ASTM-B787/B787M:04(R2020) pdf free download – Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation.
8 .4.1 Average of Results Obtained on All Wires Tested—The minimum elongation required shall be reduced in numerical value 5 (for example, from 30 to 25 %) from the numerical requirements for the wire before stranding.
8.4.2 Results Obtained on bull victual Vires—The elongation of individual wires shall he reduced in numerical value 15 from the minimum requirements before stranding (that is. 10 in addition to the 5 allowed in 8.4.1), hut in no case shall the elongation of any individual wire be less than 5 %.
8.5 In the event that the requirements prescribed in .4.2 are met but those prescribed in 8.4.1 are not met, a retest shall be permitted wherein all wires of the conductor shall be tested for the purpose of final determination of conformance to 8.4.
8.6 Elongation tests to determine compliance shall not be made on the conductor as a unit.
8.7 If a tinning or lead-alloy-coating test is required, it shall be made on the wires prior to stranding.
9. Physical and Electrical Tests of Conductors Stranded of Hard-Drawn or Medium-Hard Drawn Vires
9.1 Tests for the physical and electrical properties of wires composing conductors made from hard-drawn or medium- hard-drawn wires, uncoated or coated, shall he made before hut not after stranding.
9.2 At the option of the purchaser, ension and elongation tests on hard-drawn and medium-hard-drawn wires, uncoated or coated, before stranding may he waived, and the completed hard-drawn and medium-hard-drawn conductors may be tested as a unit. The breaking strength of the hare conductors so tested shall he at least 90 % of the total of the specified minimum breaking strengths of the component wires. The maximum breaking strength of conductors made from medium-hard- drawn wires, uncoated or coated, shall be not greater than the sum of the specified maximum breaking strengths of the component wires. The minimum breaking strengths of wires shall he calculated using specified nominal diameters and specified minimum tensile strengths. The maximum breaking strengths of wires shall be calculated using nominal diameters and specified maximum tensile strengths. The free length between grips of the test specimen shall be not less than 24 in. (610 mm), and care shall be taken to ensure that the wires in the conductor are evenly gripped during the test (Explanatory Note 6).
9.3 When requested by the purchaser at the time of placing the order, tension tests on hard-drawn and medium-hard-drawn wires, uncoated or coated, before stranding or as a unit may he waived and tests made on wires removed from the completed conductor. The test limits, based on a 10-in. (254-mm) gage length. for such tests shall be specified by the purchaser in the placing of individual orders (Explanatory Note 5).
9.4 If a tinning test is required, it shall be made on the wires prior to stranding.