Basic Electrical Installation Work

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5 30.911 1.30 3.22 6 3.84 50 0. .5 7.66 16 1.98 – 16 2.5 1.08 6 2.91 10 3.51 2.454 2.51 2. Ω The total earth fault loop impedance therefore: ZS 702 202 .10 1.5 25.674 2.78 35 1.64 50 1.87 35 1.387 0.877 – 25 1.41 2.61 4 1.727 1.69 6 6.20 25 2.048 1.82 25 0.5 12.5 19.5 10.251 2.44 10 4. Ω.82 4 4.10 1 36. .5 16.15 1.5 24.16 10 1.557 – 25 1.20 1.20 2.20 and therefore the cable resistance under fault conditions will be: 0 585 702 .51 50 0.02 4 9.91 16 4.83 10 6.5 12.Overcurrent, short circuit and earth fault protection 249 Table 12.20 1.524 0.07 35 1.5 2.71 4 2.5 1.23 – 16 2.28 Reproduced from the IEE Site Guide kind permission the Institution Electrical Engineers.114 1. given Table the Site Guide.74 50 0.40 35 0.1 Table the IEE Site Guide: Value Resistance/Metre for Copper and Aluminium Conductors and per Metre 20°C in Milliohms/Metre Cross-sectional area (mm2 ) Resistance/metre (R1 R2)/ metre (mΩ/m) Phase conductor Protective conductor Copper Aluminium 1 18. this case the factor 1.49 6 7.774 1.5 14