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  • Soil Resistivity and GroundingSoil Resistivity and Grounding Systems Testing

    Roy Chip Whitten/Senior Applications Engineer/Education Specialist

    Lyncole Grounding Systems, LLCIn lieu of paper evaluations for each session at the Winter Conference, all evaluations may now be taken digitally from your laptop, tablet or smartphone.

    D l d h Wi C f A bi i /Download the Winter Conference App at www.bicsi.org/apps or go to www.bicsi.org/surveys to provide your feedback for each of the sessions you attend.

    For your safety please note that emergency exits are located to the left or right ofFor your safety, please note that emergency exits are located to the left or right of this room.

  • What Is Grounding?

    An 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 earth.

  • Reasons For GroundingReasons For Grounding

    P l f d i i b Personnel safety and equipment protection by providing a path to safely dissipate any unwanted charges or potentialscharges or potentials.

    Ensure equipment performance and protection

    Satisfy manufacturers warranty

  • Electrical Protection PyramidElectrical Protection Pyramid

    RFRFAC SurgeAC SurgeAC SurgeAC Surge

    Telco / DataTelco / Data

    LightningLightning

    GroundingGroundingGroundingGroundinggggg

  • Resistance To EarthResistance To Earth

    25 Ohms

    20v 12v 10.6v11v16v 10.18v10.5v 10.45v 0

  • SoilSoilResistivity

    Basics

  • Soil Resistivity

    Key Variable in System Design

    Determines grounding system resistance Changes from Site to Site Dependent on:

    Soil typeM i t Moisture

    Electrolytes Temperaturep

  • Soil Resistivity Comparison

    Soil Type Resistivity (ohm-cm)

    Surface Soils 100 - 5,000Clay 200 - 10,000Sand and Gravel 5,000 - 100,000Sand and Gravel 5,000 100,000Surface Limestone 10,000 - 1,000,000Limestone 500 - 400,000Sh l 500 10 000Shale 500 - 10,000Sandstone 2,000 - 200,000Granites, Basalts, etc 100,000Decomposed Gneisses 5,000 - 50,000Slates, etc 1,000 - 10,000

  • SoilSoilResistivity

    Testing

  • Soil Resistivity Testing

    Key Variable in System Design 4 Point Wenner Method

    Most Accurate Multiple Depth Testingp p g

  • 4-Pt. Wenner Method

    Visually Survey Lease Area to Determine Location and Direction For Test Not parallel to buried metallic objects Not parallel overhead power lines

    Sufficient straight line distance to allow for test Sufficient straight line distance to allow for test

    Minimal distance 300 feet

  • 4-Pt. Wenner Method

    C1P1P1P2P2C2C2 C1P1P1P2P2C2C2

    15 ft15 ft 10 ft10 ft 5 ft5 ft 0 ft0 ft

    AA

  • 4-Pt. Wenner Method

    Site Area

    Direction of Test

  • 4-Pt. Wenner Method

    Probe Spacing Meter Reading Calculated Resistivity(Feet) (Ohms) (Ohm-Meter)

    = 1.915 AR

    (Feet) (Ohms) (Ohm-Meter)

    5 52.00 497.90

    10 19 68 370 8710 19.68 370.87

    15 10.16 292.00

    20 6.53 250.10

    30 4.30 247.04

    40 10.80 827.28

    60 7.40 850.26

    80 5.58 855.60

    100 4.44 850.26

  • Typical ypGrounding Electrode System

    R i t R i tResistance Requirements

  • Typical Resistance Requirements

    NFPA 70 NEC 25 OHMS or Two Rods

    IEEE Standard 142 & 1100 Equipment Dependent

    Motorola Standard R-56 10 OHMS (Design Goal)

    Telecommunications 5 to 10 OHMS

    Emerson DeltaV 3 OHMS

    Essilor 3 OHMS

    GE Medical Systems 2 OHMS

  • 25 Ohm Grounding System

    Lightning

    StrikeStrike

    18,000A Potential Rise will be

    ~450KV at the site~450KV at the site

  • 5 Ohm Grounding System

    Lightning

    StrikeStrike

    18,000A Potential Rise will be

    ~90KV at the site~90KV at the site

  • Gro nding S stemGrounding System Resistance Testingg

  • Grounding System Testing

    Why Test Grounds?Why Test Grounds?

