I am well aware that this is pushing what can be DIY-ed.
I live in a student housing cooperative, and the two houses it comprises have an unused phone network running between them. The network was run through a CAT3 50- or 100-pair cable. The cable has a steel sheath inside, so I am assuming it is a direct burial between the buildings, running between both basements and underneath the pavement beneath the two buildings. The length of the run is probably 20-30 metres, but it's hard to tell because there's no way of knowing where exactly it goes underground.
What I hope to do is pull the individual conductors out of the cable, so that I am left with an empty sheath only. This I intend to use as the conduit for several CAT5e cables to replace the obsolete CAT3 wiring.
I've tried tying the conductors to a stick and pulling really hard, which didn't quite work out. If I pull on only a few conductors at a time, say up to 8 or so, I can pull out a few millimetres worth of conductor before they break from the strain. If I pull a larger number at a time, they only come out by a few millimetres, if at all, and it may be just the insulation stretching rather than the conductors sliding through. However, the conductors are very greasy, which I'm assuming is either to make them waterproof, or was perhaps used to pull them through originally (although it's more likely that this is a direct burial cable). So it seems like I should be able to pull the individual conductors out, pull some string or wire through, and use that to pull new cables through the remaining sheath.
Is doing this feasible at all? Would using an electric winch help, for example? Has anybody done anything similar before? If I can find the mechanical specifications of the cable, could I calculate how feasible it is (based on the maximum pulling force & the length of the cable, for example?)
I understand that the professional solution would be to dig up the cable and replace it.