ASTM D470-21

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D470 − 21
Standard Test Methods for
Crosslinked Insulations and Jackets for Wire and Cable
This standard is issued under the fixed designation D470; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 These test methods cover procedures for testing cross-
mine the applicability of regulatory limitations prior to use.
linked insulations and jackets for wire and cable.To determine
For specific hazards see Section 4.
the test to be made on the particular insulation or jacket, refer
1.6 This international standard was developed in accor-
totheproductspecificationforthattype.Thesetestmethodsdo
dance with internationally recognized principles on standard-
not apply to the class of products known as flexible cords.
ization established in the Decision on Principles for the
1.2 In many instances the insulation or jacket cannot be
Development of International Standards, Guides and Recom-
tested unless it has been formed around a conductor or cable.
mendations issued by the World Trade Organization Technical
Therefore, tests are done on insulated or jacketed wire or cable
Barriers to Trade (TBT) Committee.
in these test methods solely to determine the relevant property
of the insulation or jacket and not to test the conductor or
2. Referenced Documents
completed cable.
2.1 ASTM Standards:
1.3 These test methods appear in the following sections:
D149Test Method for Dielectric Breakdown Voltage and
Test Method Section(s)
DielectricStrengthofSolidElectricalInsulatingMaterials
at Commercial Power Frequencies
AC and DC Voltage Withstand Tests 22 to 29
Capacitance and Dissipation Factor Tests 38 to 44 D150Test Methods forAC Loss Characteristics and Permit-
Cold Bend 124
tivity (Dielectric Constant) of Solid Electrical Insulation
Cold Bend, Long-time Voltage Test on Short Specimens 51 to 57
D257Test Methods for DC Resistance or Conductance of
Double AC Voltage Test on Short Specimens 45 to 50
Electrical Tests of Insulation 17 to 64 Insulating Materials
Heat Distortion Test 123
D412TestMethodsforVulcanizedRubberandThermoplas-
Horizontal Flame Test 100
tic Elastomers—Tension
(Test Method
D7936)
D454TestMethodforRubberDeteriorationbyHeatandAir
Insulation Resistance Tests on Completed Cable 30 to 37
Pressure
Mineral Filler Content, Determination of 107 to 111
D572Test Method for Rubber—Deterioration by Heat and
Ozone Resistance Test 87 to 99
Partial-Discharge Test 58 to 64
Oxygen
Physical Tests of Insulation and Jacket Compounds 5 to 16
D573Test Method for Rubber—Deterioration in an Air
Surface Resistivity Test 112 to 116
Oven
Track Resistance Test 125 to 128
U-Bend Discharge Test 117 to 121 D1193Specification for Reagent Water
Water Absorption Test 65 to 71
D1711Terminology Relating to Electrical Insulation
Water Absorption Test, Accelerated 72 to 86
D2132Test Method for Dust-and-Fog Tracking and Erosion
Water Absorption Test on Fibrous Coverings 101 to 106
Resistance of Electrical Insulating Materials
1.4 Whenever two sets of values are presented, in different
D3755Test Method for Dielectric Breakdown Voltage and
units, the values in the first set are the standard, while those in
DielectricStrengthofSolidElectricalInsulatingMaterials
the parentheses are for information only.
Under Direct-Voltage Stress
1.5 This standard does not purport to address all of the
D5423Specification for Forced-Convection Laboratory Ov-
safety concerns, if any, associated with its use. It is the
ens for Evaluation of Electrical Insulation
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
Subcommittee D09.07 on Electrical Insulating Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 15, 2021. Published February 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1937. Last previous edition approved in 2013 as D470–13. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D0470-21. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D470 − 21
D7936Test Method for Flammability of Electrical Insulat- chambers, and test specimens so as to minimize the possibility
ingMaterialsIntendedforWiresorCablesWhenBurning ofsuchoccurrencesandtoeliminatethepossibilityofpersonal
in Horizontal Configuration injury. If the potential for fire exists, have fire suppression
2.2 ICEA Standard: equipment available. Design test equipment, test chambers,
and test specimens so as to minimize the possibility of such
T-24-380Guide for Partial-Discharge Procedure
occurrences and to eliminate the possibility of personal injury.
3. Terminology
See Sections 20, 27, 33, 42, 48, 54, 62, 68, 76, 114, 119 and
126.
3.1 Definitions:
3.1.1 For definitions of terms used in these test methods,
4.3 Ozone:
refer to Terminology D1711.
4.3.1 Ozone is a physiologically hazardous gas at elevated
3.2 Definitions of Terms Specific to This Standard:
concentrations. The exposure limits are set by governmental
3.2.1 aging (act of), n—exposure of material to air or oil at
agencies and are usually based upon recommendations made
a temperature and time as specified in the relevant material
by the American Conference of Governmental Industrial Hy-
specification for that material.
gienists. Ozone is likely to be present whenever voltages exist
which are suffıcient to cause partial, or complete, discharges in
3.3 Symbols:
air or other atmospheres that contain oxygen. Ozone has a
3.3.1 kcmil—thousands of circular mils.
distinctive odor which is initially discernible at low concen-
4. Hazards
trations but sustained inhalation of ozone can cause temporary
loss of sensitivity to the scent of ozone. Because of this it is
4.1 Mercury:
important to measure the concentration of ozone in the
4.1.1 (Warning—Mercury metal vapor poisoning has long
atmosphere, using commercially available monitoring devices,
been recognized as a hazard in industry. The maximum
whenever the odor of ozone is persistently present or when
exposure limits are set by the American Conference of Gov-
ozone generating conditions continue. Use appropriate means,
ernmental Industrial Hygienist. The concentration of mercury
such as exhaust vents, to reduce ozone concentrations to
vapor over spills from broken thermometers, barometers, and
acceptable levels in working areas. See Section 90.
