Soil Resistivity and Grounding System Resistivity...Key Variable in System Design ... – IEEE Standard 142 1100 Equipment Dependent ... – The ground system is part of a parallel network

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<ul><li><p>Soil Resistivityandand</p><p>Grounding System TestingGrounding System Testing</p><p>Roy Chip WhittenSenior Applications Engineer/Education SpecialistLyncole Grounding Solutions, LLC </p></li><li><p>What Is Grounding ?What Is Grounding ?</p><p>A l t i l ti h th i t ti l id t l b tAn electrical connection, whether intentional or accidental between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earthbody that serves in place of the earth. </p></li><li><p>Reasons For GroundingReasons For Grounding</p><p>Personnel safety and equipment protection by providing aPersonnel safety and equipment protection by providing apath to safely dissipate any unwanted charges or potentials.</p><p>Ensure equipment performance and protection Ensure equipment performance and protection</p><p> Satisfy manufacturers warrantySatisfy manufacturer s warranty</p></li><li><p>Electrical Protection PyramidElectrical Protection Pyramid</p><p>RFRFAC SurgeAC Surge</p><p>Telco / DataTelco / DataLightningLightning</p><p>GroundingGroundingGroundingGrounding</p></li><li><p>Resistance To EarthResistance To Earth</p><p>25 Ohms</p><p>20v 12v 10.6v11v16v 10.18v10.5v 10.45v 0</p></li><li><p>SoilR i ti itResistivity</p><p>BasicsBasics</p></li><li><p>Soil Resistivity</p><p>Key Variable in System Design</p><p> Determines grounding system resistance Changes from Site to Site Dependent on:</p><p> Soil type Moisture Electrolytes Temperature</p></li><li><p>Soil Resistivity Comparison</p><p>SurfaceSurface SoilsSoils 100100 -- 5,0005,000Soil TypeSoil Type Resistivity (ohmResistivity (ohm--cm)cm)</p><p>SurfaceSurface SoilsSoils 100 100 5,0005,000ClayClay 200 200 -- 10,00010,000Sand and GravelSand and Gravel 5,000 5,000 -- 100,000100,000Surface LimestoneSurface Limestone 10,00010,000 -- 1,000,0001,000,000Surface LimestoneSurface Limestone 10,000 10,000 1,000,0001,000,000LimestoneLimestone 500 500 -- 400,000400,000ShaleShale 500 500 -- 10,00010,000SandstoneSandstone 2,000 2,000 -- 200,000200,000,, ,,Granites,Granites, Basalts, etcBasalts, etc 100,000100,000Decomposed Decomposed GneissesGneisses 5,000 5,000 -- 50,00050,000Slates, etcSlates, etc 1,000 1,000 -- 10,00010,000,, ,, ,,</p></li><li><p>SoilR i ti itResistivity</p><p>TestingTesting</p></li><li><p>Soil Resistivity Testing</p><p> Key Variable in System Design 4 Point Wenner Method</p><p> Most Accurate Multiple Depth Testing</p></li><li><p>4-Pt. Wenner Method</p><p>Visually Survey Lease Area to Determine Location Visually Survey Lease Area to Determine Location and Direction For Test</p><p>Not parallel to buried metallic objects Not parallel to buried metallic objects Not parallel overhead power lines</p><p>Sufficient straight line distance to allow for test Sufficient straight line distance to allow for test</p><p> Minimal distance 300 feet</p></li><li><p>4-Pt. Wenner Method</p><p>C1P1P1P2P2C2C2</p><p>15 ft15 ft 10 ft10 ft 5 ft5 ft 0 ft0 ft15 ft15 ft 10 ft10 ft 5 ft5 ft 0 ft0 ft</p><p>AA</p></li><li><p>4-Pt. Wenner Method</p><p>Site AreaSite Area</p><p>Direction of TestDirection of Test</p></li><li><p>44--Pt. Wenner MethodPt. Wenner Method</p><p>Probe SpacingProbe Spacing Meter ReadingMeter Reading Calculated ResistivityCalculated Resistivity(Feet)(Feet) (Ohms)(Ohms) (Ohm(Ohm Meter)Meter)</p><p>= = 1.915 1.915 ARAR</p><p>(Feet)(Feet) (Ohms)(Ohms) (Ohm(Ohm--Meter)Meter)5 52.00 497.90</p><p>10 19.68 370.87</p><p>15 10.16 292.00</p><p>20 6.53 250.10</p><p>30 4 30 247 0430 4.30 247.04</p><p>40 10.80 827.28</p><p>60 7.40 850.26</p><p>80 5.58 855.60</p><p>100 4.44 850.26</p></li><li><p>T i lTypical Grounding Electrode SystemGrounding Electrode System</p><p>Resistance Requirementsq</p></li><li><p>Typical Resistance Requirements</p><p> NFPA 70 NEC 25 