IEC 61138 Cables for Portable Earthing and Short-Circuiting Equipment

The International Electrotechnical Commission (IEC) standard "IEC 61138 Cables for portable grounding and shorting equipment" specifies requirements for flexible cables with ethylene propylene rubber, polyvinyl chloride, or silicone rubber insulation for portable grounding and shorting equipment. Because these types of cables are designed solely for grounding and shorting equipment, this standard does not include nominal voltages.

The types of cables covered by the IEC 61138 standard are vital for safely earthing and short-circuiting electrical installations during maintenance or emergency operations to protect personnel from electric shock or arc flash.

This standard applies to flexible, insulated and sheathed cables used at low and medium voltages in systems up to 36 kV. It includes:

• Electrical properties (such as current carrying capacity)
• Mechanical requirements (such as flexibility and tensile strength)
• Thermal performance (resistance to high operating temperatures)
• Resistance to environmental factors (such as UV, oil, ozone and flame)

The IEC 61138 standard essentially defines two main cable types:

• Type A cables: Used for low-voltage applications (generally 1 kV and below). They are lighter and more flexible. They are typically used in distribution networks.
• Type B cables: Used for high short-circuit current resistance. Used in higher voltage environments (up to 36 kV). Heavier and more robust.

Key testing and performance criteria include:

• Dielectric tests
• Conductor resistance
• Tensile strength and elongation
• Flame retardancy
• Flexural and bending resistance
• Thermal cycling and aging tests

The IEC 61138 standard is considered essential because it ensures the safety, reliability, and performance of cables used in portable grounding and short-circuiting equipment, which are critical tools for protecting electrical workers during maintenance or emergency situations. This standard is important for the following reasons:

• Protection of personnel against electric shock: When workers maintain or inspect high-voltage equipment, it must be discharged and grounded to prevent accidental energization. This standard specifies cables that reliably conduct fault currents to ground and protect workers from fatal electric shock.
• Preventing arc flashes and explosions: In the presence of unexpected voltages, poor-quality cables may not be able to carry short-circuit currents, leading to arcing or explosions. This standard ensures that cables can withstand thermal and mechanical stresses under fault conditions.
• Reliable performance under harsh conditions: The cables are typically used in outdoor or industrial environments (exposed to oil, UV light, moisture, and abrasion). The IEC 61138 standard includes environmental resistance tests that ensure long-term reliability.
• Standardization and compatibility: This standard ensures that equipment from different manufacturers is interchangeable and meets the same minimum safety and performance criteria. This is crucial for utilities, contractors, and emergency responders working with diverse systems.
• Defines test methods and requirements: This standard outlines uniform test procedures for:
  • Electrical conductivity
  • Thermal resistance
  • Mechanical durability

These tests ensure consistent quality control across global suppliers.

This standard is considered to be useful mainly for: electrical appliance manufacturers, power distribution units and the telecommunications sector.

The tests described in this standard are widely sought after because they ensure the safety of personnel performing maintenance on de-energized systems, promote standardization in the design and use of grounding cables, and reduce the risk of electrical accidents due to cable failure or poor material quality. Failure to comply with this standard significantly increases the risk of serious electrical accidents during service and maintenance operations.

The test methods described in this standard are defined in the following standards:

• IEC 60227-2 Polyvinyl chloride insulated cables for nominal voltages up to and including 450/750 Volts - Part 2: Test methods
• IEC 60245-2 Rubber-insulated cables - Nominal voltages up to and including 450/750 Volts - Part 2: Test methods
• IEC 60811 Electric and optical fibre cables - Test methods for non-metallic materials
• IEC 62230 Electric cables - Spark test method

In addition to the requirements in IEC 61138, mechanical requirements and marking requirements for complete equipment must also be considered. These requirements are included in IEC 61230.

Type testing generally refers to the tests that must be performed to demonstrate satisfactory performance characteristics for a cable type covered by this standard to meet its intended application. Once these tests have been performed, they will not need to be repeated unless changes are made to the cable materials, design, or type of manufacturing process that could alter the performance characteristics.

Sample testing refers to tests performed on samples of completed cable or components taken from a completed cable that are sufficient to verify that the finished product meets design specifications.

Routine testing refers to tests performed on all production cable lengths to demonstrate their integrity.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services to businesses in accordance with the IEC 61138 "Cables for Portable Grounding and Short-Circuit Equipment" standard.