other instruments using mercury can easily exceed these
exposure limits. Mercury, being a liquid with high surface
PHYSICAL TESTS OF INSULATIONS AND
tension and quite heavy, will disperse into small droplets and
JACKETS
seep into cracks and crevices in the floor. This increased area
of exposure adds significantly to the mercury vapor concen-
5. Significance and Use
tration in air. The use of a commercially available emergency
5.1 Physical tests, properly interpreted, provide information
spill kit is recommended whenever a spill occurs. Mercury
with regard to the physical properties of the insulation or
vapor concentration is easily monitored using commercially
jacket. The physical test values give an approximation of how
available sniffers. Make spot checks periodically around op-
the insulation will physically perform in its service life.
erations where mercury is exposed to the atmosphere. Make
Physical tests provide useful data for research and
thorough checks after spills. See 8.3.2 and 8.3.3.)
development, engineering design, quality control, and accep-
4.2 High Voltage:
tance or rejection under specifications.
4.2.1 Lethal voltages are a potential hazard during the
performance of this test method. It is essential that the test
6. Physical Tests
apparatus, and all associated equipment electrically connected
6.1 Physical tests shall include determination of the follow-
to it, be properly designed and installed for safe operation.
ing:
4.2.2 Solidly ground all electrically conductive parts
6.1.1 Tensile strength,
which it is possible for a person to contact during the test.
6.1.2 Tensile stress,
4.2.3 Provide means for use at the completion of any test to
6.1.3 Ultimate elongation,
ground any parts which were at high voltage during the test or
6.1.4 Permanent set,
have the potential for acquiring an induced charge during the
6.1.5 Accelerated aging,
test or retaining a charge even after disconnection of the
6.1.6 Tear resistance,
voltage source.
6.1.7 Effects of oil immersion, and
4.2.4 Thoroughly instruct all operators as to the correct
6.1.8 Thickness of insulations and jackets.
procedures for performing tests safely.
4.2.5 When making high voltage tests, particularly in com-
7. Sampling
pressed gas or in oil, it is possible for the energy released at
7.1 Number of Samples—Unless otherwise required by the
breakdown to be sufficient to result in fire, explosion, or
detailed product specification, wire and cable shall be sampled
rupture of the test chamber. Design test equipment, test
for the physical tests, other than the tests for insulation and
jacket thickness, as follows:
Available from The Insulated Cable Engineers Association, Inc. (ICEA), P.O. 2
7.1.1 Sizes Less than 250 kcmil (127 mm )—One sample
Box 2694, Alpharetta, GA 30023, http://www.icea.net.
shall be selected for each quantity ordered between 2000 and
Available from American Conference of Governmental Industrial Hygienists
(ACGIH),1330KemperMeadowDr.,Cincinnati,OH45240,http://www.acgih.org. 50000 ft (600 and 15000 m) of wire or cable and one
D470 − 21
additional sample for each additional 50000 ft. No sample imperfections. (Warning—See 4.1). Introduce the mercury at
shall be selected from lots of less than 2000 ft. one end of the specimen between the insulation and the tinned
7.1.2 Sizes of 250 kcmil (127 mm ) and Over—One sample surface of the conductor, with the specimen inclined on a
shall be selected for each quantity ordered between 1000 and supportwiththeendtowhichthemercuryisappliedatthetop.
25000ft(300and7600m)ofwireorcableandoneadditional The separation of the insulation results from the amalgamation
sample for each additional 25000 ft. No sample shall be ofthetinoftheconductorwiththemercury.Theamalgamation
selected from lots of less than 1000 ft. is assisted by first immersing and rubbing the tinning on the
exposedendoftheconductorinthemercury.Itisalsopossible
7.2 Size of Samples—Samples shall be at least 6 ft (2 m) in
2 to facilitate the removal of the insulation by stretching the
length when the wire size is less than 250 kcmil (127 mm ),
conductor to the breaking point in a tensile-strength machine.
andatleast3ft(1m)inlengthwhenthewiresizeis250kcmil
8.3.3 (Warning—Mercury is a hazardous material. See 4.1.
or over.
Care should be exercised to keep mercury from the hands.The
use of rubber gloves is recommended for handling specimens
8. Test Specimens
as in 8.3.2.)
8.1 Number of Specimens—From each of the samples se-
8.4 Specimens of Thin-Jacketed Insulation—In the case of
lected in accordance with Section 7, test specimens shall be
wires or cables having a thin jacket crosslinked directly to the
prepared as follows:
insulation, it is usually necessary to prepare die-cut specimens
Number of Test
of the jacket and insulation. Make an effort to separate the
Specimens
jacket from the insulation by slitting the covering through to
For Determination of Initial Properties (Unaged):
Tensile strength, tensile stress, and ultimate elongation 3
the conductor and pulling the jacket and insulation apart by
Permanent set 3
pliers. (Immersing the sample in hot water for a few minutes
For Aging Tests:
just prior to pulling off the jacket often facilitates this proce-
Air pressure, heat, or oxygen pressure 3
Air oven 3
dure.) If the jacket cannot be removed, prepare specimens by
For Oil Immersion 3
buffing. Equip the buffing apparatus with a cylindrical table
Onespecimenofeachthreeshallbetestedandtheothertwo
arrangedsothatitcanbeadvancedverygradually.Removethe
specimensheldinreserve,exceptthatwhenonlyonesampleis
conductor from two short lengths of wire by slitting the
selected all three specimens shall be tested and the average of
covering. Stretch one length of covering into the clamps of the
the results reported. For the tear test, six individual specimens
buffing apparatus so that it lies flat, with the jacket toward the
as described in 8.5 shall be used.
