MIL-DTL-13777K
4.8.1.1 Physical tests. In order to determine the compliance of the copper conductor strands with the
characteristics specified in 3.5.1.1, the elongation shall be measured by method 3211 of FED-STD-228. Five
percent of the strands but not less than seven strands taken away from any one conductor of the sample shall
be so tested. Tensile strength of steel strands shall be in accordance with 3.5.1.2.
4.8.1.1.1 Retests. If the results of physical tests on one conductor are found to be below the specified value
for elongation, two more conductors shall be taken from the sample and 1% of the strands but not less than 10
strands taken form each of these conductors shall be tested. The average of all the strands tested shall
determine acceptance or rejection of the lot.
4.8.1.2 Coating tests. Tinned strands shall be tested for continuity and adhesion of coating in accordance with
4.8.1.3 Conductor resistance. The individual conductors shall be tested in accordance with method 6021 of
FED-STD-228, except that the dc bridge measurements shall be made with an accuracy of 0.5% (see 3.5.1.4).
To ascertain added length of conductor due to cabling, conductors shall be removed from a 5-foot length of
cable, their straightened length shall be measured, and the ratio of straightened length of conductor to original
length of cable shall be computed.
4.8.2 Insulation compound. Insulating compound shall be tested in accordance with the following physical and
4.8.2.1 Physical tests. These tests shall be made not sooner than 48 hours after vulcanization of the cable
sheath. The method of conducting these tests shall be as outlined in the succeeding paragraphs. In all cases,
the test temperature shall be between 68º to 83ºF.
4.8.2.1.1 Ultimate elongation. Ultimate elongation tests shall be made in accordance with method 3031 of
4.8.2.1.2 Tensile strength. Tensile strength tests shall be made using a straight specimen in accordance with
method 3021 of FED-STD-228.
4.8.2.2 Accelerated aging tests. Specimens shall be oven aged at a temperature of 208º to 212ºF for 48
hours.
4.8.2.2.1 Depreciation in elongation and tensile strength. After aging, the specimens shall be tested in
4.8.2.2.2 Shrinkage. An 8 inch (203.20 mm) specimen shall be cut from the insulated conductor. The
polyamide jacket shall be removed. The specimen shall then be cut to 6 inches (152.40 mm) with the
conductor flush with the insulation. The specimen shall be heated in a forced convection air oven at 210º± 2ºF
for a period of 24 hours. The specimen shall be removed and allowed to return to room temperature. The
amount the conductor extends beyond the insulation shrinkage shall be in accordance with 3.5.
4.8.2.3 Heat stability test (polyamide jackets).
4.8.2.3.1 Polyamide jackets over primary insulation. A one foot specimen shall be bent around a metal
mandrel six times the outside diameter of the specimen for tow turns and taped down on its ends. The
specimen and the mandrel shall be placed in a gravity convection type oven at a temperature of 200ºF±5ºF for
a period of 24 hours. Remove specimen and mandrel from oven and cool in a silica gel desiccator or equivalent
until it returns to room temperature (1 hour minimum). Remove from desiccator and straighten the specimen.
The specimen shall be visually inspected for tears and cracks. Wrinkles shall not be cause for rejection.
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