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.
Earthing or Grounding Electrode for an effective and reliable electrical earthing system requires proper survey and analysis of project location, type of structures installed and electrical / electronic equipment used in the entire system. The design calculation of the earth electrode systems shall be based on the approved earth resistivity data and the system's fault currents and their duration.
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.
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.
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.
Compound Demarcation or separations of compounds may use metallic fences sometimes for saving money or aesthetic reasons. Architects and owner of the project decide whether their property protected by compound wall or it needs only fencing. If fencing considered, most cases it will be metallic fence. In the electrical point of view and as a safety measure, metallic fence shall be separately earthed unless they come within 1.8 m of any equipment or structure above the surface of the ground, which is connected to the main earthing system. If the separation of 1.8 m cannot be obtained the fence shall be bonded to the earthing system. Here is how compound fences connecting to the earthing system.
Audio Intercom System being used in high-rise buildings or commercial complexes, provide two way communication from entrances, gates, go-downs, industrial plant rooms and normal doors, to an internal audio handset. It can be used to screen authorized visitors from outside entrance and useful to communicate internally between persons from one room to another room or office spaces. It can also be used to function as effective public announcement system.
Installation Methods of External, Exterior and Outdoor Lighting System includes lighting equipment luminaires, control gears, panel boards, poles, brackets, cabling, and allied minor civil works. All installations are to be carried out under strict supervision of qualified supervisors and engineers. If installation required heavy vehicles, extreme care has to be taken for preventing damages of lighting equipment, control gears and poles.
What Is Engineering? Engineering is an art of applying science to the optimum conversion of the resources of nature to the uses of humankind. It is based principally on physics, chemistry, and mathematics and their extensions into materials science, solid and fluid mechanics, thermodynamics, transfer and rate processes, and systems analysis. It is thus we must define Engineering: "the practical application of science and math to commerce or industry". In other words "the art or science of applying scientific knowledge to practical problems".
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.
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.
Main earthing bar or loop is to be conveniently located in electrical/mechanical plant rooms, and connected by earthing conductors to exposed conductive parts of motor control centre at its earthing bar, and to motors, switches and other electrical equipment etc. at their earthing terminals, using 20 x 2 mm insulated copper strips or 35 mm2 insulated copper conductor (minimum size) or as required to carry maximum earth fault current for 1 second with final conductor temperature not exceeding 200 deg. C (392 deg. F).
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.
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.
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.
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.