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Earth/ground measurement guide

Earth/ground measurement guide
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Earth/ground measurement guide Earth/ground resistance and soil resistivity testers

About the Chauvin Arnoux Group Founded in Paris, France in 1893, CHAUVIN ARNOUX has spent the centuries since then developing its expertise in the design, manufacture and marketing of measuring instruments for professionals. From handheld instrumentation to fixed electrical equipment and energy performance systems, and from control of the entire thermal process chain to industrial metrology, the CHAUVIN ARNOUX Group's offering meets every customer requirement across all the sectors (selfemployed electricians, industry, government bodies, etc.). A Few Figures • 10 subsidiaries worldwide •...

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Earth/ground measurement guide Earth/ground* resistance measurement One of the basic prerequisites for guaranteeing safety on any residential or industrial electrical is to provide an earth electrode. If there is no earth/ground electrode, people's lives may be endangered and electrical installations and other property may be damaged. An earth/ground electrode alone, however, is not enough to guarantee total safety. Only regular inspections can prove that the electrical installation is operating correctly. There are many earth resistance measurement methods available, depending on the type...

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Earth/ground measurement guide For example, the correlation between the earth resistance and the RCD rated current is specified by the NF C 15-100 standard, as shown in the following table: Maximum resistance of earth electrode according to RCD rated current Maximum rated current of RCD (I∆n) Maximum resistance of earth electrode for chassis earths (Ohms) Medium sensitivity High sensitivity * To simplify, we will use the term "earth" in the text that follows. What is an earth electrode made up of? ›› The earth electrode There are various methods for setting up an earth electrode, depending...

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Earth/ground resistance an soil resistivity testers Soil resistivity Why soil resistivity measurements are useful Soil resistivity (ρ) is expressed in Ohm x metres (Ω.m). This corresponds to the theoretical resistance in Ohms of a cylinder of earth with a cross-section area of 1 m2 and a length of 1 m. By measuring it, you can find out how well the soil conducts electric currents. So the lower the resistivity, the lower the earth electrode resistance required at that location. Soil resistivity measurements help you to: Resistivity varies significantly according to the region and the type of...

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Earth/ground measurement guide Where: ρ: is the resistivity in Ω.m at the point located under point 0, at a depth of h = 3/4a a: is the measurement base in m R: is the value (in Ω) of the resistance read on the earth ohmmeter For these measurements, EDF recommends that distance "a" should be at least 4 m. E(X) Note: the terms X, Xv, Y and Z correspond to the former naming conventions used for the E, Es, S and H electrodes, respectively. ›› Schlumberger method Measurement principle The Schlumberger method is based on the same measurement principle. The only difference concerns positioning of...

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Earth/ground resistance an soil resistivity testers Example of resistivity mapping Depth investigated In the example above, it will be easier to achieve a minimum earth/ground resistance value if the earth/ground system is set up at a depth where the resistivity rho is minimum on several axes of analysis. Methods for measuring earth resistance on an existing earth electrode Earth resistance measurements on installations with a single earth electrode It is important to point out that the earth resistance measurement of reference is the 2-stake method. This method is referenced in all the...

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Earth/ground measurement guide For correct measurement, the "0 V potential auxiliary electrode" must not be set up in the zones of influence of the earths E & H caused by the current (I) flowing. Statistics from the field have shown that the best method for ensuring high measurement accuracy is to place stake S at a position 62 % of the distance from E on the straight line EH. You then need to make sure that the measurement does not vary or only varies slightly when stake S is moved by ± 10 % (S’ and S”) on either side of its initial position on the line EH. If the measurement does vary, it...

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Earth/ground resistance an soil resistivity testers S(Y) (2nd measurement) Earth electrode to be tested E(X) This may lead to an excessively high earth resistance value later on (if a metal duct is replaced with an insulating material, for example). Consequently, unless you are sure that there is no de facto earth electrode, you must open the earth bar for any earth resistance measurements. To detect any de facto earth electrodes, it may be useful to measure the earth electrodes with the bar open and with the bar closed so that you can check whether the "closed-bar" value is due to the...

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Earth/ground measurement guide ›› Phase-PE loop measurement Earth resistance measurements on networks with multiple earthing systems in parallel (only on TT systems) In urban environments, it is often difficult to measure earth resistances with methods using stakes because it is impossible to set up the stakes for reasons of space, concreted areas, etc. For this reason, the standards for electrical installation testing allow measurements by the loop impedance method if it proves impossible to use stakes. Cf IEC 60364-6: "NOTE: if it is not possible to measure RA, this measurement can be...

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Earth/ground resistance an soil resistivity testers Due to the use of auxiliary stakes and more particularly the 0 V reference with the S stake, this method ensures accurate measurement of the earth resistance. Voltage generator ›› Earth loop measurement with 2 clamps and measurement with an earth clamp Measuring without disconnecting the earth bar and without earth stakes To correctly identify the measurement current and avoid disturbance currents, the earth clamp uses a specific measurement frequency. For example, take the case of a parallel earth network in which we want to measure the...

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