OHMS or Two Rods</p><p> IEEE Standard 142 &amp; 1100 Equipment Dependent</p><p> Motorola Standard R-56 10 OHMS (Design Goal)</p><p> Telecommunications 5 to 10 OHMS</p><p> Emerson DeltaV 3 OHMS</p><p> Essilor 3 OHMS</p><p> GE Medical Systems 2 OHMS</p></li><li><p>25 Ohm Grounding System</p><p>Lightning</p><p>StrikeStrike</p><p>18,000APotential Rise will be</p><p>~450KV at the site</p></li><li><p>5 Ohm Grounding System</p><p>Lightning</p><p>StrikeStrike</p><p>18,000APotential Rise will be</p><p>~90KV at the site</p></li><li><p>Grounding System Resistance Testing</p></li><li><p>Grounding System Testing</p><p> Why Test Grounds?y Determine Baseline </p><p>Validate Construction Confirm Design Spec </p><p>Satisfied</p><p> Validate Construction</p><p> Satisfy Warranty Reqs Ensure Equip Protection &amp; Performance</p></li><li><p>Testing Methods</p><p> Two Test Methods</p><p> Fall of Potential (Three Point) TestFall of Potential (Three Point) Test Clamp-on Test </p></li><li><p>Fall-of-Potential Method</p><p>RemoteRemoteCurrentCurrent</p><p>ElectrodeElectrodeC1C1P1P1</p><p>P2P2 Auxiliary Voltage ElectrodeAuxiliary Voltage ElectrodeGround Ground RodRod</p><p>EarthEarth</p><p>C2C2P1P1</p><p>11 ftft 110%0%220%0% 330%0% 440%0% 550%0%660%0%770%0%880%0% 990%0%RodRodUnder Under </p><p>TestTest</p><p>11 ftft 110%0%220%0% 330%0% 440%0% 550%0%660%0%770%0%880%0% 990%0%</p><p>1010 x depth of electrodex depth of electrode</p></li><li><p>Fall of Potential</p><p> Why 10+ Samples? Single Point Could Be Misinterpreted Data Must Be Plotted</p><p> Visual Plateau Confirms Test Validity</p><p>ohm</p><p>s)</p><p>125135145</p><p>y</p><p>ista</p><p>nce </p><p>(o</p><p>758595</p><p>105115125</p><p>Res</p><p>556575</p><p>0 10 20 30 40 50 60 70 80 90 100 P2 Probe Spacing</p></li><li><p>Fall Of Potential Test</p><p>Why Invalid? #1 Reason</p><p>l d</p><p>Why Invalid?</p><p> Not Isolating System Under Test Meter is a constant amperage meter Part of the current travels through the connection The ground system is part of a parallel network</p><p> Test Is Invalid Unless Disconnected</p></li><li><p>Fall Of Potential Test</p><p>Why Invalid?Why Invalid?</p><p> #2 Reason Insufficient Probe Spacing</p><p> Reqd to Avoid the Spheres of Influenceq p</p></li><li><p>Fall of Potential Test</p><p>S i C b ? Spacing For Current Probe? Single ElectrodeS g e ect ode</p><p> Minimum 5X Length of Rod Ideal, 10X Length of Rod</p><p> 10 Foot Rod, 50-100 Feet Away , y 200 Foot Well, 1000-2000 Feet Away</p></li><li><p>Ground Resistance Testing</p><p>Clamp-on Resistance Testing Clamp on Ground Resistance MeterClamp-on Ground Resistance Meter Convenient, Quick, Easy</p><p>i i i Does Not Require Disconnecting Equipment</p><p> Measures Current on the Ground</p><p>May Read Ground Loops vs. Ground ResistanceMay Read Ground Loops vs. Ground Resistancey py p</p></li><li><p>Clamp -on Meter Operation</p><p>2 Control Xformers</p><p>Current Flow</p><p>R = E / I</p><p>Current Flow??? ohms</p></li><li><p>ClampClamp--On Resistance Testing ExampleOn Resistance Testing Example3 Phase Utility 3 Phase Utility LineLine</p><p>Service MeterService Meter</p><p>Induced Current FlowInduced Current FlowInduced Current FlowInduced Current Flow</p><p>Ground ConductorGround Conductor</p><p>Ground RodsGround RodsCurrent From Other GroundsCurrent From Other Grounds C t F Oth G dC t F Oth G dGround RodsGround RodsCurrent From Other GroundsCurrent From Other Grounds Current From Other GroundsCurrent From Other Grounds</p></li><li><p>Invalid Clamp-on Reading</p><p>Reading: &lt; 1 Ohm</p><p>Current Path</p><p>gInvalid</p></li><li><p>THANK YOU FOR YOUR ATTENTION Please enjoy the rest of your time at thePlease enjoy the rest of your time at the</p><p>2013 BICSI Fall Conference &amp; ExhibitionRoy Chip Whitten</p><p>Senior Applications Engineer/Education Specialistpp g / pLyncole Grounding Solutions, LLC</p><p>800-962-2610 </p></li></ul>

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