earth electrodes BS 7671
Post by: Omega delta electric
BS 7671 recognises a wide variety of types of earth electrode. regulation 542-02-01 lists the types recognised which incloude earth rods, earth plates and underground structural metal work.
the soil resistivity of the ground is probably the single most important factor in the determination of the type of earth electrode. rods can only be as effective
as the contact the make with the surrounding material. thus, they should be driven into virgin ground, not disturbed (backfilled) ground. where it is necessary to drive two or more rods and connect them together to achieve a satisfactory result, the separation between rods should be at least equal to their combined driven depth to obtain maximum advantage from each rod. in some locations low soil resistivity is found to be concentrated in the topsoil layer, beneath which there may be rock or other impervious strata which prevents the deep driving of the rods, or a deep layer of high resistivity. only a test or known information. in such circumstances, the installation of copper earth tapes, or pipes or plates, would be most likely to provide a satisfactory earth electrode resistance value.
BS 7671 recognises a wide variety of types of earth electrode. regulation 542-02-01 lists the types recognised which incloude earth rods, earth plates and underground structural metal work.
the soil resistivity of the ground is probably the single most important factor in the determination of the type of earth electrode. rods can only be as effective
as the contact the make with the surrounding material. thus, they should be driven into virgin ground, not disturbed (backfilled) ground. where it is necessary to drive two or more rods and connect them together to achieve a satisfactory result, the separation between rods should be at least equal to their combined driven depth to obtain maximum advantage from each rod. in some locations low soil resistivity is found to be concentrated in the topsoil layer, beneath which there may be rock or other impervious strata which prevents the deep driving of the rods, or a deep layer of high resistivity. only a test or known information. in such circumstances, the installation of copper earth tapes, or pipes or plates, would be most likely to provide a satisfactory earth electrode resistance value.
whatever from an earth electrode takes, the possibility of soil drying and freezing, an of corrosion, must be taken into account. preferably, testing of an earth electrode should be carried out under the least favourable conditions, i.e. after prolonged dry weather. further information on earthing principles and practice can be found in BS 7430 : 1998 'Code of practice for earthing'.
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