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

4.4.7 Rejected lot. Failure of a lot to pass any test or inspection constitutes failure of the lot and the lot

shall be rejected. If an inspection lot is rejected, the contractor may rework the lot to correct the defects,

or screen out the defective units and resubmit the lot for re-inspection. Such lots shall be separated from

new lots and shall be identified as re-inspected lots.

4.4.8 Non-compliance. If a sample fails to pass any of the inspections, the contractor shall notify the

cognizant inspection activity of such failure and take corrective action on the materials or processes, or

both, as warranted, on all units of the product. Acceptance and shipment of the product shall be

discontinued until corrective action has been taken. After the corrective action has been taken, the

inspections shall be repeated on replacement articles. (This includes all tests and examinations, or only

the test that the original sample failed, at the option of the cognizant inspection activity.) Where group A

inspection is re-instituted, final acceptance and shipment shall be withheld until group B or C inspection

has shown that the corrective action was successful. In the event of failure after re-inspection,

information concerning the failure shall be provided to the cognizant inspection activity.

4.5 Methods of inspection.

4.5.1 Visual and mechanical inspection of finished wire on reels. The stranded wire shall be visually

inspected on reels for workmanship and miscellaneous defects before the insulating jacket is applied.

4.5.2 Tensile strength and elongation of strands. The tensile strength and elongation of strands shall

be tested in accordance with FED-STD-228, method 3211 to determine compliance with the requirements

of 3.1.

4.5.3 Visual and mechanical inspection of completed cord assembly. The completed cord assembly

shall be visually inspected for workmanship and miscellaneous defects.

4.5.4 Continuity. The finished cord shall be tested for continuity using a potential of not more than 10

volts. A suitable indicator such as a flashlight bulb shall be placed in the circuit.

4.5.5 DC resistance. DC resistance shall be measured in accordance with FED-STD-228, method

6021.1, to determine compliance with 3.9.1. An equivalent ac resistance measuring instrument may be

used as an alternative to method 6021.1.

4.5.6 Dielectric strength and insulation resistance. An instantaneous potential of 500 volts dc

(350 volts rms) shall be applied for not less than 5 seconds between each conductor and the remaining

conductor or conductors connected together. Immediately after the dielectric-strength test, the insulation

resistance shall be measured with a galvanometer or other approved instrument, using a dc potential of

not less than 125 nor more than 500 volts applied for 1 minute between each conductor and the

remaining conductor or conductors connected together. If a dc potential of 500 volts is used for the

insulation-resistance measurement, the 500-volt dielectric-strength test may be omitted. The insulation-

resistance test may be terminated after 5 seconds if the galvanometer has ceased fluctuating and the

reading indicates that a steady or increasing insulation-resistance value has been obtained. The 500 volt

dielectric strength test and the insulation resistance test may be combined by using a megger or other

approved instrument which generates 500 volts dc. The voltage of the megger shall be continuously

applied for not less than 5 seconds between each conductor and all other conductors connected together.

If a correction factor is employed, the manufacturer shall demonstrate that it is accurate for the compound

used. If the requirement for insulation resistance cannot be met at ambient humidity conditions

exceeding 50% relative humidity, the sample units shall then be retested for acceptance at a relative

humidity of 50 � 10%.