Cable retention testing: Verifying strain relief and anchorage performance

In order to ensure maximum safety, we test the ability of our transits to withstand pull forces. The standard requirements for securing the position of a cable or pipe may mention cable retention, strain relief, anchorage or pull resistance, and they vary depending on application and cable type.

Specific requirements

Special arrangements may have unique requirements not found in codes or standards. There are, for example, hanging cables for towers or heavy cables with expansion loops causing pull loads to seals.

For compression type cable entry systems, the cable construction has great impact. The outer jacket material and texture affect the friction, and the solidness of a cable affects the compression force.

Verification of performance

The pull-out tests are used to evaluate tensile strength and to verify the performance of the sealing system when it is exposed to an external force.

Here are some common standards, requirements and other results from tests of Roxtec products.

Certified ratings

• ATEX/IECEx (IEC 60079-0). Compression type cable glands and cable entry system shall prevent slippage for 25 percent of a force 20 X cable OD in mm expressed in newton. Test method: Static load 6 h after ageing procedure. Requirement <6 mm slip.
• North American standards for conduit, tubing and cable fittings (UL514B/CSA 22.2 No. 18.3-12, (-04)). Test method: Static load 5 min. Requirement <3.2 mm slip.

Claimed rating

Roxtec cable transit devices cannot be certified to gland standards such as EN 50262/A1/A2 and IEC 62444 per definition. However, internal tests have been carried out following the methods of these standards. Roxtec products based on modules longer or equal to 30 mm meet cable anchorage Type B and C. Test method: Static load 5 min. Requirement <3 mm slip.

Constant pressure tightness in underground applications where cables may be bent or pulled. Test method: Installation of product in sleeve with cables or mandrels. Verification of maximum tension force.

Internal test equipment

Our in-house computerized equipment, Mecmesin MultiTest 50-I (up to 50 kN), allows for both static long- and short-term tests (hours/minutes), dynamic tests/jerks (seconds), as well as force-displacement testing with diagram showing the actual force required until a cable slips.

General comments

We carry out tests after the ordinary 24h settling time following valid installation instructions. Roxtec products are used in different ways, for a great variety of applications and with different types of cables, so it is impossible to fix a figure for what retention a Roxtec system can provide. For a specific cable exact values can only be obtained by a test in the intended system and configuration.

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