Hard hats in belfries A few thoughts on H&S some of which may be controversial.
My professional background is hanging very heavy things above peoples heads on a regular basis so risk assessments have been my life for the last 15 years, so I believe that I am competent to comment. That said I have a reputation for being pragmatic and not just doing things for the sake of "the rules"
First thing is that H&S is everyones individual responsibility, not the Church, not the Diocese so if YOU perceive a risk, mitigate against it. I have personally worked with several bell hangers and have been appalled at the apparent indifference to safety with the excuse that we have always done it this way and everyone's been OK so far. I did kick off on one occasion when a volunteer turned up to help with an augmentation wearing flip flops, I won the argument on that one and he was sent home to change his footwear.
Regarding hard hats and bump hats, I would default to always wearing protection, there are so many frame bolts and bits of hard metal sticking out all over the place to cause injury, if power tools are in use, eye protection should be mandatory, drills are a grey area but angle grinders or power saws absolutely, you only have one pair of eyes. If the hard hat gets in the way take it off but be extra careful when moving around and working under others and put it back on as soon as possible.
To sum up, it is your responsibility to keep yourself safe, and not to endanger others, so pause and assess the situation first, even if it is only mentally and don't take unnecessary risks, things don't go wrong very often but when they do it can be devastating to the victim and their family.