In my industry days is was always considered necessary that an electrician did not work alone, and my guys rarely do. I prefer them to pull the main fuse, and sit on a rubber mat, as much as we shouldn't be doing the fuse pulling, my own opinion is that this is the only real way of conforming with ESQR, plus we have found some nasties like wire in place of fuses, so in my opinion we are doing the DNO a favour by checking the main fuse. It is also my opinion that my staff are competent enough to work live, it's not hard, and they have the kit to do it safely, but I leave the choice to them as I'm rarely on-site these days. For larger jobs, we do also get isolators fitted where time isn't a constraint.