Chapter - Six. Electrical Construction and Documentation

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Reginald Carter
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1 Chapter - Six Electrical Construction and Documentation 1 Electrical Contracting Works An engineering project in which electrical installation works include may be residential, public, commercial buildings; entertainment complexes; industries, etc. 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) 2 1

2 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 3 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 4 2

3 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 5 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. 6 3

4 Typical construction work flow 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. Installation engineer prepares tender document offers and considerations to the specified design. 3. 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. 7 Typical construction work flow (contd) 4. The client/owner prepares bid/tender for construction based on the design drawings and specification of the construction 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 5. Contractor/Construction Companies bid to win the construction work 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 8 4

5 Typical construction work flow 6 Awarded contractor/construction company takes up the construction 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 9 Typical construction work flow 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. 10 5

6 Typical construction work flow 7. The construction is tested and commissioned and handed over for 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 licensed entity. Participate in commissioning document preparation and signature. 11 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 12 6

7 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 13 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 14 7

8 Contract document: Electrical Construction Specification 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 15 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. 16 8

9 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. 17 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. 18 9

10 BoQ of material, labor and cost estimating in an electrical installation work Any electrical installation construction work requires quantifying material cost and labor cost. Estimation of these costs helps a client/owner to award an eligible contractor as well as secure budget and release a right portion at the right time. Determination of these costs helps a contractor to decide to venture or not on the contract. The consultant uses the cost information to monitor the work as well as deploy the right amount of money at the right time to the contractor. To determine these costs determining the types and extent/quantity of works involved is essential. Furthermore, probable variation of work, change of currency in time, labor and material cost variations etc should be accounted as contingency. 19 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

11 List of works in an installation include II. Feeder cable running from transformer house to MDB 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. III. MDB installation 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 21 List of works in an installation include IV. Feeder cable running from MDB to (isolator switches, if any, of) SDBs 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. SDB Installations 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 11

12 23 List of works in an installation include VI. Branch circuit wire/s or cable running 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) VII. Installation of receptacles and fixtures This involves installation of light switches, lighting fixtures, socket outlets, etc at designated points on walls and ceilings GO VIII. Installation of backup power system 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 24 12

13 25 List of works in an installation include XI. Installation of power factor correction system 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 >> at a designated position with associated switch gear XI. Installation 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.Installation Installation of lightening protection system >> for the building and campus premises XIII.Testing of the interconnections considering essential points of test and appropriate testing procedure 26 13

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16 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 31 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 32 16

17 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 33 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 34 17

18 Sample bill of quantities of electrical installation materials Sample BOQ! 35 18

Section 70 Airport Transformer Vault and Vault Equipment (FAA L-109)

Section 70 Airport Transformer Vault and Vault Equipment (FAA L-109) Black text from standard FAA spec Strikeout text deletions from FAA standard spec Blue text additions to FAA standard spec Red text notes to the Engineer/won t appear in spec I. DESCRIPTION 1. This item