wheel. The jacket is buffed off, with due care not to buff any
further than necessary, or overheat the material. Repeat the
8.2 Size of Specimens—Inthecaseofwireandcablesmaller
than AWG 6 (13.3 mm ) having an insulation thickness less process with the other length of covering, except that the
insulation is buffed off. Die-cut specimens shall be prepared
than 0.090 in. (2.29 mm), the test specimen shall be the entire
section of the insulation. When the full cross section is used, from the buffed pieces after they have been allowed to recover
for at least 30 min. Jackets with a thickness of less than
the specimens shall not be cut longitudinally. In the case of
0.030in. (0.76 mm) shall not be tested.
wire and cable ofAWG 6 and larger, or in the case of wire and
cable smaller than AWG 6 having an insulation thickness
8.5 Specimen for Tear Test—Cut the specimen with a sharp
greater than 0.090 in., specimens approximately square in
knife or die. After irregularities, corrugations, and reinforcing
section with a cross section not greater than 0.025 in.
cords or wires have been removed, the test specimen shall
(16mm ) shall be cut from the insulation. In extreme cases,
conform to the dimensions shown in Fig. 1. The thickness of
use of a segmental specimen is permitted.
the test specimen shall be not greater than 0.150in. (3.81mm)
8.2.1 The test specimens shall be approximately 6 in.
and not less than 0.040 in. (1.02 mm). Split the specimen
(150mm) in length. Specimens for tests on jackets shall be
longitudinally with a new razor blade to a point 0.150in. from
taken from the completed wire or cable and cut parallel to the
the wider end.
axis of the wire or cable. With the exception of the tear tests,
8.6 Condition and Age—In accordance with Section 7, take
the test specimen shall be either a segment or sector cut with a
samples of the insulated wire and cable for physical and
suitable sharp instrument or a shaped specimen cut out with a
accelerated aging tests after crosslinking. Perform tests be-
die and shall have a cross-sectional area not greater than
2 tween 24 h and 60 days after crosslinking unless agreed to by
0.025in. (16mm ) after irregularities, corrugations, and rein-
themanufacturer.Donotheat,immerseinwater,orsubjectthe
forcing cords or wires have been removed by buffing.
8.3 Preparation of Specimens:
8.3.1 The test specimen is to have no surface incisions and
be as free as possible from other imperfections. Remove
surface irregularities, such as corrugations due to stranding,
etc., so that the test specimen will be smooth and of uniform
thickness.
8.3.2 The removal of the insulation often is greatly accel-
erated by using mercury. In most cases a test specimen which
is an entire section is obtained, free from surface incisions and FIG. 1 Test Specimens for Tear Test
D470 − 21
specimens to any mechanical or chemical treatment not spe- 10.3 When the cross section of the slice is not a segment of
cifically prescribed in these methods, unless agreed upon by a circle, calculate the area from a direct measurement of the
the producer and the purchaser. Age specimens having cable volume or from the specific gravity and the weight of a known
tape applied prior to crosslinking with such tape removed. length of the specimen having a uniform cross-section.
10.4 When the conductor is large and the insulation thin,
9. Measurement of Thickness of Specimens
and a portion of a sector of a circle is used, calculate the area
9.1 Make the measurement of thickness for cables with
as thickness times the width. This applies either to a straight
unbondedcomponentswitheitheramicrometerormicroscope,
test specimen or to one stamped out with a die, and assumes
but, for cables with bonded components, use only a micro-
that corrugations have been removed.
scope. The micrometer and microscope shall be capable of
10.5 When the conductor is large and the insulation thick,
making measurements accurate to at least 0.001 in.
and a portion of a sector of a circle is used, calculate the area
(0.025mm).
as the proportional part of the area of the total cross section.
9.1.1 Micrometer Measurements—When a micrometer is
used,taketheaveragethicknessoftheinsulationasone-halfof
10.6 Determine the dimensions of aged specimens before
the difference between the mean of the maximum and mini-
beginning the aging cycle.
mumdiametersovertheinsulationatonepointandtheaverage
diameter over the conductor or any separator measured at the
11. Physical Test Procedures
same point. Take the minimum thickness of the insulation as
11.1 Determine the physical properties in accordance with
the difference between a measurement made over the conduc-
Test Methods D412, except as specified in the following:
tor or any separator plus the thinnest insulation wall, and the
diameter over the conductor or any separator. Make the first
11.2 Test the specimens at a temperature of 68 to 82 °F (20
measurement after slicing off the thicker side of the insulation.
to 28 °C).
Do not include the thickness of any separator in the thickness
11.3 For all physical tests, except the set test, mark the
of insulation.
specimens with gauge marks 1 in. (25 mm) apart and place in
9.1.1.1 If the wire or cable has a jacket, remove the jacket
the jaws of the testing machine with a maximum distance
and determine the minimum and maximum thickness of the
between the jaws of 4 in. (100 mm). For the set test mark the
jacket directly with a micrometer. Take the average of these
specimens with gauge marks 2 in. (50 mm) apart.
determinations as the average thickness of the jacket.
9.1.2 Microscope Measurements—When a microscope is 11.4 Set Test—Make a set test on a separate test specimen
used, determine the maximum and minimum thickness from a having a length of approximately 6 in. (150mm) and mark
specimen cut perpendicular to the axis of the sample so as to with gauge marks 2 in. (50 mm) apart. Place the specimen in
expose the full cross-section. Take the average of these the jaws of the testing machine with a maximum distance
determinations as the average thickness. betweenjawsof4in.(100mm)andstretchattherateof20in.
