The original question was quite straightdforward. Paraphrasing slightly - is it normal aviation practice? It sounds like the answer is no but there are occasions when there may be a sound operational need to do so. Is it a H & S matter? Probably, and it has nothing to do with aeroplanes - you don't find doors on the second floor of a factory that open to a sheer drop because the rules say you don't. And anyway, it's common sense - for everone's safety. Why sould aircraft not be subject to the same common sense rules where the same risks apply? Not all rules can be applied to aircraft but where they fit why not? Aircraft are just workplaces after all. When I sit in front of a radar it gets treated much the same way as a computer monitor where applicable. Seems fair to me.