U\)This specification covers 2, 3, and 4 cadmium copper alloy stranded retractile conductor electrical cords. These cords are insulated with a natural rubber compound encased in a Buna S or Buna S and natural rubber compound jacket which is vulcanized in a helical spring coil form to produce a cord which will extend and retract freely. These cords are designed for use on communications equipment at audio frequencies, with a temperature range of -0 to 60 degrees C for continuous operation.

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MIL-DTL-13273C

surface. Frictional restraint shall be relieved by tapping on the surface. Force to extend its retracted

length within 5 seconds shall not exceed 20 pounds. The actual values shall be recorded and forwarded

with preproduction sample test data.

3.8.4 High temperature retraction.

3.8.4.1 High temperature retraction (+150�F � 2�F). While the coiled portion is extended to 3 times

its retracted length, the cords shall be conditioned by placing in an air oven maintained at a temperature

of 150�F � 2�F for 20 hours. While maintaining at this temperature, the coiled portion of the cord shall

then be capable of complying with the following: After the coiled portion is extended further to 5 times its

retracted length and returned to its original retracted length and stretched and returned in this manner for

a total of 3 times, the coiled portion shall not exceed 275% of its original retracted length when the cord is

held vertically for 15 seconds.

3.8.4.2 High temperature retraction (+185�F � 2�F). While the coiled portion is extended to 3 times

its retracted length, the cords shall be conditioned by placing in an air oven maintained at a temperature

of 185�F � 2�F for 20 hours. While maintaining at this temperature, the coiled portion of the cord shall

then be capable of complying with the following: After the coiled portion is extended further to 5 times its

retracted length and returned to its original retracted length and stretched and returned in this manner for

a total of 3 times, the coiled portion shall not exceed 275% of its original retracted length when the cord is

held vertically for 15 seconds.

3.8.5 Retraction after static loading. At room temperature, 30 minutes after being place on a flat

surface, the retracted length of the cord shall be not more than 110% of its original retracted length after

the coiled portion of the cord has been to extended to 250% of its original retracted length by the cord

being secured at one end and hung vertically with a weight attached to the lower end for 48 hours.

3.9 Electrical requirements.

3.9.1 DC resistance. The resistance of the stranded conductor shall not exceed 0.030 Ω per foot at

68�F.

3.9.2 Dielectric strength and insulation resistance. The electrical cord shall withstand without

dielectric breakdown, a potential of 500 volts dc (350 volts rms ac) for not less than 2 seconds, and shall

have an insulation resistance not less than 1000 megΩ with the potential applied between each conductor

and the remaining conductors connected together.

3.10 Preproduction test evaluation. The contractor shall submit 24 each retractile cords of each type

with test data, for preproduction test evaluation to determine compliance with the technical requirements

of this specification. Failure to meet the requirements of this specification will require corrective action

and resubmission of samples and test data.

3.11 Treatment of textiles. The cords shall be in accordance with MIL-DTL-3885, Treatment of

Textiles.

3.12 Workmanship. Cords shall be uniform in shape and free of kinks, splints, cuts, cracks,

abrasions, peeled surfaces, and any imperfections that can affect performance.