Strata Community Association (the strata managers’ professional body) says this in its “Who’s responsible …” document:
Any pipe, cable, telephone, television, internet wires, ducting, plugs, electrical wiring, light fitting, power point sockets or the like that is for the exclusive use of the lot, then if it breaks within the lot it is an Owners responsibility to repair.
Any pipe, cable, telephone, television or internet wiring, ducting, plugs, electrical wiring, light fitting, power point sockets or the like that services more than one lot, if it breaks outside the lot or in a wall, floor or ceiling that abuts to either common property or another lot it is an Owners Corporations responsibility to repair.
The strata manager’s the one whose got it wrong. Although it doesn’t spell that out succinctly, if the cabling is in the common property ceiling/floor, then it’s not in the lot. If it’s not in the lot, it’s not the owner’s responsibility.
The part of the cable that’s in common property is owners corp responsibility, until the point that it enters lot property, regardless of how many lots it services. The same principle applies to water pipes.
By the way, there’s an electrical and fire safety issue here and that alone should tell you that the perished cabling can’t be lot owner’s responsibility.
If the strata manager still disagrees, arrange a mediation at Fair Trading with a view to a Section 232 order at NCAT for failure to fulfil a responsibility. That should sort them out.