In the UK, as far as the Health & Safety Executive goes, who are the people who will be hauling you up in court if your screwups cause injury or death, they go

In the UK, as far as the Health & Safety Executive goes, who are the people who will be hauling you up in court if your screwups cause injury or death, they go to great lengths to discourage working live if at all possible. That said, it is sometimes necessary. I've replaced a circuit protective device in a live electrical panel in a commercial setting before. As you point out, avoiding distraction is a very important factor. That means no chit-chat, no-one overlooking and critiquing what you're doing, noise to a minimum, all of the tools you'll need prepared up-front, etc.