resistance to earth of a plate R in ohms (code of practice earthing history First published as CP First published as BS BS Code of practice for protective earthing of electrical installations. 16/22 Total Solution to Earthing & Lightning Protection | 9AKKA Technical BS Code of practice for protective earthing of electrical.
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Measurements and Calculations Of Earth Electrode Systems (BS ) | EEP
The resistance to earth of a given electrode depends upon the electrical resistivity of the soil. Who is this standard for? The value of resistance required might not always be amenable to an automatically set value. The content is copyrighted to EEP and may not esrthing reproduced on other websites.
Soil temperature has some effect on the upper layers of strata, but is only pravtice under frosty conditions. It is important that consideration is given to the possibility of corrosion of the metalwork reinforcement.
Customers who bought this product also bought BS EN This connection should have a resistance not greater than that required to operate safety mechanisms to isolate the electricity supply from a fault situation. The effect of shape on an electrode resistance is related to the current density around the particular electrode considered.
Take the smart route to manage medical device compliance. System earthing involves the provision of a connection to the general mass of earth. Professional in AutoCAD programming.
Soil resistivity may be measured in a similar manner to the establishment of the resistance of the earth electrode. The connecting strip to practixe above ground disconnection point should be fully insulated to avoid electrolytic action.
The resistance R should be taken as the ratio of the voltage between the inner electrodes and the current between the outer electrodes. This website is best viewed with browser version of up to Microsoft Internet Explorer 8 or Firefox 3.
It is therefore important to recognize this issue if a long horizontal practive or bare cable is being considered for producing a low earth resistanceeven though the impedance will ultimately be limited to a final value see Figure 4. After construction and with the passage of time this moisture content will approach equilibrium with that of the soil, and will usually be dryer than when first laid.
Effective earthing safeguards people from the risk of electric shock. Other shapes are not covered here. The resistance to earth of concrete encased steelwork or of concrete reinforcing bars varies according to the type of soil, its moisture content, and the design of the foundation.
The resistivity so determined applies to an electrode separation distance a, which is related to the depth of investigation. However, onsite resistivity testing should always be carried out prior to carrying out an earth system design and installation.
If possible, it is advantageous and recommended to measure the resistance of several such footings to gain an indication of the likely variation of resistance.
You may experience issues viewing this site in Internet Explorer 9, 10 or The majority of the formulae presented in this section relate to low frequency currents and high frequency examples are not included.
This is lower than some types of soil. Earthing systems should consist of copper conductors, copper clad or austenitic steel rods of appropriate dimensions, cast iron plates, or steel piles used individually or connected together in combination to form a single local earth electrode system. Second important characteristic of earthing connection is that it MUST be capable of carrying the maximum expected fault current.
Thus a pipe rod or strip has a much lower resistance than a plate of equal surface area. Where the plate is placed in a cut out slot, e. It is of particular relevance to: The finished joint should be covered with a heavy coat of bitumen.
This requires careful assembly during installation to ensure that the bottom of the plate is resting in the medium used and not on the chalk or high resistivity substrata. By repeating the measurement with increasing values of a, the apparent resistivity involving greater depths may be assessed.
Table 1 gives examples of resistivity only. Connections to the plate should be by copper conductor, welded, riveted or otherwise attached with material that will not cause corrosion at the joint.
Where the structure is supported on many similar footings, it may be considered feasible and more satisfactory to measure the resistance of one footing before it is electrically connected to othersand before there are any other electrically paralleled footings close by.
This is one of the best design reference i have seen. Overview Product Details What is this standard about?
The products of corrosion occupy a greater volume than the original metal and cracking might occur. In high resistivity locations or on rocky ground where long term performance is required, it may be considered necessary to utilize a conductive concrete to improve earth contact resistance around an earth rod or strip tape where applicable. There are commercially available materials to achieve this effectively, but care should be taken to understand how they work during installation to ensure that they remain in contact with the rod or strip and do not shrink or swell away after drying out.
Therefore any part of an electrode system which is less that 0. This should include the size and shape of the earth conductor, the resistivity of the soil in which it is buried and the connection of the system to it.