Re: Happened to me as well!
Electricians? Over the years I've come across an alarming number of them that have no idea what they are doing, both in industry and domestic environments. It seems they memorise just enough of the current regs. to get though their exams then forget everything.
Oh, including one who was muttering about the three phase motor he had to fit, as it was going in the wrong direction. When I said offhand "You've probably swapped two of the phases", his dismissive reply was "What difference does that make?"
Yet I'm not considered capable of adding a spur to a domestic ring main.