Basic Electrical Installation Work

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20 2.10 1 36.5 24.387 0.454 2.49 6 7.28 Reproduced from the IEE Site Guide kind permission the Institution Electrical Engineers.87 35 1.91 10 3.5 10.82 25 0.5 14.557 – 25 1.10 1.20 1.114 1.674 2.66 16 1. Ω The total earth fault loop impedance therefore: ZS 702 202 .51 2.Overcurrent, short circuit and earth fault protection 249 Table 12.727 1.5 7.78 35 1.877 – 25 1.41 2.08 6 2.5 30.5 16.5 1.64 50 1.524 0.16 10 1.02 4 9.23 – 16 2.30 3. Ω.774 1.44 10 4. this case the factor 1.5 2.15 1.69 6 6.51 2.20 and therefore the cable resistance under fault conditions will be: 0 585 702 .91 16 4.20 1.51 50 0.71 4 2.98 – 16 2.83 10 6.5 25. given Table the Site Guide.61 4 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 18.5 12.74 50 0.40 35 0. .5 1.22 6 3.5 12.251 2.20 25 2.5 19. .048 1.911 1.07 35 1.84 50 0.82 4 4