FED-STD-228A
Method 2031.1
18 APRIL 2014
FLEXIBILITY, COTTON COVERED ELECTRIC CORD
1. SCOPE
1.1 This method is intended for use in determining the ability of insulated wire, cord, and cable to bend
around cylindrical forms of relatively small diameter without damage. It is particularly applicable to cotton
covered flexible electric cord. The method is not applicable to asbestos covered cord or wire.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit at least 15 feet in length.
3. APPARATUS
3.1 The apparatus shall consist of a mandrel of the diameter required in 4.1.
4. PROCEDURE
4.1 Unless otherwise specified in the detail specification, the diameter of the mandrel shall be five times
the over-all diameter of the specimen.
4.2 Unless otherwise specified in the detail specification, the specimen shall be conditioned and tested at
a temperature of 23° ± 1°C. (73.5° ± 2°F).
4.3 The specimen shall be free from mechanical damage and shall not be bent or flexed until it has
reached the temperature required in 4.2. Handling and flexing of the specimen shall be reduced to the
absolute minimum necessary in conducting the test. The over-all diameter of the specimen shall be
measured as described in method 1111. The specimen shall be bent for ten close turns around the
mandrel required in 4.1. It shall then be unwound and rewound so that the outer side of the coil is
reversed to become the inner side. This operation shall be repeated for a total of three cycles. The coil
shall then be straightened and examined visually for breaks in the fibrous covering or conductor, flaking of
any impregnating compounds or finishing materials, damage to the insulation, or change in appearance
or evidence of strain. Cracking is not necessarily flaking of the finish.
4.4 Flat twin cable shall be bent on the minor axis of its cross section only. The minor diameter shall be
used in determining the size of the mandrel.
5. RESULTS
5.1 Unless otherwise specified in the detail specification, one specimen from each inspection unit shall
be tested.
5.2 Any breaking of the fibrous covering or conductors, damage to the insulation, appreciable change in
appearance, or evidence of strain of the specimen shall be recorded.
5.3 Flaking of the finished materials of the specimen shall be recorded.
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