Good cross section of earthing conductors according to IEEE Std 80-2000 Therefore, when steel in concrete is connected to steel in soil, a driving galvanic voltage of approximately 1 V causes a corrosion current to flow through the soil and the wet concrete and dissolve steel in soil.Įarth electrodes in soil should use copper, copper coated steel or stainless steel conductors where these are connected to steel in concrete.
#ELECTRICAL EARTHING CALCULATION SERIES#
Steel in concrete has approximately the same galvanic potential in the electrochemical series as copper in soil. (…) A further problem arises from electrochemical corrosion due to galvanic currents. This type of arrangement comprises either a ring earth electrode external to the structure, in contact with the soil for at least 80% of its total length, or a foundation earth electrode. (…) The type B earth-termination system is preferred for meshed air-termination systems and for LPS with several down-conductors. Still the most important measure is equipotential bonding. The resistance value should be as low as possible in every case but especially in the case of structures endangered by explosive material. The recommended value of the overall earth resistance of 10 Ω is fairly conservative in the case of structures in which direct equipotential bonding is applied. Hence the LPS designer and the LPS installer should make special provisions for protection against dangerous step voltages in the vicinity of the earth-termination networks if they are installed in areas accessible to the public (see Clause 8). (…) The LPS designer and the LPS installer should select suitable types of earth electrodes and should locate them at safe distances from entrances and exits of a structure and from the external conductive parts in the soil, such as cables, metal ducts, etc. Good earthing (grounding) system according to IEC/BS EN 62305-3:2011 standard
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