My extensions were installed by BT using the following convention:- 2 solid blue 3 solid green 5 solid orange They were taken off upstream of the master socket at a line block . Can anyone tell me the likely installation year(s)?
On older installations (pre-1980) cream or grey cables were used. They contained conductors coloured blue to pin 2, orange to pin 5, brown to pin 3 and green to pin 4 (if used), on some conversions green was used for pin 3 and brown for pin 4. Additional Bells are wired between pin 3 (orange/white) and pin 5 (white/blue).