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IEC 61239 Live Working โ Portable Equipment for Earthing or Earthing and Short-Circuiting (WITHDRAWN)
🔴 Standard Status: IEC 61239 has been WITHDRAWN. This article provides an engineering analysis based on historical technical content. The current standard in this domain is IEC 61230. Please note the withdrawal status when referencing this information.
💡 Standard Overview: IEC 61239 formerly specified technical requirements and test methods for portable earthing and short-circuiting equipment used in live working. These devices provide reliable grounding of de-energized lines and equipment before maintenance work, serving as the last line of defense for personnel safety. The standard was officially withdrawn in 2011, with its content consolidated into IEC 61230.
1. Historical Background and Reasons for Withdrawal
IEC 61239 was first published in 1996 as an important component of the IEC live working tool standards suite. Portable earthing equipment includes earthing rods, earthing clamps, earthing cables, and short-circuiting devices, used to establish equipotential working zones in de-energized work areas.
The primary reason for withdrawal was the restructuring and consolidation of the standards system by IEC Technical Committee TC 78 (Live Working). IEC 61230 “Live Working — Portable Equipment for Earthing or Earthing and Short-Circuiting” was established as the unified standard for this domain. The withdrawal of IEC 61239 was not due to technical inadequacy but to eliminate standard duplication and simplify the certification framework. Core technical content was inherited by IEC 61230 in appendix or reference form.
⚠️ Engineering Note: Although IEC 61239 is withdrawn, legacy equipment certified under this standard may still be used during its service life in some countries. Users are advised to gradually transition to IEC 61230-compliant products and monitor their country’s transition timeline for withdrawn standards.
2. Technical Requirements Review
| Parameter | IEC 61239 Requirement | IEC 61230 (Current) Requirement |
|---|---|---|
| Rated short-circuit withstand | Graded by system fault level | Same grading, extended range |
| Earthing cable cross-section | ≥ 16 mm² (copper) | ≥ 16 mm² (copper), added Al cable rules |
| Minimum earthing rod length | Determined by system voltage | Essentially the same |
| Contact resistance | ≤ 0.5 mΩ | ≤ 0.5 mΩ (unchanged) |
| Mechanical strength | Clamp 2.5 kN tension | Clamp 2.5 kN + added dynamic load |
| Thermal stability test | I²t = rating, 1 application | I²t = rating, 3 applications |
2.1 Engineering Significance of Earthing Equipment
Portable earthing equipment is central to electrical work safety. Its operating principle is to install earthing sets on both sides of the work zone, creating an equipotential shielding area. In the event of accidental line energization, the earthing equipment provides a low-impedance shunt path for fault current, maintaining the potential difference within the work zone at safe levels. The standard requires earthing equipment impedance to be sufficiently low to ensure touch voltage during a fault does not exceed 50 V (AC) or 120 V (DC).
✅ Design Insight: The core design objective for earthing equipment is not “how low the resistance is” but “thermomechanical reliability of the fault current path.” Under short-circuit currents, earthing cables experience enormous electromagnetic repulsion forces — parallel conductors can experience forces of several thousand N/m. Therefore, earthing equipment must employ reliable clamping and securing arrangements to prevent cable ejection during faults. Locking-type earthing clamps and multiple parallel earthing cables to distribute electromagnetic forces are recommended.
3. Engineering Practice Under the Current Standard
According to the current standard IEC 61230, selection of portable earthing equipment should follow these steps: first calculate the maximum short-circuit current and fault duration at the installation point, then select earthing equipment with the corresponding rated short-circuit withstand capability. For 10 kV distribution systems, typical selection requirements are: short-circuit withstand current ≥ 20 kA (1 s), earthing cable ≥ 25 mm² copper stranded conductor.
Use and Maintenance: Portable earthing equipment must undergo visual inspection before each use, focusing on earthing clamp gripping force, insulation integrity of cables, and tightness of connection bolts. Comprehensive electrical testing should be performed annually, including contact resistance measurement and short-circuit withstand verification. Earthing equipment should be mandatorily retired after 5 years of service.
🔴 Critical Warning: Dedicated earthing clamps must always be used with portable earthing equipment. Wrapping cables around conductors is strictly prohibited — the contact resistance of such connections is unstable and can produce arcing during short-circuit conditions, leading to accidents. Furthermore, the installation sequence must be strictly followed: connect the earth end first, then the line end; removal sequence is the reverse.
4. Frequently Asked Questions
Q1: Can old products purchased under IEC 61239 still be used after withdrawal?
This depends on national regulations. Most countries allow continued use of previously certified products within their service life, but new procurement must comply with IEC 61230. Check local standard transition requirements.
Q2: What are the main differences between IEC 61230 and the withdrawn IEC 61239?
IEC 61230 integrates the content of IEC 61239 and IEC 611238, adding dynamic short-circuit test requirements, more detailed selection guidance, and more stringent thermal stability test repetition (increased from 1 to 3 applications).
Q3: Can portable earthing equipment be used on overhead lines?
Yes, but insulated operating sticks must be used for installation and removal. Overhead earthing operations should use dedicated earthing sticks to ensure adequate safety distance between the operator and live parts.
