FED-STD-228A
Method 2041.1
18 APRIL 2014
FLEXIBILITY, FIBROUS COVERINGS
1. SCOPE
1.1 This method is intended for use in determining the resistance to breakage of the yarns of fibrous
coverings of insulated wire and cable. It is particularly applicable to wires and cables of the building type.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit 24 ± ½ inch in length.
3. APPARATUS
3.1 The apparatus shall consist of a mandrel of the diameter required in table I of method 8221.
4. PROCEDURE
4.1 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).
4.2 The specimen shall be free from mechanical damage and shall not be bent or flexed until it has
reached the temperature specified in 4.1. Handling and flexing of the specimen shall be reduced to the
absolute minimum necessary in conducting the test. The specimen shall then be bent around a mandrel
of the diameter required in table I of method 8221. If the wire or cable is size No. 2 AWG or smaller, as
many turns shall be made about the mandrel as will permit it to conform closely to the mandrel with a 2 to
21/2 inch straight length of the specimen at each end. If the size of the wire or cable is larger than No. 2
AWG, a simple U-turn shall be made about the mandrel. The specimen shall be examined for broken
yarns in the fibrous covering both before and after removal from the mandrel. Examination shall also be
made for any flaking of the finishing material from the wire or cable as a result of the bending test, without
actual rubbing of the wire. Cracking is not necessarily flaking of the finish.
4.3 Flat twin cable shall be bent on the minor axis of its cross section only.
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 yarns in the fibrous covering of the specimen shall be recorded.
5.2.1 For wraps or servings, the type of yarn broken shall be recorded.
5.3 Any flaking of the finishing materials of the specimen shall be recorded.
5.4 The flexibility of the fibrous covering of the inspection unit shall be the results obtained from the
specimen or specimens tested.
5.5 The temperature of the test shall be recorded.
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