Ian:

I would say thats a good thing you stumbled on that and made your neighbour aware. There may be a few more places like yours with cables burning up if the same installer used the same brand of cable and fastened the cable up the same way.

Couple questions though.. Was it all burnt only at one staple / strap or was the cable burning at every point at which it was stapled / strapped?
Also, you mentioned " G.E skinny" breakers. What comes to mind are G.E "THQP" type... I am just curious as a friend of mine just bought a place and it has these breakers installed. Are they of the " no trip" design or prone to failure???
Just curious..

A.D