This Defence Standard specifies telephone cables (external), which are to be utilised in telephone, telegraph, and allied systems for Ministry of Defence use.

a) Service requirements for telephone cables (internal) are specified in Def Stan 61-12 Part 12 Section 2.

b) Service requirements for field telephone cables are specified in Def Stan 61-12 Part 12 Section 3.

Table 1 to Table 4 of this section list the standard range of telephone cables (external) which selection shall be made-for-all new future requirements, including the maintenance of existing equipment whereever possible.

This Standard does not include a Table listing 'Items no longer to be provisioned'.

This Standard is to be invoked in all tenders or contracts for the items in Table 1 to Table 4. Any items supplied must be wholly in conformity with its requirements. For codification purposes this Standard is to be listed among the reference data for the items in Table 1 to Table 4.

This Standard has been agreed by all authorities concerned who are to implement it from its date of issue.

If this Standard should be found.' unsuitable for a particular requirement, the Director of Standardization shall be informed of the circumstances. Any enquiries regarding this Standard in relation to an invitation to tender or a contract in which it' is invoked should be addressed to the Quality Assurance Authority named in that invitation to tender or contract.

Users should note the following:

This Standard does not list any cables with overall screening. Requirements for such cables may be met by the use of the armoured cables listed in Table 2 where the screening is provided by the armouring.

Polyethylene sheathed cables are not affected by low temperatures but the PVC compounds used in the over-sheathing of armoured cables becomes increasingly stiff and brittle as their temperature decreases, with the result that if the cable is bent too sharply or is struck at temperatures in the region of 0oC or lower there is a risk of shattering the PVC component. To avoid the risk of damage during handling it is necessary that these cables should be installed only when both the cable and the ambient temperature are above 0oC, and have been so for the previous 24hours, or when precautions have been taken to maintain the cable above this temperature.

The standard range of telephone cables does not list any having more than 100 pairs of conductors. Requirements above this number are to be met by the use of two or more cables

The telephone cables listed in the standard range possess the following mechanical and electrical properties:

— The interstices are filed with compound which prevents the longitudinal transmission of water in the event of failure.