FED-STD-228A
Method 3211.1
18 APRIL 2014
TENSILE STRENGTH AND ELONGAITON, SOFT OF ANNEALED CONDUCTORS
1. SCOPE
1.1 This method is intended for use in determining the tensile strength and elongation of soft of annealed
solid copper conductors or wires of stranded conductors of insulated wire and cable. It is applicable to
both coated and uncoated conductors.
2. SPECIMEN
2.1 The specimen should be the bare conductor or a wire from a stranded conductor removed from a
piece of the inspection unit at least 20 inches in length.
3. APPARATUS
3.1 The apparatus shall be as follows:
3.1.1 Testing machine. The testing machine shall meet the following requirements:
3.1.1.1 The machine shall be power-driven.
3.1.1.2 The applied tension shall be indicated by a dial, scale, or automatic recorder to within ± 1 percent
when properly calibrated.
3.1.1.3 The indicator shall remain at the point of maximum force after rupture of the specimen. A spring-
balanced type of machine is satisfactory if equipped to prevent recoil of the spring.
3.1.1.4 The rate of travel of the power-actuated grip shall be 10 ± 2 inches per minute under no load and
shall be uniform.
3.1.1.5 The machine, when used for a given specimen, should be of such capacity that the maximum
load required to break the specimen is not greater than 85 percent nor less than 15 percent of the rated
capacity.
3.1.1.6 The machine shall accommodate specimens of 10-inch bench length.
3.1.1.7 Grips. The grips of the machine shall be designed to produce as nearly as possible uniformly
distributed pure axial tension in the specimen. Grips shall be spool-type for specimens less than 0.208
inch in diameter, and wedge-type for specimens 0.208 inch and larger in diameter.
3.1.2 Steel scale graduated to 1/32 inch or finer, or its decimal equivalent.
4. PROCEDURE
4.1 Two parallel bench marks 10 ± 1/32 inch apart shall be placed on the specimen without damage to
the copper.
4.2 The diameter of the wire shall be measured as described in method 1421. Measurements shall be
made at nine places equally distributed between the bench marks, and the minimum value recorded as D.
107
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