Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment
These specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment. These specifications for a system of protective grounding utilizing copper cables are covered in four parts, as follows: clamps, ferrules, cables, and temporary protective grounds. Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification. The clamps shall be subject to design tests for determining mechanical torque strength and electrical short circuit capacity. The ferrules shall be tested for electrical short-circuit capacity and continuous current rating. The elastomer or thermoplastic making up the jacket of the flexible cable shall be tested according to the specified methods.
1.1 These specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment.
1.2 It is common practice for the users of protective grounding equipment to prepare complete instructions and regulations to govern in detail the correct use and maintenance of such equipment.
1.3 The uses and maintenance of this equipment are beyond the scope of these specifications.
1.4 These specifications for a system of protective grounding utilizing copper cables are covered in four parts, as follows:
Clamps for Temporary Protective Grounds
4 – 16
Ferrules for Temporary Protective Grounds
17 – 30
Cables for Temporary Protective Grounds
31 – 39
Protective Grounds (Complete Assembly With Clamps, Ferrules, and Cable)
40 – 52
1.5 Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification.
1.6 Currents presented in Table 1 are based upon cable melting times, as determined from equations by I. M. Onderdonk and are to used in situations involving an asymmetry value less than 20 % (X/R ≤ 1.8). See Appendix X1.
Note 1: TPG testing is done on complete assemblies. Assembly ratings assume the grade of lowest graded component (see 43.1.6).
1.6.1 Currents presented in Table 2 are based upon the values from EPRI Project RP2446 Computer Program RTGC “A Desktop Computer Program for Calculating Rating of Temporary Grounding Cables” and are to be used in situations involving an asymmetry value greater then 20 % (X/R ≧ 1.8), see Appendix X2.
Note 1: The above current values are based on electromechanical test values.
Note 2: Assemblies that have been subjected to these shall not be re-used.
Note 3: For use with currents exceeding 20 % asymmetry factor.
Note 4: See X2.7.2 for additional information.
Note 5: Alternate testing circuits are available for laboratories that cannot achieve the above requirements. See Appendix X2 for details.
Note 1: Table 1 represents the clamp and assembly ratings that existed prior to this revision. Table 2 represents new ratings now required for high X/R situations.
1.6.2 See Appendix X1 and Appendix X2 for a discussion of these topics.
1.7 The values stated in Newton-Meter units are to be regarded as the standard. The values in parentheses are the inch-pound units.
1.8 The following precautionary caveat pertains to the test method portions, Sections 12 and 25 of these specifications: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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