To be slightly pedantic, ALL tasks require a risk assessment. Where I think you're coming from on this is when do the findings of the assessment become significant and therefore must be recorded as per Reg 3 MHSW Regs? With my Inspectors hat on, my view was that any activity which had a risk of anything more than a trivial injury should have a documented assessment and the scope of that assessment should be proportionate to the potential level of harm and the likelihood.

No they don't. What they do say is that, if you have 5 or more employees, then the significant FINDINGS of the assessments should be recorded I tend to agree, but common sense isn't common practice. Some say that it's common sense not to put your hands into some unguarded machinery, but it still happens. And describing something as an "everyday task" can be somewhat vague too. To my mind, it's all about being proportionate to the actual level of risk. Should you have a documented risk assessment for turning on a light switch? No. Should you have a risk assessment which includes management of the fixed electrical installation? Yes. Think about the worst case scenario and, should the worst happen, how would you be able to justify to the chap in the wig and the gown what you have or haven't done?