Electric Power Supply and Lighting Systems inside Your Home
Electricity as a form of energy has been a life necessity ever its discovery by Benjamin Franklyn, whom all consider as the father of electricity. Ever since its discovery, electricity has been a major component in other scientific inventory such as the electric dynamo, a modern power generator whom Michael Faraday invented in 1831. This invention opened the door to the new era of electricity. A few decades later, in 1879, Thomas Alva Edison (see Fig3) invented the first light bulb (see Fig2) in October 22, 1879 and it lasted for 13.5 hours. In 1879, Thomas Alva Edison formed the Thomas Alva Edison Electric Company. Ever since then, Electricity has been a major significance in human existence.
In Hong Kong, electric current voltage is 220 volts, with a frequency of 50Hz (Hertz), electricity is generated by two power utility companies; the Hongkong Electric Company Ltd (HEC) which supplies electricity to Hong Kong island, Ap Lei Chau and Lamma Island; And CPL Power Hongkong Ltd and Castle Peak Power Company Ltd (CAPCO), which both supplies electricity in Kowloon, the New Territories and most of the outlying islands. Electricity is generated in areas remote to urban areas, for environmental reasons, and transmitted trough transmission lines.
Fig1: Shows how electricity is transmitted from the source generator to its end consumer.
Fig2: the first light bulb invented by Edison Fig3: Thomas Alva Edison
Types of Incoming Power Supply
There are three types of incoming power supply transfer available. Transfer is determined by the electricity demand of a consumer and the availability and capacity of the supplier to transmit electricity in return. Low Voltage Cable Supply is usually employed when customer demand is low. Mainly employed on home use; 11KV Incoming HV Cable and LV Supply is employed when demand is high. Usually used in commercial establishments which electricity demand is high; and 11KV Incoming Supply is employed in hospitals and other facilities where electricity consumption is extremely high and/or security of power supply is necessary.
Electrical Safety
Every established either home or commercial that consumes electricity should comply in accordance to the Supply Rules and Electricity Ordinance in order ensure safety in the consumers part. A main switch room should be made available; this is where the main switch board (see Fig4) is located; and where the direct electricity from the supplying company goes. By these means regulation on electric flow through the whole area can be observe. It is also a safe way to avoid fire incidents that are sometimes due to electricity.
Some points to consider in a main switch room are the position or the location of the room. It should easily be located; it should be accessible at all times; with an exit with an outward opening door should be provided; it should be big enough in order to accommodate all the associated main switch boards; no there should be no drainage and water pipe system in the room to avoid short circuit and incident of being electrocuted; proper ventilation and illumination should also be provided so incase of main power failure, Emergency lights to be provided should be capable in 30 minutes operation, proper ventilation should be provided in order to prevent over heating.
A switchboard is composed of different switches, fuses, and/or circuit breaker, which provide switching and protection to the number of circuits which are connected to the main source; and these are enclosed in a metal structure. It is an electrical system, that’s provides adequate protection to prevent shortage, and converts large electrical current into small one. Normally, the main switchboard id divided into certain number of different panels, each of which accommodates certain equipments. It controls all devices by means of insulated control panels.
Fig4: sample photo of a main switch board, control panel and fuse commonly use.
Fig5: sample of a circuit breaker and other breaker available in the market.
Types of Electrical System
There are different types of electrical system that can be installed in home or other facilities. The type of system to be installed depends on the facility; because some are too complex, it will not be appropriate for home usage. But still proper electrical system provides safety and additional security in general.
Insulated conduit and Trunking System in this type of system is consists of insulated conductors which are protected by non-metallic conduits and trunkings (see fig5). The material used for making the conduits and trunkings is usually polyvinyl chloride. This type of system is easy to install, has a high resistance against corrosion, and is impervious to most chemicals, it is also weatherproof and does not support combustion. This system can normally operate within the temperature range of 15oC to 65oC. But this system cannot withstand mechanical strains
Metallic Conduit and Trunking System is similar to the insulated conduit and trunking system except that metal instead of PVC materials is used. The kinds of metal used can be galvanized steel, aluminum or copper. In such system, a single core insulated cables are enclosed to a metal conduits. This system has the advantage of a high degree of mechanical protection, it can minimization fire risks, and provides efficient continuity, and it allows easy re-wiring if further improvement should be done. These systems are widely used in electrical installation and installed at high level or at the ceiling (see fig4, fig7, fig8).
