ASTM G165-99(2012)
(Practice)Standard Practice for Determining Rail-to-Earth Resistance
Standard Practice for Determining Rail-to-Earth Resistance
SIGNIFICANCE AND USE
Low resistance between the rails and earth could result in large magnitudes of stray earth currents with the attendant corrosion damage to underground metallic structures.
These measurements are of a low voltage type and are not designed to evaluate the high voltage dielectric characteristics of the rail insulating elements.
Sections of track with rail-to-earth resistances less than acceptable minimums must be tested in greater detail to determine the reason(s) for this condition. Determination of the reason(s) for any low rail-to-earth resistance may require the use of special testing techniques or special instruments, or both, beyond the scope of this practice.
The electrical tests call for the use of electric meters that have varying characteristics depending on cost, manufacture, and generic type. It is assumed that any person employing the test procedures contained herein will know how to determine and apply proper correction factors and that they will have sufficient knowledge to ensure reasonable accuracy in the data obtained.
This practice does not encompass all possible field conditions to obtain rail-to-earth resistance characteristics. No general set of test procedures will be applicable to all situations.
SCOPE
1.1 This practice covers the procedures necessary to follow for measuring resistance-to-earth of the running rails which are used as the conductors for returning the train operating current to the substation in electric mass transit systems.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G165 − 99 (Reapproved 2012)
Standard Practice for
Determining Rail-to-Earth Resistance
This standard is issued under the fixed designation G165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Definitions provided herein, and not given in Terminology
G15, are limited to this practice.
1.1 This practice covers the procedures necessary to follow
for measuring resistance-to-earth of the running rails which are
4. Significance and Use
used as the conductors for returning the train operating current
4.1 Low resistance between the rails and earth could result
to the substation in electric mass transit systems.
in large magnitudes of stray earth currents with the attendant
1.2 The values stated in SI units are to be regarded as the
corrosion damage to underground metallic structures.
standard. The values given in parentheses are for information
only. 4.2 These measurements are of a low voltage type and are
not designed to evaluate the high voltage dielectric character-
1.3 This standard does not purport to address all of the
istics of the rail insulating elements.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.3 Sections of track with rail-to-earth resistances less than
priate safety and health practices and determine the applica-
acceptable minimums must be tested in greater detail to
bility of regulatory limitations prior to use. determinethereason(s)forthiscondition.Determinationofthe
reason(s) for any low rail-to-earth resistance may require the
2. Referenced Documents
use of special testing techniques or special instruments, or
2 both, beyond the scope of this practice.
2.1 ASTM Standards:
G15 Terminology Relating to Corrosion and Corrosion Test-
4.4 The electrical tests call for the use of electric meters that
ing (Withdrawn 2010) have varying characteristics depending on cost, manufacture,
and generic type. It is assumed that any person employing the
3. Terminology test procedures contained herein will know how to determine
and apply proper correction factors and that they will have
3.1 Definitions of Terms Specific to This Standard:
sufficient knowledge to ensure reasonable accuracy in the data
3.1.1 cross bond—insulated copper cables that connected
obtained.
between adjacent sections of track to ensure electrical conti-
nuity between them.
4.5 This practice does not encompass all possible field
conditions to obtain rail-to-earth resistance characteristics. No
3.1.2 direct fixation fastener—adeviceforfasteningrunning
general set of test procedures will be applicable to all situa-
rails to their support structures.
tions.
3.1.3 impedance bond—a device connected to running rails
for automatic train operations.
5. Equipment
3.1.4 The terminology used herein, if not specifically de-
5.1 Indicating dc; high impedance (minimum ten megohm)
fined otherwise, shall be in accordance with Terminology G15.
voltmeter (two required); multi-scale, capable of reading posi-
tive and negative values without removing test leads; and
covering at least the following full scale ranges:
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion
5.1.1 0 to 10 mV,
of Metals and is the direct responsibility of Subcommittee G01.10 on Corrosion in
5.1.2 0 to 100 mV,
Soils.
5.1.3 0 to 1 V,
Current edition approved May 1, 2012. Published June 2012. Originally
approved in 1999. Last previous edition approved in 2005 as G165–99(2005). DOI:
5.1.4 0 to 10 V, and
10.1520/G0165-99R12.
