This adopted report covers practical experience in Electrical Engineering for Building Services industry. There are two stages in this report;
- Consulting for Electrical Engineering.
- Contracting for Electrical Engineering.
They are the rudiment of construction work in building services.
Electricity gave rise to work and practice of electrical installation. Electrical installation projects comprise of various types of electrical materials, apparatus, and equipment interconnected with cables and conductors in fixed position ready for use.
Regulation, codes and procedures exist to guarantee the safety and regular supply of electrical energy.
Compliance with this regulations and procedures during installation ensures that the premises so connected, as well as the users of electricity, are protected from electrical accidents, shocks, fire outbreak and other problems, which may result from bad electrical installation works.
The following statutory regulations are compulsory in the work and practice of electrical installations.
- The Electricity act CAP 106, Law of the Federal Republic of Nigeria (LFN) 199- comprising :
- Electrical Installation Regulation 1994
- Electricity Supply Regulations
- The Health and Safety at work act HASAW 1974
- The Institute of Electrical Engineers Regulations (Known as IEE regulations)
This regulation, specializations, code of practice has been drawn up to provide adequate guidance, laws and requirements for the actual erection of electrical equipment and apparatus in any premises. The regulation also ensures that electrical materials and equipment comply with the relevant international standard and specifications.
In the building industry, a team of professionals worked together to achieve a meaningful goal.
The following are the professionals’ participants in the building industry:
- Project manager.
- Civil Engineer.
- Structural Engineer.
- Electrical Engineer
- Mechanical Engineer
The above participants generate and build the knowledge and ideas of construction and make sure that the process and method of achievement are put into operation.
The fact that participants come from different fields, there should be the need for a common language to communicate and make the ideas of construction to be actualized, and thus, the CONSTRUCTION DRAWING comes into play.
Since effective communication is what harmonizes the various participants in the field, DRAWING is the tool used for effective communication.
1.1 TYPES OF DRAWINGS
- ARCHITECTURAL DRAWING: This is the first drawing that brings out the idea of construction; it shows the shape, size, elevations, roof plan, site plan etc. of the building. This is circulated to other participants so that the concept of construction can be adhered to.
- STRUCTURAL DRAWING: This drawing gives us the exact calculation of the structures of the building, like how many irons are needed, or how much gravel and cement should be mixed.
- ELECTRICAL DRAWING: Still from the architectural drawing, the electrical engineer designs how the electricity distribution, power networking, load distribution etc. works.
- MECHANICAL DRAWING: This brings back the water supply system, Air-conditioning, waste management channel to the septic tank.
- WORKSHOP DRAWING: This is a working drawing for site workers. The already designed M&E drawing is simplified to a more explanatory one for site work.
- AS-BUILT DRAWING: This is a more comprehensive drawing. It’s the conclusive drawing in construction after commissioning of a project/construction. It is given to clients for maintenance and repairs.
ESSENTIALS OF DRAWINGS
- All the drawings mentioned above, are generated from the concept (idea) of construction and are worked upon by the entire participant in the field.
- The various drawing will be submitted to the PROJECT MANAGER and approved before the actual site work begins as authentic for the project.
- Having done this, it brings effective communication among the construction participant; it also serves as a reference point before, during and after construction.
- It provides the engineering details for workers in the industry, such that without the engineer on site, work can keep going.
- It is also a useful tool to raise Bills of Engineering Measurement and Evaluation (BEME).
- Comprehensive list of material (material-take-off) could be measured from drawings before site work begins.
- So many times, it has resolved the conflict between participants on the field; because it serves as a document for reference.
2.0 DESIGN OF ELECTRICAL SYSTEM IN BUILDINGS (CONSULTING).
The point below elaborates on how the concept and knowledge of Design on projects in planning department is carried out:
(b) ELECTRICAL SYSTEM IN BUILDINGS
2.1 DESIGN: A structured approach to developing a solution to a problem.
An integral part of the larger and more complex is the procurement process through which a potential owner defines facility needs and engages consultants who would then design the facility.
A good design must meet the owner and occupants’ satisfaction.
PHASES OF DESIGN PROCESS
- Pre-design activities
- Conceptual design
- Design development
- Final design
- The design process converts the brief into Drawings, Specifications and BEME.
- The design process starts with some pre-design activities where the client/owner establishes the need for, the feasibility of and the scope for the facility
- Output: A clearly defined scope of works for the design team to act upon (project brief or owner’s project requirement).
