For industrial electrical installations the need for compliance with standards is vital in order to ensure such things as occupational health and safety in the workplace, security and safety of earthing systems, functional safety, longevity of performance and continuity of supply for plant and equipment. The same criteria which are applied to the plethora of electrical equipment should also be considered as applicable to cable glands, in order for systems to be installed and operated reliably.

During the formative years of the rapidly expanding power generation industry in all over world, the acute need for a common standard reference document that could address cable gland requirements was recognised, and from this GDCD 190 was created. Latterly in the 1970's BS 4121 was superseded by BS 6121 with the introduction of the metric system of measurement across Europe. Majority of cable gland designs around the BS 6121 standard. However in particular the area where some manufacturer don't comply with BS 6121 are the maximum bore dimensions (Table-I) through the cable gland, the wall thicknesses as a result of the bore size discrepancies, and the sealing ranges that differ considerably from the standard.

European standard for Cable Glands EN 50262 was published in September 1998. The new standard is very different from the previous British standards BS 6121 in some important respects. A new IEC standard for “Cable Glands for Electrical Installations”, IEC 62444, was published in 2010 and in time this will be adopted in several countries across the world, including Australia. This new standard could have a profound impact on users and manufacturers, especially those who discover for the first time that the products they have previously used have not been tested to any current standards. IEC 62444 is similar to EN 50262 in that it is also a performance based standard, allowing manufacturers to produce cable glands of varying degrees of robustness some of which may be more suited to light industrial applications such as factory automation, whilst others may be more applicable to medium and heavy duty industrial electrical installations, such as power generation and distribution.

A circular test mandrel is loaded until the pull force is in accordance with the values given in Table 2 column “Cable retention”. For test mandrels which are not circular in shape, i.e. where non-circular cables are being simulated, their cross-sectional area shall be determined, and the diameter of a circular cable of the same cross-sectional area shall be calculated. The test values shall be appropriate to the nearest circular test mandrel size. For cable glands with sealing systems comprising two or more seals with different sizes, the mandrel shall be stepped appropriately. The test values shall be appropriate to the largest test mandrel diameter. The test mandrel is marked when unloaded so that any displacement relative to the cable gland can be easily detected. The load is maintained for 5 min and at the end of this period the displacement shall not exceed 3mm when unloaded. The test is repeated using new samples and a test mandrel equivalent to the maximum value of the sealing range of the cable gland as declared by the manufacturer or supplier, with the test value of the relevant maximum cable diameter specified in Table 2.

Compliance is checked by the following tests. For cable glands with a sealing system in accordance with 6.5.1, a test mandrel equivalent to the minimum value of the anchorage range of the cable gland as declared by the manufacturer or supplier is fixed to the sample. For cable glands with a sealing system in accordance with 6.5.2, a test mandrel equivalent to the minimum value of the anchorage range of the smallest orifice of the cable gland is fixed into the smallest orifice of the sample, and each remaining orifice is plugged with a plug equivalent to the minimum value of its sealing range. The test mandrel is marked when unloaded so that any displacement relative to the cable gland can be easily detected. The test mandrel is pulled 50 times for a duration of 1 Second without jerks in the direction of its axis with the relevant pull force specified in Table 2. At the end of this period the displacement shall not exceed 2mm. This measurement is to be carried out after unloading the force from the test mandrel. A typical arrangement for the cable anchorage pull test is shown in Figure 2.

The sample with the test mandrel is then mounted onto the test arrangement for the cable anchorage twist test as shown in Figure 3. The test mandrel is marked when unloaded so that any displacement can be easily detected and then is subjected for 1 min to the torque as shown in Table 3. During this test the test mandrel shall not turn by more than an angle of 45°. The pull and twist tests shall be repeated using a test mandrel equivalent to the maximum value of the anchorage range of the cable gland as declared by the manufacturer or supplier with the test value of the relevant maximum cable diameter specified in Tables 2 and 3.

Two samples, each consisting of two cable glands, are assembled. In the first sample, the cable glands are fitted, one at each end, to a cable 300 mm long, with the maximum over armour diameter as declared by the manufacturer or supplier. In the second sample the cable glands are fitted, one at each end, to a cable 300 mm long, with the minimum over armour diameter as declared by the manufacturer or supplier. For each sample, one cable gland is fixed and the other cable gland is loaded in accordance with the appropriate value given in Table 2. The cable is marked so that any displacement relative to each cable gland can be easily detected. The load is maintained for 5 min and at the end of this period the displacement shall not exceed 3 mm at either cable gland. A typical arrangement for cable anchorage test for armoured cable is shown in Figure 4. Following the test, the samples of cable glands classified in accordance with 6.3.1.2 shall then be subjected to the test in accordance with 10.2. Following the test, the samples of cable glands classified in accordance with 6.3.1.3 are then subjected to the test in accordance with 10.2 followed by the test in accordance with 10.3.2.

Compliance is checked by the following test. For cable glands with a sealing system in accordance with 6.5.1, a test mandrel equivalent to the minimum value of the sealing range of the cable gland as declared by the manufacturer or supplier is fixed to the sample and then the test is carried out at the minimum temperature in accordance with 8.5 or lower if declared by the manufacturer. For cable glands with a sealing system in accordance with 6.5.2, a test mandrel equivalent to the minimum value of the sealing range of the smallest orifice of the cable gland is fixed into the smallest orifice of the sample, and each remaining orifice is plugged with a plug equivalent to the minimum value of its sealing range. The test is carried out at the minimum temperature in accordance with 8.5 or lower if declared by the manufacturer. Prior to the impact test the samples shall be placed in a refrigerator for 8 h minimum. The test temperature tolerance is ± 2 °C.

The testing can be done – inside the refrigerator at the declared minimum temperature, or – outside the refrigerator at ambient temperature (20 ± 5) °C if the cable gland previously was cooled down to the declared minimum temperature in accordance with 8.5 minus 5 °C and the impact is carried out within (15 ± 2) after the cable gland was removed from the refrigerator. For example, if the declared temperature is –20 °C and the test is carried out outside the refrigerator, then the cooling temperature shall be –25 °C. The point of impact shall be the place considered to be weakest. The sample shall be mounted on a steel base so that – the direction of impact is perpendicular to the surface being tested if it is flat, or perpendicular to the tangent of the surface at the point of impact if it is not flat; – there is no movement of the cable gland support which could influence the test results. The mass shall be fitted with an impact head of hardened steel in the form of a hemisphere of 25 mm diameter. The base shall have a mass of at least 20 kg or be rigidly fixed or inserted into the floor. A typical arrangement for the impact test is shown in Figure 5. The sample is subjected to the impact energy as given in Table 4 according to the category declared by the manufacturer or supplier.