Basic Electrical Installation Work

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20 1.87 35 1.454 2.20 25 2.16 10 1.911 1. this case the factor 1.5 10.5 19.41 2.84 50 0.98 – 16 2.66 16 1.5 14.08 6 2.877 – 25 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 12.5 24.51 50 0.91 10 3.51 2.02 4 9.387 0.15 1.5 25.22 6 3.51 2. Ω.69 6 6.28 Reproduced from the IEE Site Guide kind permission the Institution Electrical Engineers.44 10 4.5 2.5 1.048 1.5 12.524 0.07 35 1.5 30.71 4 2.82 4 4.774 1.251 2.78 35 1.61 4 1.5 1.82 25 0.74 50 0.10 1.5 16.114 1.40 35 0.20 2.10 1 36.64 50 1.30 3.83 10 6.20 1.20 and therefore the cable resistance under fault conditions will be: 0 585 702 .49 6 7. given Table the Site Guide.557 – 25 1.Overcurrent, short circuit and earth fault protection 249 Table 12.727 1. Ω The total earth fault loop impedance therefore: ZS 702 202 .91 16 4.23 – 16 2. .5 7. .674 2