Busbar Duct System (see Fig9) uses copper or aluminum busbars (see Fig10) mounted on insulators, and are enclosed in steel trunking to convey electrical wirings. Provision is made for fuse or circuit breaker to allow circuit tapping given at appropriate intervals by the bus-bar duct system. This system is convenient to use where large currents have to be conveyed, this system offers considerable flexibility when it comes to electrical installation before the sub-circuit arrangements are finally made. There are two types of Busbar Duct System the Vertical Rising Mains and the Overhead Busbar System. The vertical rising system is often installed in a multi-storey building. By power distribution, the incoming current is connected to the bottom of the rising main and a suitable tap-off point is provided at each floor. In the event of fire, hot gases and flame would tend to travel up, so it is essential that fire proof barriers are fitted at each floor level. A typical fire barrier is consists of a 50-75mm thick layer of glass wool and supported by a hard durasteel board that completely fills the entire trunking. The busbar that passes through this barrier must be fitted with insulating sleeves to provide additional protection. On the other hand, the Overhead Busbar System provides a more convenient method of power distribution in factories or large workshops. A typical Overhead busbar system has plug-in tap-off points at 1m interval into which fused tap-off boxes can be fitted to provide electric flow manageability. Thus, it becomes easy to provide a supply position wherever it is required and the position of the supply points can be readily and easily changed if needs arise. Example: more power is needed in a certain department of a factory, the power in the other department can be easily tap-off , and that power can be easily transfer to the department in need.
Underfloor Trunking System (see Fig11) is more economical and practicable electrical system to install. Networks of cableducts in the solid concrete floors are provided during the construction of the building, these cableducts (see Fig12) are used to accommodate the electrical wires, telecommunication cables, and fire alarm cables. The underfloor trunking system often takes the form of an intersecting grid so that every part of the floor area will be accessible when the wirings are made. Several ducts with separate compartments are used to accommodate wires for the various purposes. Holes with removable pressed steel cover are also provided at intervals for floor outlets/sockets (see Fig13) and adaptors for conduit.
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New and Renewable Energy
The term “New and Renewable Energy”, refers to energy sources other than the traditional sources such as fossil fuels which can either be oil, gas, or coal; and atomic energy; which constant use can be environmentally harmful. Such energy resources such as solar energy, wind energy, geothermal energy, biomass, natural gas and hydrogen are sources of renewable energy. If energy consumption continues to increase at existing level in the years to come, the projected carbon dioxide emission for the year 2010 can reach to 39%. Effective use of this renewable energy source will help Hongkong reduce greenhouse gas, arising from the usage of fossil fuels.
Electricity generation in Hong Kong has produced an after effect; air pollution that is threatening our health began to arise. It has also contributed on significant amounts of greenhouse gas emissions, which contributes to global warming and sudden climate change, the single biggest threat to our planet and of biodiversity.
Energy is something everyone should learn how to conserve. Its current abundance doesn’t mean that it will not eventually run out. Peoples demand for electricity is constantly getting higher as the time passed. In a developed country like Hongkong where energy is a necessity in living; not just in Hongkong but the world; and especially in Mainland China, where population has been steadily growing. A call for energy conservation should be done. Increasing number in population means an increasing demand in energy consumption. With China’s increasing energy demand, expanding its renewable energy market should be done and technology improvement must push trough for further improvement. Hongkong; as a Special Administrative Region of China; could play an active role in this movement; by being an information and technology gateway and also by serving as a financial intermediary for China. Both Mainland China and Hongkong will benefit from promoting renewable energy for both countries. This task will both be challenging but at the same time full of opportunity for Mainland China, Hongkong and other parties involved. The result of this action will have a long term implication to the world’s energy conservation. However, sustained effort, proven policies, and support from both the people and the government are needed in order to over come all the obstacles and constraints that shadow this movement.
Credit:ivythesis.typepad.com
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