ASTM F2249-24
Standard Specification for In-Service Test Methods for Temporary Grounding Jumper Assemblies Used on De-Energized Electric Power Lines and Equipment

Standard No.

ASTM F2249-24

Release Date

2024

Published By

American Society for Testing and Materials (ASTM)  US  /  ASTM

Status

Be replaced

Replace By

ASTM F2249-25

Latest

ASTM F2249-25

Introduction

Interpretation of the core content of the standard

ASTM F2249-24 specifies the on-site inspection requirements for temporary grounding jumper assemblies used to de-energize power lines, with the following highlights:

• Six mandatory defect determination criteria for visual inspection (Clause 5.1)
• Two test methods: DC resistance (≤10A) and AC impedance (≤10A) (Clause 7.3)
• Supplementary temperature difference test plan (Appendix X3)

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Comparison of key test parameters

Test method	Accuracy requirements	Determination formula	Applicable scenarios
DC resistance method	±5% current control	Rm=1.05RL+0.32mΩ	Conventional testing
AC impedance method	±5% current control	Zm=√(1.05RL+0.32)²+(XL)²	Inductive interference assessment
Temperature difference method	±1℃ infrared temperature measurement	ΔT≤15°F(8.3°C)	High current working condition

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Cable acceptance threshold system

The standard establishes acceptance criteria through a two-factor judgment model:

2. Terminal component resistance: 2Y=0.32mΩ (Clause 7.5.3)

Example: 2/0 AWG Class K cable at 20°C:

• Baseline resistance: 0.0826mΩ/ft (Table 1)
• Maximum allowable value for 10-foot cable: 1.1873mΩ (Table X1.3)

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Technological Evolution and Safety Considerations

Major Changes in the 2016 Edition: Added the temperature compensation formula RT2 = R20 * [1 + 0.00393 * (T2 - 20)] to address resistance conversion issues at different ambient temperatures (Clause 7.5.1.1).

Safety Redundancy Design: Resistors are permitted to increase their manufacturing tolerance by 5% + aging margin, but must pass a current-carrying capability verification of 200A/3 minutes (Appendix X3).

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Implementation Recommendations

1. Testing Cycle: In accordance with the IEEE 1048-2016 guidelines, it is recommended to test every 6 months in humid areas and annually in dry areas
2. Equipment Selection: DC testers with a range of 10A or above are preferred. AC tests require an anti-inductive layout rack
3. Defect Handling: Failed components must be physically destroyed (Clause 8.5) to prevent misuse