BS 7430:1998 Code of Practice for Earthing by The Stationery Office

By The Stationery Office

Show description

Read Online or Download BS 7430:1998 Code of Practice for Earthing PDF

Similar geology books

Eruption of Soufriere Hills Volcano

The andesitic dome-building eruption of the Soufriere Hills Volcano wreaked havoc at the small Caribbean island of Montserrat. approximately 1/2 this 'emerald Isle' was once rendered barren and uninhabitable, virtually two-thirds of the unique inhabitants needed to depart, and 19 lives have been misplaced, all as an immediate results of the volcanic job.

Carboniferous Geology of the Eastern United States

Concerning the ProductPublished by way of the yankee Geophysical Union as a part of the sector journey Guidebooks sequence. This guidebook used to be ready for a box journey to be carried out ahead of the graduation of the twenty eighth overseas Geological Congress, convened in Washington, DC, July 1989. the aim of this box journey is to ascertain the geologic elements that managed the deposition of Carboniferous rocks within the Illinois and Appalachian basins, with emphasis being put on basinal tectonic evolution, sedimentation, and paleoclimate.

Additional info for BS 7430:1998 Code of Practice for Earthing

Sample text

BSI 05-1999 14 Selection of an earthing conductor and connection to an electrode Selection of the material for an earthing conductor should take into account compatibility with the material of the earth electrode and, for a conductor installed in the ground, the corrosive effect of the soil. Information provided in clause 11 for electrodes is relevant to bare earthing conductors also. Aluminium or copper-clad aluminium conductors should not be used in contact with soil or in damp situations and in any case should not be used to make the final connection to an earth electrode.

BSI 05-1999 A calculated value of electrode resistance can be expected to be of only limited accuracy because of uncertainty as to the true value of soil resistivity and its homogeneity. Soil resistivity is dependent on moisture content and temperature as well as on soil constituents, so that it can vary seasonally and progressively due to hydrological trends such as changing water tables or continuous drainage. It is therefore advisable to check the resistance of an electrode both on installation and at regular intervals thereafter.

An accuracy of 2 % is more than adequate, and accuracies of the order of 5 % are usually quite acceptable. The best method of measurement is illustrated in Figure 11. A measured current is passed between electrode X, the one being tested, and an auxiliary current electrode Y. The voltage drop between electrode X and a second auxiliary electrode Z is measured and the resistance of the electrode X is then the voltage between X and Z divided by the current flowing between X and Y. The source of current and the means of metering either the current and voltage or their ratio are often, but not necessarily, combined in one device.

Download PDF sample

Rated 4.94 of 5 – based on 14 votes