I always just thought that we use rings for mains in order to get double the current-carrying capacity for no extra cost of additional wire.
It’s amazing what rodents will do. Janet kept my old Toyota in the garage for many years after I could no longer drive and in the end the rats moved in and ate all the electrical wiring. Years before that the rats ate all the control cables that belonged to a lawn mower stored in the small shed over the winter time. Now we have an organic deterrent - the "Thomas device" - who killed six rats in a couple of months around July/August, a few years ago. After that Thomas just looked at Janet as if to say, "I’m completely full-up" - "couldn’t manage another rodent."
Regarding rats electrocuting themselves - I have often been asked about birds landing on high voltage cables. Rats or birds are fine as long as they don’t establish a current path for the newly discovered high energy source to get to the planet. The energy source is called ‘potential energy’, in the terminology of physics, and in laymen’s slangy terminology popularly known very approximately as ‘voltage’. And understandably the universal dumping ground around here that we use for for all loose electrical energy, is the so-called ‘earth’. Once this path between the high potential energy point and the planet earth itself becomes established then suddenly your bird/rat/victim is well and truly done-for/fried. Now what might save the rat or bird aside from simply not having such an unwise path around is a good pair of insulating gloves or boots or a mat to stand on and that’s all it takes to avoid death.
Pondering on what Alex was saying, one thing that I really don’t like at all is the possibility of rats eating through one ring mains conductor alone. If the rats ate enough copper to completely disconnect a socket or something then we would know about it because something would stop working. But if it’s only partial, then there is the possibility that the damage would not be noticed and so then the users would go on unawares but losing the double current rating effect, which is not so good. I need to think more about that.