5.1.5 0 to 100 V.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.1.6 Meters shall be accurate within 1 % of full scale.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
5.2 Direct current ammeter, multi-scale, covering the fol-
the ASTM website.
lowing full scale ranges:
The last approved version of this historical standard is referenced on
www.astm.org. 5.2.1 0 to 1 A,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G165 − 99 (2012)
5.2.2 0 to 10 A, and crossovers. The lengths of the track sections will vary within
5.2.3 0 to 100 A. the general range of 60 to 2750 m (200 to 9000 ft).
7.1.1 Remove cable connections from across rail insulators.
5.3 Direct current milliammeter, multi-scale, covering the
7.1.2 Disconnect cross bonds within section of track being
following full scale ranges:
tested and other track.
5.3.1 0 to 15 mA,
7.1.3 Disconnect power traction substation negative feeder
5.3.2 0 to 150 mA, and
cables from track section being tested.
5.3.3 0 to 1500 mA,
NOTE 1—Switches within substation can be opened.
5.4 An alternative to the ammeter and milliammeter is a
millivolt meter and external shunts covering the listed current 7.2 Ensure electrical continuity between the rails within the
ranges. Meters (and shunt combinations if used) shall be insulated track section being tested by the use of the existing
accurate to within 1 % of full scale. cables at impedance bonds or by installing temporary wire
connections between the rails.
5.5 Direct current power source with control circuits.
Generally, 6 or 12 V automotive type wet cell batteries will 7.3 Track-to-earthresistancemeasurementswillbeobtained
suffice.
as shown on Fig. 3 for main track sections and as shown on
Fig. 4 for main track sections containing double crossovers.
5.6 Test wires, assorted lengths and sizes, to suit field
Measurements on track sections containing turnouts and single
conditions. Wires should have minimum 600 V insulation in
crossovers will be similar to that shown on Fig. 4 with the
perfect condition (no visible cuts or abrasions) and be multi-
number of test points being determined by the electrical
strand copper conductors for flexibility.
configuration of insulating joints and bonding cables.
5.7 Miscellaneous tools as required for making wire
7.4 The track-to-earth resistance measurements for the track
connections, splicing, and so forth.
in the train storage yards will require special consideration for
5.8 Vehicle to transport equipment and personnel along
each section to be tested because of the number and location of
track to facilitate testing.
insulating joints resulting from the type of signal system being
used within the yard area and because of the number of cross
6. Visual Inspection
bonds and other bonding cables used within the yard.
6.1 The track section to be tested should be visually
7.5 All data shall be recorded.
examined to ensure the insulating components have been
7.6 A sketch showing location of the test and the electrical
installed and there is no debris, water, or other conductive
test set-up used shall be included.
material in electrical contact with the metallic track compo-
nents that could result in the lowering of the effective track-
7.7 The number of readings taken to determine an electrical
to-earth resistance thus producing incorrect data.
constant or property must be sufficient to ensure that random
factors due to human error in reading the instruments and
7. Electrical Tests
transient disturbances in the electrical network have negligible
7.1 Electricallyisolatesectionsoftrack(seetypicalarrange- influence on final results.Aminimum of three readings should
ments in Figs. 1 and 2). Length of track section to be tested is be obtained but additional readings may be required depending
dependent upon the locations of rail insulators. Rail insulators upon the exact circumstances of the test. The adequacy of data
are found at the ends of turnouts and single and double generally can be established by the tester. Once the specified
FIG. 1 Schematic Diagram — Typical Mainline Track Section
G165 − 99 (2012)
FIG. 2 Schematic Diagram — Typical Double Crossover Track Section
NOTE 1—All cable connections removed for measurements as shown on Fig. 1.
NOTE 2—Ground resistance to be on the order of 1/100 (or less) of the track-to-earth resistance for the section being tested.
FIG. 3 Schematic Diagram — Mainline Test Arrangement
minimum number of readings have been obtained, data should 7.8.5 Obtain similar data for:
be examined to see that removal of neither the highest nor the
delta E
R 5 (2)
lowest value will alter the arithmetic averag
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