ASTM_G_165_-_99_2012.pdf

Designation:G16599(Reapproved 2012)Standard Practice forDetermining Rail-to-Earth Resistance1This standard is issued under the fixed designation G165;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the procedures necessary to followfor measuring resistance-to-earth of the running rails which areused as the conductors for returning the train operating currentto the substation in electric mass transit systems.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2G15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 cross bondinsulated copper cables that connectedbetween adjacent sections of track to ensure electrical conti-nuity between them.3.1.2 direct fixation fastenera device for fastening runningrails to their support structures.3.1.3 impedance bonda device connected to running railsfor automatic train operations.3.1.4 The terminology used herein,if not specifically de-fined otherwise,shall be in accordance with Terminology G15.Definitions provided herein,and not given in TerminologyG15,are limited to this practice.4.Significance and Use4.1 Low resistance between the rails and earth could resultin large magnitudes of stray earth currents with the attendantcorrosion damage to underground metallic structures.4.2 These measurements are of a low voltage type and arenot designed to evaluate the high voltage dielectric character-istics of the rail insulating elements.4.3 Sections of track with rail-to-earth resistances less thanacceptable minimums must be tested in greater detail todetermine the reason(s)for this condition.Determination of thereason(s)for any low rail-to-earth resistance may require theuse of special testing techniques or special instruments,orboth,beyond the scope of this practice.4.4 The electrical tests call for the use of electric meters thathave varying characteristics depending on cost,manufacture,and generic type.It is assumed that any person employing thetest procedures contained herein will know how to determineand apply proper correction factors and that they will havesufficient knowledge to ensure reasonable accuracy in the dataobtained.4.5 This practice does not encompass all possible fieldconditions to obtain rail-to-earth resistance characteristics.Nogeneral set of test procedures will be applicable to all situa-tions.5.Equipment5.1 Indicating dc;high impedance(minimum ten megohm)voltmeter(two required);multi-scale,capable of reading posi-tive and negative values without removing test leads;andcovering at least the following full scale ranges:5.1.1 0 to 10 mV,5.1.2 0 to 100 mV,5.1.3 0 to 1 V,5.1.4 0 to 10 V,and5.1.5 0 to 100 V.5.1.6 Meters shall be accurate within 1%of full scale.5.2 Direct current ammeter,multi-scale,covering the fol-lowing full scale ranges:5.2.1 0 to 1 A,1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.10 on Corrosion inSoils.Current edition approved May 1,2012.Published June 2012.Originallyapproved in 1999.Last previous edition approved in 2005 as G16599(2005).DOI:10.1520/G0165-99R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2.2 0 to 10 A,and5.2.3 0 to 100 A.5.3 Direct current milliammeter,multi-scale,covering thefollowing full scale ranges:5.3.1 0 to 15 mA,5.3.2 0 to 150 mA,and5.3.3 0 to 1500 mA,5.4 An alternative to the ammeter and milliammeter is amillivolt meter and external shunts covering the listed currentranges.Meters(and shunt combinations if used)shall beaccurate to within 1%of full scale.5.5 Direct current power source with control circuits.Generally,6 or 12 V automotive type wet cell batteries willsuffice.5.6 Test wires,assorted lengths and sizes,to suit fieldconditions.Wires should have minimum 600 V insulation inperfect condition(no visible cuts or abrasions)and be multi-strand copper conductors for flexibility.5.7 Miscellaneous