- Outline a general solution.
- Outline the basic areas designed.
- Final design/construction design/tender drawing.
A statement of the expected outcomes of the design process that is, the solution that meets the expectations of the owner. e.g. outstanding comfort, a high degree of safety, environmentally friendly, adequate luminance level.
Benchmarks for measuring/evaluating achievement of the intent e.g. thermal conduction will meet e.g. lighting levels will be by CIBS/IESNA.
METHODS AND TOOLS
Method and tool of achieving design item e.g. hand calculation, computer software, and simulator. These tools above facilitate the design development and final design.
FACTORS THAT INFLUENCE THE DESIGN PROCESS
Codes, standard and other design guides:
- Government documents that stipulate minimum acceptable building practices. They have the power of law and are mandatory and enforced e.g. Nigeria building code.
- The requirements of codes may not by itself meet the requirements of a client.
- Documents that prescribe a set of the minimum requirement for a different aspect of a building, these are usually developed by consensus in recognized professional organizations (e.g. IEE, IEEE, BSI, ASHRAE) under stipulated procedures with public review and input.
- Documents by the professional group but with less public involvement
- The client may impose a maximum construction budget on the project
- Life cycle cost of the project.
ENVIRONMENT AND ENERGY
- Environmental and energy efficiency consideration are now becoming a part of the design process, this has been because of worldwide concern for Energy and Environmental energy challenges e.g. global warming and use of renewable energy.
- Buildings are now required to minimize negative impacts of the site, local, national and global environment.
2.2 ELECTRICAL SYSTEMS IN BUILDINGS
The electrical system in a building includes but not limited to the following;
- LIGHTING SYSTEM
- POWER SYSTEM
- TELECOMMUNICATION SYSTEM
- SECURITY SYSTEM
The lighting system provides suitable quantity and quality of light in each enclosure that will meet the requirement of the visual task to be performed in that enclosure/premises. It also provides switches and other controls for the lights.
The quantity of light reaching the surface of an enclosure is usually the main consideration in designing a lighting system.
This quantity of light is specified by illuminance measure in Lux, and as this level varies across the working plain, an average figure is used.
CIBSE lighting guides give values of illuminance that are suitable for various areas.
The lumens method is used to determine the number of lamps that should be installed for a given area
Number of lamps is given by the formula;
N = Number of lamps required
E = Illuminance level required
A = Area at working plane height (m2)
F = Average luminous flux from each lamp (lm)
UF = Utilization factor, an allowance for light distribution of the luminaire and the room surface.
MF = Maintenance factor, an allowance for reduced light output because of deterioration and dirt.
This system brings sufficient power into the building from the Service Provider and distributes the power to all equipment using electricity.
Provide an adequate number of telephone/intercom, data, and television outlets at strategic and important places according to the client’s desire.
Provide adequate numbers of camera outlets at strategic and important places especially, public areas, garage, the perimeter of the premises, entrance and exit areas.
2.3 LIGHTING DESIGN IN THE BUILDING
- The goal of lighting is to create a pleasant and efficient interior
- Provide adequate light for the visual tasks
- Fixtures to enhance the interior and be unobtrusive.
- Provide quality lighting by uniform illuminance level and by minimizing the negative effects of direct and reflected glare.
- Minimize energy usage while achieving the visibility, quality and aesthetic objectives.
GENERALLY, A GOOD LIGHTING DESIGN SHOULD
- Look good!
- Provide the proper amount of light in every room.
- Be built and constructed within budget, code, and other constraints.
- Be environmentally responsible.
- Respond to Architecture and Interior Design.
- Produce a good colour.
- Achieve the desired moods of each space.
- Be able to control the lights.
- Several international bodies have set up Criteria for lighting these include
- CIBSE – Chartered Institute of Building Services Engineers
- IES – Illuminating Engineering Society
2.4 POWER DESIGN IN THE BUILDING
- SAFETY of Life and Property is paramount
GENERALLY, A GOOD POWER DESIGN SHOULD
- Be safe from all hazards, abuse and misuse
- All equipment must have adequate working spaces and be free from all obstructions to access spaces.
- Be reliable and provide continuous service.
- Make provisions for expansion and growth and at the same time not being over-designed.
- Be able to accommodate all probable locations and arrangements of electrical loads
Criteria for power design include:-
- BS 7671:2008 – Requirements for Electrical Installations (IEE Wiring Regulations 17th Edition)s 1-9)
- Regulations for Electrical Installations, Sections 3 and 4 of the Electrical Act Cap 106, Laws of the Federation of Nigeria.