(500 mm)/min (jaw speed) until the gauge marks are 6 in.
9.2 Number of Thickness Measurements—When the lot of
(150mm) apart. Release the test specimen within 5 s, and
wire to be inspected consists of two coils or reels, or less, at
determine the distance between bench marks 1 min after the
leastonedeterminationofthethicknessismadeoneachcoilor
beginning of release. The set is the difference between this
reel. When the lot consists of more than two coils or reels and
length and the original 2-in. (50 mm) gauge length, expressed
less than 20 coils or reels, make at least one determination of
as a percentage.
the thickness on each of two coils or reels taken at random. If
the lot consists of 20 or more coils or reels, select more than
11.5 Tear Test—Make a tear test on a minimum of six
10% of the coils or reels at random and make at least one
individual test specimens prepared as described in 8.5. Place
determination of the thickness on each coil or reel so selected.
the two halves of the split end of the test specimen in the jaws
of the tension testing machine and separate the jaws at the rate
10. Calculation of Area of Specimens
of 20 in. (500 mm)/min. Determine the tear resistance by
10.1 When the total cross section of the insulation is used, dividing the load in pounds (or kilograms) required to tear the
take the area as the difference between the area of the circle section by the thickness of the test specimen in inches (or
whose diameter is the average outside diameter of the insula- millimeters).Considertheaverageoftheresultsobtainedonall
tion and the area of the conductor. Calculate the area of a test specimens as the value of the tear resistance.
stranded conductor from its maximum diameter.
12. Aging Test Procedures
10.2 When a slice cut from the insulation by a knife held
tangent to the wire is used, and the slice so cut has the cross
12.1 Age specimens in accordance withTest Method D454,
sectionofasegmentofacircle,calculatetheareaasthatofthe
D572,orD573,andSpecificationD5423,exceptasspecifiedin
segment of a circle whose diameter is that of the insulation.
12.2 and 12.3.
The height of the segment is the thickness of insulation on the
12.2 The test period and temperature of aging is as pre-
side from which the slice is taken. (If necessary, obtain the
scribed in the product specification.
valuesfromatablegivingtheareasofsegmentsofaunitcircle
for the ratio of the height of the segment to the diameter of the 12.3 Between 16 and 96 h after the completion of the aging
circle.) process, subject the aged specimens to tensile strength and
D470 − 21
ultimate elongation tests in accordance with Section 11. insulation will perform under conditions similar to those
Perform physical tests on both aged and unaged specimens at observed in the tests. Electrical tests provide useful data for
the same time. research and development, engineering design, quality control,
and acceptance or rejection under specifications.
13. Oil Immersion Test
18. Types of Voltage Tests
13.1 Oil Immersion Test for Oil-resistant Jackets—Immerse
buffed die-cut specimens in ASTM Oil No. 2, IRM 902, or
18.1 Performvoltagewithstandtestsusingeitheralternating
equivalent at 121 6 1 °C for 18 h. At the end of the 18 h
or direct current, or both, applied in accordance with Test
remove the specimens from the oil and allow to rest at room
Methods D149 and D3755, and as specified in the following
temperature for a period of 4 6 ⁄2 h. Determine the tensile
sections. Perform the partial discharge test in accordance with
strength and elongation at the same time that the original
ICEA T-24-380. The partial discharge, ac voltage, insulation
properties are determined (see Section 11).
resistance, and dc voltage tests are performed on entire lengths
of completed cable.
13.2 Calculations for Tensile Strength and Measurement of
Elongation—The calculations for tensile strength are based on
19. Order of Testing
the cross sectional area of the specimen obtained before
immersion in the oil. Likewise, the elongation is based on the 19.1 Perform the partial discharge, ac voltage, insulation
original distance between the gauge marks applied to the resistance, and dc voltage tests in that order when any of these
specimen before immersion in the oil. tests are required. The sequence of other testing is not
specified.
14. Retests
20. Hazards
14.1 Ifanyspecimenfailstoconformtothevaluesspecified
for any test, either before or after aging, repeat that test on two
20.1 (Warning—These tests involve the use of high volt-
additional specimens from the same sample, except that when
ages. See 4.2).
the value of tear resistance from the first set of six specimens
21. Sampling, Test Specimens, and Test Units
failstoconform,testtwoadditionalsets.Failureofeitherofthe
retests indicates nonconformity of the sample to the require-
21.1 The specimen is defined in each test method.
ment specified.
AC and DC VOLTAGE WITHSTAND TESTS
15. Report
22. Significance and Use
15.1 Report the following information:
15.1.1 Manufacturer’s name,
22.1 Voltage withstand tests are useful as an indication that
15.1.2 Manufacturer’s lot number, if applicable,
the cable can electrically withstand the intended rated voltage
15.1.3 Calculated values of thickness, tensile strength, ten-
with adequate margin. These tests are normally performed in
sile stress, ultimate elongation, set, and tear resistance,
thefactoryandareusedforproductacceptancetospecification
15.1.4 All observed and recorded data on which the calcu-
requirements.
lations are based,
15.1.5 Date of vulcanization of the rubber, if known, 23. Apparatus
15.1.6 Dates of all tests,
23.1 AC Apparatus—For ac tests, use a voltage source and
15.1.7 Ambient temperatures during the period of physical
a means of measuring the voltage that is in conformance with
testing,
the voltage source and voltage measurement sections of the
15.1.8 Type of testing machine used,
apparatus section of Test Method D149. Use a power supply
15.1.9 Method of aging, and
having a frequency of 49 to 61 Hz.
