Choice of Cables Distribution Boards

Choice of Cables Distribution Boards Points : choice of cables distribution boards, basic information on cables distribution boards Choice of Cables There is not much sense in planning a perfect installation on paper and then spoiling it all in practice by installing cheap low quality cables. Within a few months of installing inferior cables, consumers nearly always experience trouble with cables burning out, insulation breaking down, fuses blowing inexplicably, danger of shock whole installation has to be done. In other words, cheap cable is not so cheap after all. Surely the most sensible thing to do in the first place would be to install high quality cables thus saving the cost of a rewire in the near future, and giving the consumer complete confidence in the installation. Details of cables manufactured by Cables Limited are given in this section together with advice for their particular use. Basic Information on Cables The purpose of a cable is to enable power to be transmitted from the supply to a load with maximum efficiency. General wiring cables are manufactured in two voltage grades — low and medium. For a given cable of the same conductor size the insulation for the medium voltage range is thicker than for the low voltage range, in order to withstand the increased voltage. The two grades are termed 25 0/440 volt grade and 660/1100 volt grade. 250/440 volt grade denotes that the cable can be used as a conductor in a system where the voltage to earth is not greater than 250 volts, and the voltage between the conductors is not greater than 440 volts. Thus a 250/440 volt grade cable could be used in d 3 phase 440 volt system having its neutral point solidly earthed. In the same way, 660/1100 volt grade denotes that the cable can be used as a conductor in a system where the voltage to earth is not greater than 660 volts, and the voltage between the conductors is not greater than 1100 volts.