EARTHING/GROUNDING SYSTEMS, AN OVERVIEW EARTHING
Soilresistivitytesting
Commonimprovementstrategies:
The first stage of any earth system design is the undertaking of a
•Increaseelectrodesurfacearea
comprehensivesoilresistivitysurveytodeterminethemakeupofthesoiland
•Useacapacitiveenhancementproduct
aciditylevels.Fromthedataproducedasoilmodelwillbegeneratedtoassist •Increaseconductorsize
in determining the optimum location and depth of the electrode system. An
•Decreasethenumberofconnections
initial research phase is required to gather information about nearby metallic
structures,istheregeologicalsurveydataavailable?Ifsoobtainitanduseitas
•Lowerinductance
comparativedatawhenyoursoilsurveyisprocessedintoasoilmodel.Carry
•Increasecapacitance
outaCATscanoftheareaofthetesttoensuretherearenoelectricalcables
•Electrodesmustbespacedappropriatelyformaximumeffect.Theyshould
thatcandistortorbedamagedwhenthetestprobesaredrivenintotheground. ideally be equally spaced to their depth; for example a 10 meter deep rod
Prior to commencement of testing ensure the test instrument is set up shouldbe10metersawayfromthenextearthrod.
adequatelyi.e.powerlevels,frequency,interferenceandfiltering.Asearthing
systems are installed near the surface of the earth, the top soil layers being
subjecttohighercurrentdensitiesarethemostsignificantandrequirethemost
Groundimprovingproductsfor
accuratemodelling. Soilresistivity can vary significantly both with depth, and
earthingsystems
from one point to another at the site, and as such, a single soil resistivity
measurementisusuallynotsufficient.Takinganumberofmeasurementsalong
A number of products have been developed over the years to improve
alineusingdifferentspike separations,willprovideanindicationofhowthesoil
earthing arrangements. Some products have suffered with idiosyncratic
resistivity varies with depth, whilst taking measurements along different lines
problems,including:
willindicatehowtheresistivitychangesacrossthesiteoralternativelyifpossible •Substantial corrosion of copper elements; some materials available in the
ata90°tangent.
marketcancorrodemetalliccomponentsuntiltheyarecompletelydestroyed.
Aneffectiveearthsystemhasanumberofdefiningcharacteristics: •Unreliability and unpredictability of material behaviour after installation:
•Lowimpedanceground(lowresistance,lowinductance,highcapacitance) problems such as expansion post-installation resulting in distorted surface
•Abilitytodispersefullpotentialfaultcurrentlevels
levelprofile,causingtriphazardsandrequiringremedialaction.
•Abilitytowithstandrepeatedfaults •Easeofextractionandtheftofcopperearthing/groundingelements:theftof
•Highenergydissipationtorequisitelevels
valuablemetalliccomponentshasplaguedtheindustry.
•Properorientation •Environmentalpollution;Leechingawayofearthing/groundingimprovement
•Corrosionresistance
compound:thisproblemhasfacedanumberofproducts,whereduringand
•Theftresistant
subsequenttoinstallationithasleakedawayintofracturesinthesurrounding
•Lowtouchandsteppotentials
groundmass.
•Minimalbendsinconductorsystem(eliminate90°bendsifatallpossible) FMSudafixiscommittedtopossessingthebestproductrangeinthesector
•Maximisebendradiuswhereverbendsoccur and backfill earthing improvement materials are no exception. With the
•Earthpotentialriseiswithinacceptablelimits
evidenceprovidedbyindependenttestingitistheopinionofFMSudafixthat
•Transferpotentialsarewithinacceptablelimits
Conducrete® isthebestproducttosupportearthingprojects.Designedtoa
•Afunctionallifespanofapprox.30yearsprovidingthatthefacilityloador
demanding specification Conducrete® possesses impressive attributes to
structureisnotamended,whereuponaredesignofearthingsystemwill
enhanceearthingsystems.
benecessary. FormoreinformationonConducrete® pleaserefertotherelevantproductpage
a4 +44 (0)115 975 7600 www.fmsudafix.com 11
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