15.1.10 Time and temperature of aging.
23.2 DC Apparatus—For dc tests, use any source of dc, but
16. Precision and Bias if using rectified alternating current, limit the dc ripple to 4%.
Measure the voltage with an electrostatic voltmeter or, in the
16.1 Thistestmethodhasbeeninuseformanyyears,butno
case of the rectifying equipment, with suitable low-voltage
information has been presented to ASTM upon which to base
indicators, provided the latter are so connected that their
a statement of precision. No activity has been planned to
indications are independent of the test load. See Test Method
develop such information.
D3755.
16.2 Thistestmethodhasnobiasbecausethevaluesforthis
23.3 Grounded Water Tank—For tests requiring immersion
test is determined solely in terms of the test method itself.
in water, a metal water tank connected to ground or a tank of
other material containing a grounded metal plate or bar is
ELECTRICAL TESTS OF INSULATION
required.
17. Significance and Use
24. Sampling, Test Specimens, and Test Units
17.1 Electrical tests, properly interpreted, provide informa-
tion with regard to the electrical properties of the insulation. 24.1 The specimen consists of entire lengths of completed
The electrical test values give an indication as to how the cable.
D470 − 21
25. Rate of Voltage Application 27. Procedure
25.1 Increase the applied voltage (from zero unless other-
27.1 (Warning—These tests involve the use of high volt-
wise specified), at a uniform rate, from the initial value to the ages. See 4.2.)
specified full test voltage within 60 s.
27.2 Where the insulation on a single-conductor cable or on
individual conductors of a multiple-conductor cable is covered
26. Application of Voltage to Cable
with a crosslinked or thermoplastic jacket, either integral with,
26.1 Single conductor Cables without Shield, Sheath, or
or separate from, the insulation, or where the thickness of the
Armor:
insulation is increased for mechanical reasons, determine the
26.1.1 Apply the specified voltage between the conductor
test voltage by the size of the conductor and the rated voltage
and water while the cable is still immersed in the water and
of the cable and not by the apparent thickness of insulation.
after it has been immersed for at least 6 h.
27.3 AC Tests:
26.2 Fibrous covered Cables without Metallic Sheath, Me-
27.3.1 Test each insulated conductor for 5 min at the ac
tallic Shield, or Metallic Armor:
withstand voltage given in Table 1A, Table 1C, and Table 1D.
26.2.1 Test single-conductor cables of this type prior to the
This test method is not necessary for non-shielded conductors
application and saturation of the fibrous covering. Apply the
rated up to 5000Vif the dc voltage test described in 27.4 is to
specified voltage between the conductor and the water while
be performed.
the cable is still immersed in water and after it has been
27.3.2 Do not apply a starting ac voltage (initial voltage)
immersed for at least 6 h.
greater than the rated ac voltage of the cable under test.
26.2.2 Test multiple-conductor cables of this type after the
application and saturation of the fibrous covering and after
27.4 DC Tests:
assembly. Without immersing the cable in water (dry test),
27.4.1 Uponcompletionoftheinsulationresistancetest,test
apply the specified voltage between each conductor and all
eachinsulatedconductorratedforserviceat5001Vandabove
other conductors.
for15minatthedcwithstandvoltagegiveninTable1B,Table
1C, and Table 1D.
26.3 Jacketed Cables and Integral Insulation and Jacket
27.4.2 Uponcompletionoftheinsulationresistancetest,test
without Metallic Sheath, Metallic Shield, or Metallic Armor:
each non-shielded conductor rated up to 5000 V for 5 min at
26.3.1 When single-conductor cables of this type are
the dc withstand voltage given in Table 1B. Omit this test
twisted together into an assembly of two or more conductors
method for non-shielded conductors rated up to 5000 V if the
without an overall jacket or covering, apply the specified
ac voltage test described in 27.3 was performed.
voltage between each conductor and the water. Test such
27.4.3 Do not apply a starting dc test voltage (initial
assemblieswhiletheyarestillimmersedinwaterandafterthey
voltage)greaterthan3.0timestheratedacvoltageofthecable
have been immersed for at least 1 h.
undertest.Thetestvoltageispermittedtobeofeitherpolarity.
26.3.2 Test all other single-conductor cables of this type
after immersion in water for at least 6 h and while still
immersed. 28. Report
26.3.3 Testeachconductorofmultiple-conductorcablewith
28.1 Report the following information:
overall jacket against all other conductors connected to the
28.1.1 Manufacturer’s name,
grounded water tank.
28.1.2 Manufacturer’s lot number, if applicable,
26.4 Cables with Metallic Sheath, Metallic Shield, or Me-
28.1.3 Description of the cable construction,
tallic Armor:
28.1.4 Voltage and time of application,
26.4.1 Test all cables of this type with the sheaths, shields,
28.1.5 Whetherornotthecablewasimmersedinwater,and
or armors grounded, without immersion in water, at the
28.1.6 Whether or not the cable withstood the required
specified test voltage. For cables having a metallic sheath,
voltage for the specified time.
shield, or armor over the individual conductor(s), apply the
specifiedtestvoltagebetweentheconductor(s)andground.For
29. Precision and Bias
multiple-conductorcableswithnonshieldedindividualconduc-
29.1 No information is presented about the precision of this
tors having a metallic sheath, shield, or armor over the cable
test method because the test result is non-quantitative.
assembly, apply the specified test voltage between each con-
ductor and all other conductors and between each conductor 29.2 No information is presented about the bias of this test
and ground. method because the test result is non-quantitative.
D470 − 21
TABLE 1 A Conductor Sizes, Insulation Thicknesses, and AC Test Voltages for Rubber Insulations
NOTE 1—These tables are intended for test voltage purposes only. The conductor sizes and insulation thicknesses given in each voltage class are not
necessarily suitable for all types of cable or conditions of service where mechanical stresses govern.