    Determine Baseline

    Confirm Design Spec Validate Construction

    Confirm Design Spec Satisfied

    Satisfy Warranty ReqsSatisfy Warranty Reqs Ensure Equip Protection & Performance

  • Testing Methods

    Two Test Methods

    Fall of Potential (Three Point) Test

    Clamp-on TestClamp on Test

  • Fall-of-Potential Method

    RemoteRemoteCurrentCurrentC1C1

    C2C2

    CurrentCurrentElectrodeElectrode

    C1C1P1P1

    P2P2 Auxiliary Voltage ElectrodeAuxiliary Voltage ElectrodeGround Ground RodRod

    UnderUnder

    EarthEarth11 ftft 110%0%220%0% 330%0% 440%0% 550%0%660%0%770%0%880%0% 990%0%

    Under Under TestTest 1010 x depth of electrodex depth of electrode

  • Fall of Potential

    Why 10+ Samples? Single Point Could Be MisinterpretedSingle Point Could Be Misinterpreted Data Must Be Plotted

    Visual Plateau Confirms Test Validity

    145

    y

    (ohm

    s)

    105115125135145

    Res

    ista

    nce

    65758595

    105

    R

    5565

    0 10 20 30 40 50 60 70 80 90 100 P2 Probe Spacing

  • Fall Of Potential Test

    #1 Reason

    Why Invalid?

    #1 Reason Not Isolating System Under Test

    Meter is a constant amperage meterp g Part of the current travels through the connection The ground system is part of a parallel network

    Test Is Invalid Unless Disconnected

  • Fall Of Potential Test

    Why Invalid?

    #2 Reason Insufficient Probe Spacing

    R d A id h S h f I fl Reqd to Avoid the Spheres of Influence

  • Fall of Potential Test

    Spacing For Current Probe? p g Single Electrode

    Minimum 5X Length of Rod Minimum 5X Length of Rod Ideal, 10X Length of Rod

    10 Foot Rod, 50-100 Feet Away 200 Foot Well, 1000-2000 Feet Away

  • Ground Resistance Testing

    Clamp-on Resistance Testing Cl G d R i t M tClamp-on Ground Resistance Meter Convenient, Quick, Easy

    Does Not Req ire Disconnecting Does Not Require Disconnecting Equipment

    Measures Current on the GroundMeasures Current on the Ground

    May Read Ground Loops vs. Ground ResistanceMay Read Ground Loops vs. Ground Resistance

  • Clamp-on Meter Operation

    2 Control Xformers

    Current Flow

    R = E / IR = E / I

    ??? ohms

    Current Flow

    ??? ohms

  • Clamp-On Resistance Testing Example

    3 Phase Utility 3 Phase Utility LineLine

    Service MeterService Meter

    Induced Current FlowInduced Current Flow

    Ground ConductorGround Conductor

    Ground RodsGround RodsCurrent From Other GroundsCurrent From Other Grounds Current From Other GroundsCurrent From Other Grounds

  • Invalid Clamp-on Reading

    Reading: < 1 Ohm

    InvalidCurrent Path

    Invalid

  • THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION Please enjoy the rest of your time at the

    2014 BICSI Winter ConferenceRoy Chip Whitten

    Senior Applications Engineer/Education SpecialistLyncole Grounding Solutions, LLC

    800-962-2610800 962 2610

  • Soil Resistivity and GroundingSoil Resistivity and Grounding Systems Testing

    Roy Chip Whitten/Senior Applications Engineer/Education Specialist

    Lyncole Grounding Systems, LLCIn lieu of paper evaluations for each session at the Winter Conference, all evaluations may now be taken digitally from your laptop, tablet or smartphone.

    D l d h Wi C f A bi i /Download the Winter Conference App at www.bicsi.org/apps or go to www.bicsi.org/surveys to provide your feedback for each of the sessions you attend.

    For your safety please note that emergency exits are located to the left or right ofFor your safety, please note that emergency exits are located to the left or right of this room.

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