The standard internal telephone and voice distribution cable in the UK, built as twisted pairs of 0.5 mm solid copper under a thin PVC or LSF sheath. The CW1308 designation is a telecoms catalogue reference inherited from British Telecom, which is why installers quote it as though it were a standard. Pair counts from one upwards let the same cable serve a single extension or a riser feeding a whole floor.
Key applications
- Internal telephone extension wiring from the master socket onwards
- Voice riser and horizontal distribution in commercial buildings
- Cross-connection between distribution frames and krone blocks
- Door entry and intercom wiring
- Low-current signalling and control circuits
- Legacy analogue voice circuits and PBX extension wiring
Features and benefits
- Solid 0.5 mm copper conductors terminate reliably into insulation displacement connectors
- Standard telecoms pair colour code for fast identification on large pair counts
- Thin sheath keeps riser and trunking fill down on high pair counts
- LSF and LSZH sheath versions available for escape routes and public areas
- Polyester tape separator on the larger pair counts holds the lay stable
Specification notes and limitations
At 80 V working this is a telecommunications cable, not a mains cable, and it must be kept separated from power wiring in accordance with BS 7671. Ringing voltage on an analogue line can still give a noticeable shock, so treat live pairs with respect when jointing. In escape routes, stairwells and other areas where smoke and acid gas emission matters, specify an LSF or LSZH sheath rather than standard PVC.
