As far as I am aware you need to be lv authorised to work on cut-out, including removing or replacing main fuse. Even then I was only allowed to work on out going side, different authorisation for incoming. Remember next fuse could well be 400 or 500 amp, main problem is fault arc, not electric shock, hence all clothing worn when working on live equipment is arc proof, and face mask and gauntlets worn. Previous poster right to say many types of cut-out not to be worked on live, espevially metal-clad ones. Having said all that, if the fuse was removed by known competent sparks, who also would not touch one of it looked dodgy, we would usually turn a blind eye. Sometimes when some one phoned fault desk and said 80 amp fuse had blown and needed replacing, question would be asked "how do you know what size fuse it is"?