Basic Electrical Installation Work

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1.1. Ci the correction factor used when cables are enclosed thermal insulation.50 NA .725 correction factor applied when semi-enclosed fuses pro- tect the circuit described item 5.87 0.2).61 0.1 Ambient Temperature Correction Factors. Cg the grouping correction factor given Tables 4C1 4C5 the IEE Regulations and Table the Site Guide.Electrical installations and wiring systems 299 The cable rating must chosen comply with Regulation 433. ● Where the cable totally surrounded over short length, the appro- priate factor given Table 52.0 0.94 0. ● Where the cable totally surrounded over length greater than 0.6.79 0. Adapted from the IEE Site Guide Kind Permission the Institution Electrical Engineers Table 4B1 IEE Regulations Correction factors for ambient temperature where protection against short-circuit and overload Type of insulation Operating temperature Ambient temperature (°C) 25 65 Thermoplastic (general purpose PVC) 70°C 1. The cor- rection factors which may need applying are given below as: Ca the ambient surrounding temperature correction factor, which is given Tables 4B1 and 4B2 Appendix the IEE Regulations. Table 14. the calculated value greater than this value, the next larger cable size must tested until cable found which meets both the cur- rent rating and voltage drop criteria.1.5.03 1.71 0. Note: cable should preferably not installed thermal insulations. They are also shown Table 14.6 gives three possible correction values: ● Where one side the cable contact with thermal insulation we must read the current rating from the column the table which relates reference method (see Table 14. Having calculated the cable rating, the smallest cable should chosen from the appropriate table which will carry that current. This cable must also meet the voltage drop Regulation 525 and this should calculated as described earlier.1 the preface Appendix of the IEE Regulations. When the calculated value less than for lighting and for other uses the mains voltage the cable may considered suitable. Cc the 0. Regulation 523.2 the IEE Regulations Table of the Site Guide should applied.5m must apply factor 0