- National Building Code of the Federal Republic of Nigeria (1st Edition of 2006).
- Nigerian Electricity Regulatory Commission (NERC) and Power Holding Corporation of Nigerian (PHCN) Regulations
- Other relevant Local Authority Building Regulations where these are not inferior to generally acceptable Engineering Practices
METHODS FOR ELECTRICAL SYSTEM DESIGN
- Design the Lighting.
- Locate all electrical equipment, power outlets and power using apparatus on the plans.
- Locate all ELVS equipment i.e. telephone and data outlets, fire alarm, CCTV, TV points etc.
- Circuit all lighting, power, and other equipment to their appropriate control/power panels
- Prepare load Schedules
- Determine from other consultants the locations and power requirement of their equipment.
- Estimate overall loads
- Prepare Distribution Schematics
- Compute cable sizes for all electrical equipment,
- Decide (with PHCN) the service voltage, entrance point, metering etc.
- Determine the locations and sizes of all equipment to ensure that adequate spaces are made available for them by the Architect.
- Ensure coordination with the work of other Consultants throughout the entire procedure.
TOOLS USED FOR ELECTRICAL SYSTEM DESIGN
INTRODUCTION: Contract Administration is the whole process of contract procurement to the delivery. It is aimed at ensuring that projects are properly and effectively managed to the satisfaction of all parties.
DEFINITION: Contract is an agreement between two or more parties to offer a service in return for money or other forms of consideration.
CONSTRUCTION TEAM: As explained in chapter one, the team is responsible for the implementation of the design concept. It comprises of the design team members, main contractor and sub-contractors. The main difference is that the contracts agreements must be involved.
PHASES OF CONTRACT ADMINISTRATION: Contract administration activities span majorly between two phases viz;
- Pre-contract phase.
- Post contract phase.
4.1 PRE-CONTRACT PHASE: This aspect has been discussed and it involves all activities relating to the placing of contract up to the Award of contract. That includes;
Brief stage, Designs, Designs approval, Costing and budget preparation/BEME, Preparation of tender documents, Tender invitation and negotiation, Selection of the contractor, Award of contract. The duration of this phase depends on the complexity of the project.
4.2 POST-CONTRACT PHASE: This phase is termed as the project implementation phase. This phase commenced with the mobilization of the contractor to the site for the actual construction works. It involves organising, supervising and other management processes of actualising the project’s delivery. The competence of the contractor and the availability of the fund goes a long way in determining the project’s delivery period. The following management’s processes take place during the post-contract phase of the project.
SITE SUPERVISION: Site supervision activity involves the day-to-day supervision of the project, site records and report is made available to the management.
PROGRESS AND SITE MEETINGS: Progressive site meetings are held regularly to evaluate the project’s progress. Representatives of the consultants, contractors must always attend. Agenda for the site meeting includes weather report, progress report and labour report among others.
INSTRUCTION AND VARIATION: Instructions are issued for varied or additional work by the Architect or his representatives as the need arises. It is always in writing for record purpose.
INTERIM CERTIFICATES AND PAYMENTS: This describes the amount due to the Contractor(s) for work done and materials delivered to the site for the project. The client has 14-28days from the date of issuance of a certificate to effect payment to the contractor(s).
COMPLETIONS, DEFECT e.t.c: The conditions of contract spelt out the completion date of the project. Defects liability period usually six months from completion is the period for which the contractor is liable to make good all defects that may occur at the project at own expense.
DELAYS AND DISPUTES: The act of not completing the project at the scheduled date is construed to be a delay. The contractor can request an extension of time for the completion of the project. If the request is granted by the Architect/Project manager, then the contractor will not be penalized. If otherwise, the Liquidated and Ascertained Damages clause of the contract will be enforced. Disputes are referred to as disagreement between contract parties (Client, Architect, Engineers, Quantity surveyors and Contractors e.t.c) Contract management is fundamental to the successful completion of any project. Mutual co-operation is expected from all parties.
Federal Republic of Nigeria Official Gazette (1996),
Electricity Act: Electrical Installations regulations and Electrical Supply Regulations.
Ewesor peter O. (2003), Practical Electrical System Installation work and practice.
Practical power distribution for Industry textbook by Jan de Kock & Kobus Strauss)
Contributor: Orogbemi, Oluwole Olufemi (adopted report)