NOTE 2—To limit the maximum voltage stress on the insulation at the conductor to a safe value, the minimum size of the conductor shall be in
accordancewithTable1A.Forcablesorconditionsofservicewheremechanicalstressesgovern,suchasinsubmarinecablesorlongverticalrisers,larger
conductor sizes are recommended.
NOTE 3—Where the insulated conductor or conductors are covered by rubber or thermoplastic jackets, either integral with the insulation or separate
therefrom, or where the thickness of the insulation is increased for nonsheathed submarine cables or for mechanical reasons, the test voltage shall be
determined by the size of the conductor and rated voltage of the cable and not by the apparent thickness of the insulation.
NOTE 4—The actual operating voltage shall not exceed the rated circuit voltage by more than 5% during continuous operation or 10% during
emergencies lasting not more than 15 min.
NOTE 5—The selection of the cable insulation level to be used in a particular installation shall be made on the basis of the applicable phase-to-phase
voltage and the general system category as outlined in the following paragraphs:
100 % Level—Cables in this category are recommended where the system is provided with relay protection such that ground faults will be cleared as
rapidly as possible, but in any case within 1 min. While these cables are applicable to the great majority of cable installations which are on grounded
systems, they are also used also on other systems for which the application of cables is acceptable provided the above clearing requirements are met in
completely de-energizing the faulted section.
In common with other electrical equipment, the use of cables is not recommended on systems where the ratio of the zero to positive phase reactance
of the system at the point of cable application lies between −1 and −40 since excessively high voltages are likely to be encountered in the case of ground
faults.
133 % Level—This insulation level corresponds to that formerly designated for ungrounded systems. Cables in this category are recommended in
situations where the clearing time requirements of the 100% level category cannot be met, and yet there is adequate assurance that the faulted section
will be de-energized in a time not exceeding 1 h. Also they are used when additional insulation strength over the 100% level category is desirable.
173 % Level—Cables in this category should be applied on systems where the time required to de-energize a grounded section is indefinite. Their use
is recommended also for resonant grounded systems. Consult the manufacturer for insulation thicknesses.
NOTE 6—Do not use single-conductor cables in sizes AWG 9 and smaller for direct earth burial.
NOTE 7—Where additional insulation thickness is desired, it shall be the same as for the 133% insulation level.
NOTE 8—These thicknesses are based on unipass construction. Where cable is provided with a protective covering, these insulation thicknesses shall
be 90 mils (2.29 mm) for all conductor sizes listed.
NOTE 9—For 133% insulation level (ungrounded neutral), the minimum conductor size is AWG 1.
Insulation Thickness AC Test Voltage, kV
100 % Insulation Level 133 % Insulation Level Other Than Ozone-Resisting
Ozone-Resisting Insulations
Rated Circuit (Grounded Neutral) (Ungrounded Neutral) Insulations
Conductor Size, AWG
Voltage, Phase-to-
100 % Insula- 133 % Insula- 100 % Insula- 133 % Insula-
or kcmil (mm )
Phase, V
tion Level tion Level tion Level tion Level
in. mm in. mm
(Grounded (Ungrounded (Grounded (Ungrounded
Neutral) Neutral Neutral) Neutral)
0 to 600 18 to 16 (0.823 to 1.31) 0.030 0.76 0.030 0.76 1.0 1.0 1.0 1.0
14 to 9 (2.08 to 6.63) 0.045 1.14 0.045 1.14 3.0 3.0 4.5 4.5
8 to 2 (8.37 to 33.6) 0.060 1.52 0.060 1.52 3.5 3.5 6.0 6.0
1 to 4/0 (42.4 to 107) 0.080 2.03 0.080 2.03 4.0 4.0 7.5 7.5
225 to 500 (114 to 253) 0.095 2.41 0.095 2.41 5.0 5.0 8.5 8.5
525 to 1000 (266 to 507) 0.110 2.79 0.110 2.79 6.0 6.0 10.0 10.0
1000 (over 507) 0.125 3.18 0.125 3.18 7.0 7.0 11.5 11.5
601 to 1000 14 to 8 (2.08 to 8.37) 0.060 1.52 0.060 1.52 5.0 5.0 6.0 6.0
7 to 2 (10.6 to 33.6) 0.080 2.03 0.080 2.03 6.0 6.0 7.5 7.5
1 to 4/0 (42.4 to 107) 0.095 2.41 0.095 2.41 7.5 7.5 8.5 8.5
225 to 500 (114 to 253) 0.110 2.79 0.110 2.79 9.0 9.0 10.0 10.0
525 to 1000 (266 to 507) 0.125 3.18 0.125 3.18 10.0 10.0 11.5 11.5
1000 (over 507) 0.140 3.56 0.140 3.56 11.5 11.5 11.5 11.5
1001 to 2000 14 to 8 (2.08 to 8.37) 0.080 2.03 0.080 2.03 6.0 6.0 7.5 7.5
7 to 2 (10.6 to 33.6) 0.095 2.41 0.095 2.41 7.5 7.5 8.5 8.5
1 to 4/0 (42.4 to 107) 0.110 2.79 0.110 2.79 9.0 9.0 10.0 10.0
225 to 500 (114 to 253) 0.125 3.18 0.125 3.18 10.0 10.0 11.5 11.5
500 (over 253) 0.140 3.56 0.140 3.56 11.5 11.5 11.5 11.5
2001 to 5000 8 to 4/0 (8.37 to 107) 0.155 3.94 0.155 3.94 . . 13.0 13.0
225 to 1000 (114 to 507) 0.170 4.32 0.170 4.32 . . 13.0 13.0
1000 (over 507) 0.190 4.83 0.190 4.83 . . 13.0 13.0
5001 to 8000 6 (13.6 and over) 0.190 4.83 0.250 6.35 . . . . . . 18 22
8001 to 15 000 2 (33.6 and over) 0.300 7.62 . . . . . . . . . . . . 27.0 . . .
