MIL-DTL-55446D
4.4.1.3 Resistance. Measure the resistance of the conductors to verify that the resistance does not
exceed the 94Ω requirement at 20 °C.
4.4.1.4 Dielectric strength. Apply 1,500 V ac between each conductor in turn, and the remaining
conductors connected together, for one minute to verify that the insulation meets the dielectric
requirement. The conductors may be split into groups so that neither an adjacent single conductor nor
both conductors of a pair are in the same group.
4.4.1.5 Insulation resistance. Following the dielectric strength test of 4.4.1.4, verify the insulation
resistance between each conductor in turn and the remaining conductors connected together at 20 °C.
Use a testing voltage of not less than 100 V dc nor more than 550 V dc. The measured value shall meet
the requirement specified.
4.4.2 Physical inspections for insulation.
4.4.2.1 Tensile strength. A specimen of the insulation shall be tested in accordance with method
3021 of FED-STD-228.
4.4.2.2 Elongation. A specimen of the insulation shall be tested in accordance with method 3031 of
4.4.2.3 Adhesion. The insulation adhesion shall be verified by removing 4.5 inches (114 mm) of
insulation from one end and .25 inch (6.35 mm) from the other end of a 6-inch sample of insulated
conductor. The 4.5 inch (114 mm) end of the conductor shall be put through a .125-inch (3.17 mm) thick
brass plate having a hole approximately .010 inch (.254 mm) larger than the diameter of the wire. A loop
in the long end of the sample shall be made and a tension testing scale attached to this loop. The scale
shall be pulled at the rate of approximately 10 feet per minute to verify that the maximum pull required to
remove the conductor from the 1.25 inch (31.8 mm) of insulation is not over 3 pounds.
4.4.2.4 Shrinkage. Remove .5 inch (12.7 mm) of insulation from one end of a 6-inch (152 mm)
sample of insulated conductor taken from the finished cable. Immerse the bare conductor .25 inch
(6.35 mm) deep for 20 seconds into a pot of solder at approximately 160 °C. Examine the insulation to
verify that it has shrunk not more than .0625 inch (1.59 mm) from the end of the conductor.
4.4.2.5 Cold bend. Condition an 8 inch (203 mm) sample of an insulated conductor and a .0625 inch
(1.59 mm) diameter mandrel for one hour at -18±2 °C. At the end of the hour, while the sample and
mandrel are still in the cold box, wrap the sample for five consecutive turns in a closed helix about the
mandrel at the rate of approximately 60 turns per minute. Examine the insulation to verify that no cracks
are visible to the unaided eye.
4.4.2.6 Flammability. Suspend an 18 inch (457.20 mm) length of insulated conductor vertically in a
draft-free enclosure and apply the flame of a Bunsen burner for 5 seconds. The flame shall be applied so
that the apex of the blue cone is played on the lower portions of the wire at the angle of approximately
45 degrees. After removing the flame, the insulation shall be observed for self-extinguishment.
4.4.2.7 Compression strength. Condition a test specimen of insulated wire for at least 1 hour at a
temperature of 25±3 °C, at which temperature the compression strength shall be determined. Place the
test specimen between 2 inch x 2 inch (50.80 mm) x (50.80 mm) plates and measure the crushing load
required to cause contact between the wire and either of the plates when the approach speed of the
plates is approximately 2.25 inches (57.1 mm) per minute.
4.4.3 Physical inspections for jacket.
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