2008-07-11
A cable must be properly fixed and supported throughout its length. In most cases, an armoured cable gland should not be used as a means of support.
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Failure to adequately support an armoured cable can produce a considerable strain at the made-off end with consequences including:
The gland plate is subjected to undue stress and becomes distorted. The situation can become worse if two or more unsupported armoured cables are terminated on a single gland plate.
The enclousure can become distorted or damaged.
Some or all of the steel wires of the armouring may become disengaged from the gland, producing a degradation of the earthing arrangements and a reduction in mechanical strength. Under adverse conditions the armouring can be pulled out of the gland putting strain on the conductor terminations and leaving the armour unearthed.
Solution
A cable gland nust not be subject to undue strain either due to the unsupported weight of the cable or due to a bend in the cable in the vicinity of the gland placing undue lateral strain on the gland (Regulations 522.8.4 and 522.8.5 refer).
A gland is a means of properly making-off a cable and is, in most cases, not intended to be a means of support. It should be ensured that cable glands are not subjected to any significant strai. The cable must be properly supported throughout its length. Cleats, saddle support, ties, etc must be properly selected and installed. The recommended minimum bending radius of the cable must be observed.
Regulation 522.8.4
Where the conductors or cables are not supported continuously due to the method of installation, they shall be supported by suitable means at appropriate intervals in such a manner that the conductors or cables do not suffer damage by their own weight.
Regulation 522.8.5
Every cable or conductor shall be supported in such a way that it is not exposed to undue mechanical strain and so that there is no appreciable mechanical strain on the terminations of the conductors, account being taken of mechanical strain imposed by the supported weight of the cable conductor itself.
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