22www.cmp-products.com

CMPC A B L E G L A N D A N D C A B L E C O N N E C T I O N S P E C I A L I S T S

GETTING TO GRIPS WITH SOFT BEDDED CABLES

The increasing popularity of fire resistant and flame retardant cablesparticularly for safety focussed application such as oil & gasinstallations, refineries and chemical plants has led to a proliferationof what are commonly described as soft bedded cables. A generaldescription of a soft-bedded cable is one which employs materials,which exhibit, ‘significant cold flow’ characteristics, i.e. thermoplasticmaterials, which flow when subject to pressure at ambienttemperature. This bedding is the cable inner bedding, which in thecase of an armoured cable, is the part of the cable which enters theequipment.

Particular care should generally be taken when installing this type ofcable, so as to avoid cable damage due to over tightening of cablegland seals on the cable inner bedding. The selection of suitable cableglands to complement this type of cable construction is vital, as thetraditional compression seal cable gland is most likely to causeexcessive pressure on the part of the cable which is most vulnerable,leading to cable damage and potential long term di-electric problems.

An increased level of attention in this area may be required forinstallations in hazardous areas for obvious reasons which aresubsequently explained on page 60 of this catalogue.

A common method of addressing this problem is to use adisplacement seal, whereby the seal is gradually displaced as thecable gland is tightened, virtually eliminating any damage to cablebedding. The purpose of this design enables the user to control thelevel of displacement of the seal, ensuring a functional and moreimportantly, safe, seal is achieved without exerting any unduepressure onto the cable. An example of a cable gland utilising adisplacement seal on the cable inner bedding is illustrated below.The other important fact to note is that this also utilises a separatetightening action for the inner seal and the armour terminationcompartment, which is the differentiating feature compared withother cable gland designs.

Naturally, many factors influence the final method of installationincluding, environment, ambient temperatures, and the specificconstruction of the cable being used. CMP Products are always

willing to provide an expert assessment of a given application,drawing on many years experience of installation procedures,providing assurances that a safe solution is achieved every time.

INGRESS PROTECTION RATINGS

In the construction industry generally, a significant volume ofindustrial electrical installations require a high level of ingressprotection to be afforded from the equipment selected for theinstallation and the integrity of the installed apparatus.

Like other electrical equipment enclosures that are required to have averified Ingress Protection rating, cable glands are also required to betested to recognised standard test methods for Ingress Protection, asper the example table overleaf. The range of CMP cable glands havebeen 3rd party independently tested in order to validate their IngressProtection ratings, or I.P. ratings, in accordance with therequirements of EN60529 (IEC 60529). Some of the CMP cable gland

types have been tested to IP66, whilst other types have been testedto IP66, IP67 & IP68, to a depth of 10 metres*. Ingress Protectionshould not be confused with Deluge Protection (i.e. the DTS 01 : 91Deluge Test) which lays down a set of specific standard tests that aredifferent from those in the IEC 60529 standard. It should be notedthat none of the I.P. rating values taken from EN 60529 or IEC 60529are equivalent to the Deluge Test Specification DTS 01 : 91.

Further information on the subject of Deluge Protection can bereviewed on page 24 overleaf.

TECHNICAL&APPLICATIONINFORM

ATIONBASE