. Installation of harmonic filters XI. Installation of harmonic filters

� at a designated position with associated switch gear

XI.XI.XI.XI. Installation of groundingInstallation of groundingInstallation of groundingInstallation of grounding

� This involves installation of operational grounding and protective

grounding

� Protective grounding may involve neutralization, protective earthing

with/without earth leakage detection and reacting device

� Verification of design parameters on site measurements should be done

XII.XII.XII.XII.Installation of Installation of Installation of Installation of lightening protection system lightening protection system lightening protection system lightening protection system

� for the building and campus premises

XIII.XIII.XIII.XIII.Testing Testing Testing Testing

� of the interconnections considering essential points of test and

appropriate testing procedure

>>

>>

>>

>>

22-Sep-14

14

27




Back

28




Back

22-Sep-14

15

29




Back

30




Back

22-Sep-14

16

31




BOQ of works and materials� In ordinary projects, a contractor supplies only labor while the client

purchases required materials either on a grant or on a bid competitive

basis from suppliers.

�Payment to the contractor is made after completion of a distinct phase

of the project

� In a more autonomous project, both materials and labor are supplied

by the contractor itself.

� In a turn key project, all design, materials and labor are supplied by the

contractor itself.

� In any case, the shop drawing/layout diagram (usually on 2D

AutoCAD floor plan) generated from the schematic/wiring diagram

(and refined on site after award) helps a lot in estimating the BoQ of

materials.

�3D shop drawing/layout diagrams (e.g. using Autocad or CadPIPE)

facilitates even more the determination of BoQ faster and accurate

32




We recall the AutoCAD drawing shows

1) the actual route, number, length, and diameter of conduits in each floor

slab and in wall (and/or in raceways on walls/ceilings) of the building

determined on the basis of the number and size of cables each carries

2) the position, number and sizes of the junction boxes, concrete ducts,

outlets and appliance positions in each floor slab and walls (and/or on

walls/ceilings) of the building

3) The number, type, size and colour of cables/conductors to be run in each

conduit/raceway and connected in each junction box

4) The position of SDBs, MDB and service entrance

5) The position of, if any, transformer, backup power system, switching

system etc in a house/control room

6) The position of earth and lightening protection

22-Sep-14

17

33




Accordingly, from a scaled drawing of the shop drawing, we can

read/count all essential parameters such as length, diameter, number etc of

the installation materials used in the installation work

Conduit/raceway works

�Conduit/raceway layout work includes laying, tying, lengthening,

cutting, bending, etc in slabs, walls, or ducts (flush) or mounting on

walls, ceilings, etc (surface)

� The associated work (labor) as well as the quantity of material is

conveniently rated by linear meter.

� Thus the linear meter serves for quantifying the required

conduit/race way as well as for costing of conduit/raceway layout

work

� The material and labor costs may thus be rated with Birr/linear

meter/mm sq of conduit or raceway

34




Junction box and duct works

� Junction box layout work includes mounting the boxes in slab and in

wall (flush) or on wall and on ceilings (surface), tying it,

conduit/raceway fitting, etc

� The associated work (labor) as well as the quantity of material is

conveniently rated by the count in number, size and type of junction

boxes on each of the floors

� The material and labor costs may thus be rated Birr/junction box/box

size

22-Sep-14

18

35




Sample bill of quantities of electrical installation materials

Sample BOQ!

school of electrical and computer engineering addis ababa ... · school of electrical and computer...

Documents