Electrical wiring needs expertise attention to every building projects. It directly related to the safety of human beings and utilities / equipment people handle. The scope of electrical wiring shall cover supply, installation, testing and commissioning of all conduits and accessories, wiring, switches, socket outlets, spur outlets, junction boxes / pull boxes, GI pull wires, ceiling roses making connections etc. This Electrical Construction Article gives comprehensive details of various installation methods, materials used in each installation methods used in building construction projects.

Method of Earthing To Main Distribution Board (MDB)

Main earthing bar is to be provided in main distribution room and connected to earth electrode by 2 insulated conductors (minimum 150 mm2) via testing joints. Earthing bars of main distribution boards are to be connected, by insulated earthing conductor, directly to main earthing bar at main distribution room.

Special areas like Airports, Port Trusts, Naval Base, Military base, Telecom buildings, Refinery, Petroleum handling areas etc. needed highly sophisticated security and access control system. It provides safety and security for both men and equipment the area handling. Here is the specification and installation methods for SACS.

This article explains electrical power cables used in construction works complete with supply, installation, testing and commissioning of High Voltage (HV) and Low Voltage (LV) cables. All cables shall conform to standards of IS 7098-1973, IS 1554-1976 and wiring cables to IS 694-1977 however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work.

Occasionally Main Contractor of the construction work depends sub-contractor for accomplishing some smaller or part of the project that may require specialized technical know-how and installation methods. In those cases Main contractor selects some sub-contractors who has capacity to achieve the task within the given time frame. Hence both of the parties, ie., Main contractor and Sub-contractor to be signed an agreement which protects both the parties' interest. Here is a sample for Conditions of Sub-contract Agreement in Construction Works.

Component parts of earthing system are to include the following:

1. Earth electrode (rods, tapes etc.)
2. Main earthing terminals or bars
3. Earthing conductors
4. Protective conductors
5. Equipotential bonding conductors
6. Electrically independent earth electrodes for special systems (clean earth)
7. Accessories and termination fittings, bonding, welding kits and other materials

Continuity: Ensure that complete earthing system is electrically continuous and mechanically secure. Locations of main earth bars in substations, electrical rooms, mechanical rooms, hub (Technical) rooms, etc., to be clearly identified by 100mm X 100mm white traffolyte labels, with red lettering, to Engineer's approval.

Busbar Trunking System (BBT) in electrical construction, uses to transporting electrical power to a shorter distance but many utilization point, say, within the building or a compound of facilities. Though cables can also be used in these areas, their economic impact would be high if compared to the effective Busbar Trunking System. It will help us to tap power directly from where we want it to be and make utilize to the service point.

This specification intended to supply, install, test and commission mineral oil immersed 1500 KVA, 3 phase indoor transformers, fitted with cable boxes, bolts, and all necessary accessories. Transformers shall be indoor type, oil filled, two winding, four off load capacity, 2.5% taps, two above and two below high voltage rating in compliance with IEC 76 or BS 171.

Fire Alarm System installation work covered by this section of the specifications includes the furnishing of all labor, equipment, materials, and performance of all operations in connection with the whole Fire Alarm System as shown on the drawings and as herein specified. The requirements of the conditions of the Contract, Supplementary Conditions and General Requirements apply to the work specified in this section.

The metallic sheath and armour of multicore cables shall be bonded together and earthed.

Cable earthing conductors shall be copper strip with appropriate section laid in formed cable trenches or ducts, or fixed to walls, concrete or steel work, by means of clamps or claw type cleats, appropriately secured into suitable wall plugs or tapped holes. The spacing of fixings shall not be greater than 1 m. Where earth strip is buried or laid in positions in which there is danger of corrosion it shall be provided with a corrosion-proof serving of extruded thermo-plastic or self-adhesive PVC tape which for short lengths may be hand applied on Site.

We often depends Diesel Electrical Genset as emergency power system due to mains failure. As a professional, the installation of diesel electrical power generator should be as per the clients requirement and to be inline with the authoritative norms and standards. Safety, security, convenience, future expansions etc are to be considered and co-ordinated before start detailing of the genset's installation. The generator should be as close to the main change-over board as possible. In cases like Textile Mills, where there is fear of smoke affecting the quality of the yarn etc., generators may be located away from the Plant / Department.

In this sample MEP specification section, Mechanical Ductwork, Grilles And Diffusers have been described in detail under construction contract work.

Main Highlights of this MEP Specification

1. Mechanical Ductwork
2. Mechanical Ductwork Supports
3. Mechanical Dampers - General Requirements
4. Flexible Joints for Mechanical Ductwork
5. Air Intakes and Outlets
6. Kitchen Extract Canopies
7. Kitchen Extract Air Ductwork
8. Access Doors
9. Ductwork Test Points
10. Ductwork Protection
11. Grilles
12. Diffusers
13. Sand Trap Louvres
14. Air Valves
15. Fire Dampers

Fire alarm systems have become increasingly sophisticated and functionally more capable and reliable in recent years. They are designed to fulfill two general requirements: protection of property and assets and protection of life. As a result of state and local codes, the life-safety aspect of fire protection has become a major factor in the last two decades.

Low Voltage Switchgear are familiar to every people since they are the controlling mediators between low voltage utilities and equipment with human beings. Be it a common home DB or an isolator or control centres, they all are being manufactured to use untrained people ie., common people. The scope of works shall cover the supply installation, testing and commissioning of main and sub-distribution boards, panel boards, fusible safety switches, circuit breakers etc. Associated minor building works require for the erection of the distribution boards and panels shall be included in the scope of work.