1 (42.4 and over) . . . . . . 0.420 10.67 . . . . . . . . . 33
D470 − 21
TABLE 1 Continued
Insulation Thickness AC Test Voltage, kV
100 % Insulation Level 133 % Insulation Level Other Than Ozone-Resisting
Ozone-Resisting Insulations
Rated Circuit (Grounded Neutral) (Ungrounded Neutral) Insulations
Conductor Size, AWG
Voltage, Phase-to-
100 % Insula- 133 % Insula- 100 % Insula- 133 % Insula-
or kcmil (mm )
Phase, V
tion Level tion Level tion Level tion Level
in. mm in. mm
(Grounded (Ungrounded (Grounded (Ungrounded
Neutral) Neutral Neutral) Neutral)
15 001 to 25 000 1 (42.4 and over) 0.450 11.43 . . . . 38.0 . . .
25 001 to 28 000 1 (42.4 and over) 0.500 12.70 . . . . . . . . . . . . 42.0 . . .
TABLE 1 B Conductor Sizes, and DC Test Voltages for Rubber Insulations
DC Test Voltage, kV
Rated Circuit Voltage, Conductor Size, AWG or Other than Ozone-Resisting Insulations Ozone-Resisting Insulations
Phase-to-Phase, V kcmil (mm )
100 % Insulation Level 133 % Insulation Level 100 % Insulation Level 133 % Insulation Level
(Grounded Neutral) (Ungrounded Neutral) (Grounded Neutral) (Ungrounded Neutral)
0 to 600 18 to 16 (0.823 to 1.31) . . . .
14 to 9 (2.08 to 6.63) 9.0 9.0 13.5 13.5
8 to 2 (8.37 to 33.6) 10.5 10.5 18.0 18.0
1 to 4/0 (42.4 to 107) 12.0 12.0 22.5 22.5
225 to 500 (114 to 253) 15.0 15.0 25.5 25.5
525 to 1000 (266 to 507) 18.0 18.0 30.0 30.0
over 1000 (over 507) 21.0 21.0 34.5 34.5
601 to 1000 14 to 8 (2.08 to 8.37) 15.0 15.0 18.0 18.0
7 to 2 (10.6 to 33.6) 18.0 18.0 22.5 22.5
1 to 4/0 (42.4 to 107) 22.5 22.5 25.5 25.5
225 to 500 (114 to 253) 27.0 27.0 30.0 30.0
525 to 1000 (266 to 507) 30.0 30.0 34.5 34.5
over 1000 (over 507) 33.0 33.0 34.5 34.5
1001 to 2000 14 to 8 (2.08 to 8.37) 18.0 18.0 22.5 22.5
7 to 2 (10.6 to 33.6) 22.5 22.5 25.5 25.5
1 to 4/0 (42.4 to 107) 27.0 27.0 30.0 30.0
225 to 500 (114 to 253) 30.0 30.0 34.5 34.5
over 500 (over 253) 33.0 33.0 34.5 34.5
2001 to 5000 8 to 4/0 (8.37 to 107) . . 35.0 35.0
225 to 1000 (114 to 507) . . 35.0 35.0
over 1000 (over 507) . . 35.0 35.0
5001 to 8000 6 and over (13.6) . . 45.0 45.0
8001 to 15 000 2 and over (33.6) . . 70.0 .
1 and over (42.4) . . . 80.0
15 001 to 25 000 1 and over (42.4) . . 100.0 .
25 001 to 28 000 1 and over (42.4) . . 105.0 .
D470 − 21
TABLE 1 C Conductor Sizes, Insulation Thicknesses, and Test Voltages for Crosslinked Polyethylene Insulation
AC Test Voltage, kV for DC Test Voltage, kV for
Insulation Thickness for 100 and 133 % Insulation Levels 100 and 133 % Insulation 100 and 133 % Insulation
(Grounded and Ungrounded Neutral) Levels (Grounded and Levels (Grounded and
Rated Circuit Voltage, Phase-Conductor Size, AWG
2 Ungrounded Neutral) Ungrounded Neutral)
to-Phase, V or kcmil (mm )
Column A Column B
Column A Column B Column A Column B
in. mm in. mm
0 to 600 14 to 9 (2.08 to 6.63) 0.045 1.19 0.030 0.76 4.0 4.0 12.0 12.0
8 to 2 (8.37 to 33.6) 0.060 1.57 0.045 1.14 5.5 5.5 16.5 16.5
1 to 4/0 (42.4 to 107) 0.080 1.98 0.055 1.40 7.0 7.0 21.0 21.0
225 to 500 (114 to 253) 0.095 2.39 0.065 1.65 8.0 8.0 24.0 24.0
525 to 1000 (266 to 507) 0.110 2.77 0.080 2.03 10.0 10.0 30.0 30.0
601 to 2000 14 to 9 (2.08 to 6.63) 0.060 1.52 0.045 1.14 5.5 5.5 16.5 16.5
8 to 2 (8.37 to 33.6) 0.070 1.78 0.055 1.40 7.0 7.0 21.0 21.0
1 to 4/0 (42.4 to 107) 0.090 2.29 0.065 1.65 8.0 8.0 24.0 24.0
225 to 500 (114 to 253) 0.105 2.67 0.075 1.90 9.5 9.5 28.5 28.5
525 to 1000 (266 to 507) 0.120 3.05 0.090 2.29 11.5 11.5 34.5 34.5
100 % Insu- 133 % Insu- 100 % Insu- 133 % Insu-
100 % Insulation Level 133 % Insulation Level lation Level lation Level lation Level lation Level
(Grounded Neutral) (Ungrounded Neutral) (Grounded (Ungrounded (Grounded (Ungrounded
Neutral) Neutral) Neutral) Neutral)
Unshielded Unipass
2001 to 5000 8 to 4/0 (8.37 to 107) 0.110 2.79 0.110 2.79 13 13 35 35
225 to 500 (114 to 253) 0.120 3.05 0.120 3.05 13 13 35 35
525 to 1000 (266 to 507) 0.130 3.30 0.130 3.30 13 13 35 35
Shielded
2001 to 5000 8 to 1000 (8.37 to 507) 0.090 2.29 0.090 2.29 13 13 35 35
5001 to 8000 6 to 1000 (13.6 to 507) 0.115 2.92 0.140 3.56 18 22 45 45
8001 to 15 000 2 to 1000 (33.6 to 507) 0.175 4.45 0.215 5.46 27 33 70 80
15 001 to 25 000 1 to 1000 (42.4 to 507) 0.260 6.60 0.345 8.76 38 49 100 125
25 001 to 28 000 1 to 1000 (42.4 to 507) 0.280 7.11 . . 42 . 105 .
