General Cabling And Wiring Information - BT Inspiration Installation & Maintenance Manual

General cabling and wiring information

Do not exceed the following resistance limit when connecting extensions to the CCU (0.5 mm tinned copper
conductor).
100 ohms or 500 metres for Featurephone extensions
200 ohms or 1.4 Km for standard 2-wire telephone extensions
336 ohms or 2 kilometres for 2-wire extension connected to extension position 22.
Great care should be taken when selecting the cable routes to ensure that the cabling complies with current
cabling requirements.
The extension and ISDN line cables must be of twisted-pair construction using insulated tinned copper wires
of nominal 0.5 mm cross-sectional area. It is important that this size and type of wire is used as incorrect
types could result in unreliable connections.
The extension and ISDN line cables enter the CCU at the bottom left-hand side of the CCU when viewed
from the front of the case. Remove the punch-outs and pass the cables through the cable entry hole in the
CCU case. The cables should then be passed through the cable retaining straps until adjacent to the relevant
connectors.
There are punch-outs for the ISDN and V24 connectors.
The cables should remain sheathed inside the CCU housing within reach of the connector. Guide the cables
neatly into the channel space between the connector and the CCU case side, ensuring that there is sufficient
clearance between the cables and the CCU case lid.
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