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.
Earth electrode resistance, Insulation resistance of factory-built materials installed at the site and Insulation resistance of site-built materials installed at site to be considered individually for field quality control check. It is further to be monitored earth resistance of individual earth unit and combined resistance of earth units.
Construction projects highly depends on typical installation details and drawings. Architects and engineers use this kind of information to reduce their work load. Employees particularly technicians and foremen who execute the project uses typical drawings as general guidelines where repeated structure, forms, shapes, operations, loads, etc. come into force.
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.
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.
Every project is unique, in particular, construction projects. There are many methods applied to accomplish functioning of individual installations included in the whole project. Building services like Mechanical, Electric, and Plumbing (MEP) work have given more importance than other disciplines dealt with. It's because of complexity and alternate methods available to accomplish the same output. While executing individual installations - also known as tasks - construction team have to adopt suitable methods submitted as an integral part of Tender. Most of the project managers or representatives of client keen to look Method Statement of critical and important tasks. We will look into what is Method Statement and what is the importance a Method Statement brings to a construction project.
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.
What is Automatic Transfer Switch (ATS)?Automatic Transfer Switch (ATS) is an automated switching device that transfers load power to backup power during mains failure and back to its original state when mains power reinstate to the normal condition. It will have its own contacts, microprocessor to analyses the conditions whether power supply is normal or backup and need backup or mains power. Here "back up power" may become either Standby generator or another mains power or static power source like UPS.
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.
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.
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:
- 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.
- Fix the cable tray as shown on the drawing.
- Lay the cable keeping the distance as per calculation.
- Tie the cable using cable tie and label the cables as required.