28 001 to 35 000 1/0 to 1000 (53.5 to 507) 0.345 8.76 . . 49 . 125 .
TABLE 1 D Conductor Sizes, Insulation Thicknesses, Test Voltages, and Corona Extinction Levels for Ethylene Rubber Insulation
Insulation Thickness AC Test Voltage DC Test Voltage
Rated Circuit Voltage,
Conductor Size,
100 % 133 % 100 % 133 %
100 % Insulation Level 133 % Insulation Level
Phase-to-Phase,
AWG or kcmil (mm )
Insulation Insulation Insulation Insulation
V
in. mm in. mm
Level, kV Level, kV Level, kV Level, kV
0 to 600 14 to 9 (2.08 to 6.63) 0.030 0.76 0.030 0.76 4.0 4.0 12.0 12.0
8 to 2 (8.37 to 33.6) 0.045 1.14 0.045 1.14 5.5 5.5 16.5 16.5
1 to 4/0 (42.4 to 107) 0.055 1.40 0.055 1.40 7.0 7.0 21.0 21.0
225 to 500 (114 to 253) 0.065 1.65 0.065 1.65 8.0 8.0 24.0 24.0
525 to 1000 (266 to 507) 0.080 2.03 0.080 2.03 10.0 10.0 30.0 30.0
601 to 2000 14 to 9 (2.08 to 6.63) 0.045 1.14 0.045 1.14 5.5 5.5 16.5 16.5
8 to 2 (8.37 to 33.6) 0.055 1.40 0.055 1.40 7.0 7.0 21.0 21.0
1 to 4/0 (42.4 to 107) 0.065 1.65 0.065 1.65 8.0 8.0 24.0 24.0
225 to 500 (114 to 253) 0.075 1.90 0.075 1.90 9.5 9.5 28.5 28.5
525 to 1000 (266 to 507) 0.090 2.29 0.090 2.29 11.5 11.5 34.5 34.5
2001 to 5000 8 to 1000 (8.37 to 507) 0.090 2.29 0.090 2.29 13 13 35 35
5001 to 8000 6 to 1000 (13.6 to 507) 0.115 2.92 0.140 3.56 18 22 45 45
8001 to 15 000 2 to 1000 (33.6 to 507) 0.175 4.45 . . 27 . 70 .
1 to 1000 (42.4 to 507) . . 0.215 5.46 . 33 . 80
15 001 to 25 000 1 to 1000 (42.4 to 507) 0.260 6.60 0.345 8.76 38 49 100 125
25 001 to 28 000 1 to 1000 (42.4 to 507) 0.280 7.11 . . 42 . 105 .
28 001 to 35 000 1 ⁄0 to 1000 (53.5 to 507) 0.345 8.76 . . 49 . 125 .
INSULATION RESISTANCE TESTS ON COMPLETED significant for short specimens or when atmospheric humidity
CABLE is high. It is usually desirable for a cable to have a high value
of insulation resistance. This test method is used for product
30. Significance and Use
acceptancetospecificationrequirements,butcanalsobeuseful
30.1 The insulation resistance of a cable is primarily a for quality control purposes in indicating consistency of
measurement of the volume resistance of the insulating manufacture. See Test Methods D257 for a more complete
material, although surface resistance across the ends can be discussion of the significance of insulation resistance tests.
D470 − 21
31. Apparatus 34.1.3 When the length of the cable tested differs from
1000ft (305 m), correct the measured value of insulation
31.1 Megohm Bridge—Use a megohm bridge or other
resistance to megohms-1000 ft by multiplying by the ratio
equipment described in Test Methods D257. Make the mea-
L/1000 (L/305) where L is the length in feet (metres).
surement at a voltage of 100 to 500 Vdc.
34.2 The insulation resistance of wire and cable varies
32. Sampling, Test Specimens, and Test Units
widely with temperature. If the temperature at the time
32.1 The specimen consists of entire lengths of completed
measurementwasmadediffersfrom60°F(15.6°C),adjustthe
cable.
resistancetothatat60°Fbymultiplyingthemeasuredvalueby
the proper correction factor from Table 2. Use the coefficient
33. Procedure
furnished by the manufacturer for the particular insulation or
33.1 (Warning—This test method involves the use of high
determine it in accordance with Section 35.
voltages. See 4.2.)
35. Determining Temperature C
...