Basic Electrical Installation Work

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02 4 9.69 6 6.15 1.71 4 2.08 6 2.07 35 1.64 50 1.28 Reproduced from the IEE Site Guide kind permission the Institution Electrical Engineers. Ω The total earth fault loop impedance therefore: ZS 702 202 .30 3.91 10 3. Ω.61 4 1. given Table the Site Guide.78 35 1.251 2.10 1 36.5 10.727 1.1 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 18.20 1.87 35 1.51 2.5 25.5 12.5 1.49 6 7.74 50 0.98 – 16 2. this case the factor 1. .22 6 3.91 16 4.20 1.877 – 25 1.82 4 4.51 50 0.20 2.44 10 4.23 – 16 2.10 1. .82 25 0.Overcurrent, short circuit and earth fault protection 249 Table 12.66 16 1.5 2.83 10 6.774 1.41 2.911 1.387 0.5 19.5 7.5 1.16 10 1.40 35 0.5 30.114 1.20 25 2.5 12.20 and therefore the cable resistance under fault conditions will be: 0 585 702 .51 2.5 14.454 2.5 24.674 2.557 – 25 1.84 50 0.524 0.5 16.048 1