I did this with Electric wires that needed to break and freak out during a windstorm,
My method:
1. Loft static curves to make tubes (make sure you have plenty of curve segments),
2. Create nCloth from said tubes (use a preset like Solid Rubber to start with),
3. use a transform constraint on each end to pin to locators (in this case to the Hydro Poles)
4. Create a Component nConstraint to join the 2 tubes you want to break (1 for 1 on the Verts of each)
5. Animate the strength off when you want them to break,
What's nice about this method is that if the client wants you to have the wire / rope break at a different time you have full control with animation on the strength of the constraint.
Now if you wanted to get extra tech then you could (in theory, not tested) use a particle simulation with instance to have debris flying at the wire, then use tearable surface nConstraints with the instances being nRigid surfaces to have everything dynamically break. Hell, you could even use the built in wind of the nuculus solver with rand() or animation on it to simulate wind gusts!
nCloth is amazing, I use dynamic curves allot as well (especially as goals for nParticles), but for any kind of rigid sims I tend to allays use nCloth (or Houdini, but we won't go there right now, heh.). :)
