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. Unless otherwise indicated wiring shall consist of PVC insulated, copper conductor wires installed in heavy gauge steel galvanized conduits.

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

Comply with the General Conditions, Supplementary Conditions and the requirements in various Sections of the Electrical Specification. In addition read and conform to all Electrical Sections of these specifications. The installation shall comprise air networks connected to roof and down conductors and finally terminated in earth electrodes, via structural re-bars and suitable test points in accordance with the details included on the attached drawings or in the Specification Section.

Most Construction projects requires underground cabling system for its power supply, some times High tension system too. The architects and builders are least bothered about how this cables routed to the premises and equipment. If electrical professionals pointed out the feasibility, the aesthetics of the project would touch to the intended level. Hence, in the planning stage itself the routes and size of the power cable trench to be incorporated in the project design.

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

Earthing or Grounding of Diesel Generator Plant is important to ensure correct operation of the plant and safety of the people who work over there. Generator neutral (star point) is to be connected by insulated earthing conductor through the neutral earthing link or device to main earthing bar. Neutral earthing conductor is to be suitably sized to carry maximum earth fault current for time it takes the system protection to operate with final conductor temperature not exceeding 160 deg. C, but not less than 30 mm2 per 100 kVA of generator rating, with a minimum of 50 mm2. All emergency power diesel gensets including portable gensets to be connected to grounding conductor.

Also read: Guidelines for installing emergency power diesel genset.

MV switchgear and MV cables are to have separate main earthing bar connected to framework or earth bar of each item by insulated conductor and the earth-electrode by 2 insulated earthing conductors, one at each end of bar, via testing joints. Earthing conductor is to be minimum 150 mm2.

The scope of work shall cover providing grounding stations, laying copper ground wires and connecting the panels, equipment, etc. to the ground grip as shown in the drawing.

Earth / Ground Station

The ground station shall be as shown in the drawing. The ground electrode shall be minimum 10 feet long 1 inch dia steel pipe with copper weld exterior surface. The ground resistance shall be maintained with a suitable soil treatment as shown on drawings or as discussed and decided at site.

The resistance of each ground shall not exceed 2 ohms.

The ground wire shall be fixed to the rod with a clamp and safety set screws. The clamp shall be permanently accessible. Manholes with proper covers shall be provided.

Ground connections shall be of the bolted type on the top of the rod.

Scope of Work of this this sample specification covers the supply, installation, testing and commissioning of all wiring materials for power and lighting in concealed and/or surface conduits.

1. Applicable Standards

The conduits shall conform to IS 9537 I & II  or equivalent standards. Switches, Plug Sockets shall conform to IS 3854 and IS 4615, however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work.

Method Statement For Installation Of Electrical PVC Conduits And Accessories In The Concrete Slabs, Columns, Block Works And Concrete Walls

1. Introduction and Scope

This method statement explains the detailed requirements and procedures for the installation of PVC Conduits and accessories in the concrete slabs, columns, block works and concrete walls.

Electrical Sub-Main Distribution Boards (SMDB) are the integral part of Electrical LV Power distribution network in the end user premises of a medium and large scale projects. SMDB acts as a mediator between Main Distribution Board (MDB) and Final Distribution Boards (FDB) that serves approximately 100A to 400A load range.

Most electronic systems which are responsible for modern advances are based on digital technology. All digital systems, computers and microprocessors are assembled from simple circuits called logic circuits. The basic building blocks of logic circuits are logic gates. And logic gates themselves are simple electronic circuits comprising of diodes, transistors and resistors.

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.

Construction companies normally submit Payment application every month as per the contract agreement. Until completion of the project, they get part payment from their client after submission of claim which is duly approved and certified by project consultant. Project QS collect all the relevant work details and progress percentage from the field engineers in close coordination with Project Manager.

Vacuum Interrupter (VI) are vacuum sealed-off devices incorporated in Vacuum Circuit Breakers (VCB) to cause interruption of fault currents in medium voltage electrical distribution systems. The contacts of the VI are pressed against each other under normal circuit conditions. In the event of a fault current, the VCB mechanism effects withdrawal of the movable contact from the fixed contact.

Mechanical Pipe work, its Fittings and Valves works described in detail under MEP construction work. It includes pipe erection method, supports both vertical and horizontal, welding, and other fittings and accessories.

Below drawing shows how to install cable tray and its support system. This cable tray support system drawing has Isometric view and cross-sectional view. Following are the steps to be done for laying cables on wall mounted cable tray:

1. Install cable tray support using a pre-fabricated flange or GI channel. The size, length and intervals of the support to be as per the specification, standards, number of cables, and size of the cable.
2. Fix the cable tray as shown on the drawing.
3. Lay the cable keeping the distance as per calculation.
4. Tie the cable using cable tie and label the cables as required.

Lighting Distribution Boards (LDB) are an integral and essential part of every building project and it must be designed, manufactured and installed all in accordance with the safety standards. In most of the cases it operates a layman wherein others operate dedicated or trained person. This article explains what are the essential standards, parts, frame to be applied for manufacturing and installation of lighting distribution boards in a quality building project.

1. Introduction and Scope

This method of statement specifies the detailed requirements and procedures for the installation of Power and Lighting System Wiring.

2. Applicable Project Specification

Section: Cables and wiring

Division: Installation

Sub Division: Subdivision