Yes "Ring Main" is often used when "Ring Final" is actually the correct term, for ring main there are two types 1/ wiring out under our roads/streets and 2/ at a generating plant etc. But so long as we know what is actually meant then fair enough. Spur is another one often ill used.
Live is another often used wrongly.
But Hey Ho, in all walks of life words are often used wrongly/
Usually there is terms in common usage, technical terms and legal meanings. Quite often those three are quite different so I feel we need to try and live with that.
Nobody speaks perfik at all times in all ways, but as long as we make ourselves understood and try our best the fair go says I. There are lots of such anomalies