FED-STD-228A
Method 1421.1
18 April 2014
DIAMETER, ARMOR WIRE
1. SCOPE
1.1 This method is intended for use in determining of the wire used in the wire armor of insulated wire
and cable.
2. SPECIMEN
2.1 The specimen should be a piece of the bare armor wire at least 1 inch in length taken from the
inspection unit.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 Micrometer caliper graduated to read in 0.1 mil or 0.0001 inch and having flat surfaces on both
anvil and end of spindle, each approximately 0.25 inch in diameter. The surfaces of the anvil and spindle
shall be parallel to within 0.0001 inch.
3.1.2 Wiping cloth.
3.1.3 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. Any dirt, grease, or other extraneous
materials shall be removed from the specimen by means of the cloth and solvent. The micrometer caliper
shall be applied directly over the wire so that the anvil and spindle are just brought into contact with the
specimen in such a manner that the wire is not distorted. The criterion of contact is the initial
development of frictional resistance to movement of the specimen between the micrometer surfaces. The
diameter of the wire shall be read from the micrometer caliper scale and the value recorded. Three
measurements equally spaced along the length of the specimen shall be made.
4.2 The diameter measurements of the wire shall be made over any galvanizing or other metallic coating.
5. RESULTS
5.1 Unless otherwise specified in the detail specification, two specimens, one from each end of the
inspection unit, shall be tested.
5.2 The average diameter of the armor wire of the inspection unit shall be the average of the results
obtained from the specimens tested.
5.3 The minimum diameter of the armor wire of the inspection unit shall be the smallest of all values
averaged in determining the average diameter, 5.2.
5.4 The average diameter and minimum diameter of the armor wire of the inspection unit shall be
recorded to the nearest 0.1 mil or 0.0001 inch.
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