FED-STD-228A
Method 1441.1
18 APRIL 2014
CIRCUMFERENCE
1. SCOPE
1.1 This method is intended for use in determining the circumference of insulated wire or cable. It is
applicable to the determination of the circumference of finished cable, insulated wires, bare wires,
conductors, circumference over sheaths, etc., with a circumference of 3 inches or less, when the
circumference is required or when it is desirable to calculate the diameter from the circumference.
2. SPECIMEN
2.1 The specimen should be a piece of the insulated wire, cable, conductor, etc., at least 12 inches in
length taken from the inspection unit.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 Fine wire or thread with a length approximately 10 times the nominal circumference of the
specimen.
3.1.2 Convenient equipment for wrapping the wire or thread under a given tension around the specimen.
3.1.3 Convenient equipment for measuring the length of wire or thread which is wrapped around the
specimen to an accuracy of 0.1 inch.
3.1.4 Satisfactory equipment for controlling the tension of the wire or thread during wrapping and for
measuring the length of thread or wire in a given number of turns. Satisfactory equipment is shown on
figure 1441.
3.1.5 The apparatus described in method 1018 for determining the diameter of the thread.
3.1.6 Wiping cloth.
3.1.7 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. Any fiber, saturants, or other extraneous
materials shall be removed from the specimen by means of the cloth and solvent. The specimen shall be
placed in the testing apparatus and one end of the thread or wire attached to it by means of a chuck. The
other end of the thread shall be placed over the pulley and attached to the 10-gram weight, which moves
along a calibrated scale. The scale shall be calibrated so as to indicate the length of the thread wound
around the specimen. At least 10 complete turns of the thread or wire shall be wrapped around the
specimen under a load of 10 grams, and the number of turns recorded as N.
4.2 The wraps of thread shall be just in contact with each other, without any overlapping. The length of
the N turns of thread shall be read from the scale and the value recorded as L.
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