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.

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.

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.

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.

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 contractor shall supply, install, test and commission the medium voltage switch gears (13.8 KV) as shown and described on the drawings, specification and bill of quantities.

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.

At the completion of the electrical installation works, the entire installation shall be subject to the test before final placing in service under the full responsibility of the contractor. Unless Otherwise specifically called for all tests shall be carried out in conformity with IEE regulations. Contractor shall coordinate with the Client and the Supervising Engineer to get electricity from the local supply authority before starting of testing and commissioning.

A. Protection against Corrosion:

Protect bolted connections against corrosion either hy filling with vaseline or coating with a special anti-corrosion compound and proper capping (Denso tape / grease caps).

Master Antenna Television or MATV means many TV connection outlets from one Master antenna control system. Usually high-rise apartment houses, hotels, schools and cluster based residential area utilizes this kind of TV distribution network. It may or may not include FM radio so that one outlet can receive both TV and FM reception. The scope of this section covers the design, supply, installation, testing and commissioning of Master Antenna TV System, for the reception and distribution of television broadcast signals.

A sample Specification for Electrical Construction Contract Works that describes General Conditions And Requirements to accomplish electrical works all in conjunction with Architectural, Civil, Mechanical and other services.

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.

In electrical projects, both construction as well as maintenance, the following terms used on the Drawings, Specifications and in the actual Work site are equivalent and may be used interchangeably: "earth" and "ground"; "earthing" and "grounding". Besides, this article tries to rectify misinterpretation of some important terms often used by people involved in the electrical earthing / grounding work.

Reliable electrical power becomes one of the most wanted factor in modern world industry where operation should be uninterruptible and maximize the cycle of operation, output quality and to avoid losses and damages. Here we are talking about Automatic Transfer Switches (ATS) also known as Automatic Mains Failure (AMF) panel to cater uninterrupted power supply from Mains or backup sources like Diesel gen-set, static ups etc.

A. Earthing Cables: Separate protective earthing cables for lighting column circuits are to be run with power circuit, terminated at LV supply position in lighting control panel and looped into column earthing terminals. The last column is to be bonded via an earthing bolt to a single 16 mm diameter stainless steel rod, 3.6 m long, driven into ground adjacent to column. Bonding is to be 16 mm2 stranded bare copper conductor.

Electrical Engineers seldom show interest acquiring knowledge and experience on cable tray installations. Most of them think it's a concern of mechanical fabricators to be taken care of it. A proper and professional way of cable tray installation requires good involvement and coordination of people from both electrical and mechanical disciplines. If cable tray system has been installed appropriately in a project, following advantages can be counted:

• Cable Tray system enhances safety of electrical wiring system.
• Cable tray installation provides dependability in any circumstances.
• Cable Tray system saves space, materials, labor, time and cost.
• Maintenance and extension of cable tray installation are easier than any other wiring system.

Hence, electrical installation of a project must give high priority to adopt properly evaluated cable tray wiring system if aesthetic impact is low. This article explains how to make a typical method statement for cable tray or trunking installation for a building project.

Earthing / Grounding work has to comply with the requirements of General and Technical Conditions of the Project including statutory obligations and regulations. Submittals to be approved by project consultant prior execution of the actual work. Regulations and rules of supply authority also to be considered when preparing the submittals for the local in which installation is being constructed.

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.