MIL-DTL-55668D
NATIONAL CONFERENCE STANDARDS LABORATORIES (NCSL)
-
General Requirements for Calibration of Measuring and Test
NCSL Z540.3
Equipment
(Copies of this document are available from https://www.ncsli.org or from the National Conference of
Standards Laboratories (NCSL), 2995 Wilderness Place, Suite 107, Boulder, CO 80301-5404.)
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO)
ISO 10012-1
-Quality Assurance Requirements forMeasurement
Equipment / Metrological Confirmation System for
Measuring Equipment.
(Copies of these documents are available online at https://www.iso.ch or from the International
Organization for Standardization American National Standards Institute, 11 West 42nd Street, 13th Floor,
New York, NY 10036.)
2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict
between the text of this document and the references cited herein, the text of this document takes
precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a
specific exemption has been obtained.
3. REQUIREMENTS
3.1 First article. The cords furnished under this specification shall be products which have been tested to
and have passed the first article inspection. First article approval is valid only on the contract under
which it is granted, unless extended by the government to another contract (see 6.4).
3.2 Conductors.
3.2.1 Stranded wire. Each stranded wire shall be the equivalent of No. 26 American Wire Gauge (AWG)
and shall consist of 26 strands of No. 40 AWG wire having a cross-sectional area of 9.9 circular mils and
stranded with a .25 inch (6.35 mm) nominal, .38 inch (9.65 mm) maximum, unidirectional left-hand lay.
The diameter of the stranded conductor shall be approximately .019 inch (.483 mm). Each strand shall
be tinned, soft or drawn and annealed cadmium-copper alloy having a 1 percent, nominal, cadmium
content and a minimum conductivity of 85 percent.
3.2.1.1 Tin-coating. Each strand shall be tin-coated with commercially pure tin. The tin-coating,
3.2.1.2 Stranded wire tensile strength and elongation. When tested as specified in 4.7.2.2, the tensile
strength and elongation of the coated strands, removed from the wires of insulated conductors prior to
cabling, shall be as follows:
Elongation in 10 inches (254 mm)
Tensile strength
40,000 psi (min.)
13 percent (min.)
3.2.1.3 Stranded wire resistance. Each strand shall have a direct current (dc) resistance of not more
than 1.27 ohms per foot. The dc resistance of the No. 26 stranded conductor shall be not more than
.0556 ohms per foot. Resistance values should be measured at or corrected to 20 ºC when tested in
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