I haven't done it but hear are 2 sugestions.. look over all the threads in dynamic's on this board.. and animation. You might find the ansers there..

the other thing is for something that will not streach any. make a couple of qubes in a strait line. pasive ridged bodys for the end qubes that will be atached some whare. Active ridged bodys for all the inbetween ones. Use pin constraints under the dynamics menu, betwean each. Apply gravity to the qubes. now the qubes will be hiden in the render.. make a tube of some sort for your power lines.. and there are more than a couple of ways to atach the vertex or CV's to each cube for deformations..
this is what I can remember from simler post.. use at own risk.