Anyone know anything about electricity overhead cables supply?

We viewed a house that has a huge cable running across the garden which connects to the wall and other cables spur off it and supply the other houses (Its in the countryside) - obviously theres no underground cables but this seems a bit dangerous - for examble, using a hosepipe in the garden could be lethal - any ideas?? Who would I contact to come and have a look? The supplier? All the cables look quite old too.