Furse Earthing & lightning protection

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Vydal: ABB s.r.o.

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Conductors for earthing systems For below ground earthing applications offer a large range bare copper tape, solid circular and stranded conductors thus offering the designer the system the correctly rated conductor without the need oversize.1 23.2 24. An earth conductor must capable carrying the maximum expected earth fault current and leakage current likely occur structure.1 25 100 17.4 15. 19 — Earth conductors .5 126 22.5 37.1 11.4 40. These conductors provide either the connection to final earth electrode (earth rod plate), or the earth electrode itself (earth grid ring earth arrangement).2 20.1 25 1.1 12.0 20 10.9 38 114 20.6 10.5 5.4 15.6 3.5 50 350 61.4 15.6 6.2 25 150 26.S. The size minimum cross-sectional area of the conductor must therefore gauged in accordance with these criteria.5 31.2 7.1 30 120 21.6 35.8 9.3 40 200 35.4 50 150 26.2 16. (mm2 ) kA for 1 Sec kA for 3 Sec 20 1.6 25 8.2 12.6 38 190 33.4 9.5 6.2 31 16.8 30.A.2 30 15.2 45.8 5.2 50 200 35.7 These conductor ratings are based upon the recommendations 7430 with initial conductor temperature 30°C and maximum temperature 250°C.8 31 186 32.5 50 400 70.2 30 150 26.3 50 250 44.4 50 300 52.4 19.0 25. Copper conductor recommended following BS 7430, aluminium should not installed in contact with soil, nor damp areas, and should not used make the final connection to an earth electrode.2 40 160 28.8 25 13.3 40 240 42.6 75 450 79. A good earth conductor must also: • able withstand mechanical damage • compatible with the material the earth electrode • Resist the corrosive effect local soil conditions Furse conductors effectively meet these requirements and are available range sizes to meet differing current ratings (see table left).3 3.1 12.3 38 228 40.2 40 120 21.CONDUCTORS Conductor Size (mm) C.2 20.7 18