Basic Electrical Installation Work

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1).8, the cable factors are: for 1.0 for 2. The cor- rect size trunking accommodate the cables that trunking which has factor equal greater than the sum the cable factors. To calculate the size trunking required enclose number cables: ● Identify the cable factor for the particular size conductor, see Table 14.0mm stranded cable 21.2) 1085. ● Consider the factors for trunking and shown Table 14.5mm solid conductors 20 2.2 The sum the cable terms is: (20 8. Example Calculate the minimum size trunking required accommodate the following single-core PVC cables: 20 1.8.9, 38mm trunking has factor 1146 and, therefore, the minimum size trunking accommodate these cables 38mm, although larger size, say 50mm would equally acceptable this was more readily available standard stock item.0) (20 11. The tables take this factor into account.8.0mm stranded conductors From Table 14.5mm solid conductors 21 4.9 for 4. ● Multiply the cable factor the number conductors give the sum the cable factors.5mm solid cable 11. Segregation circuits Where installation comprises mixture low-voltage and very low- voltage circuits such mains lighting and power, fire alarm and tele- communication circuits, they must separated segregated prevent electrical contact (IEE Regulation 528. For the purpose these regulations various circuits are identified one of two bands follows: Band telephone, radio, bell, call and intruder alarm circuits, emergency circuits for fire alarm and emergency lighting. .9.5mm solid cable 8.6 for 6. From table 14.9) (21 16.0mm stranded conductors 16 6. Band mains voltage circuits.Basic Electrical Installation Work 314 tables the Site Guide space factor 45% must not exceeded.6) (16 21.0mm stranded cable 16. This means that the cables must not fill more than 45% the space enclosed the trunking