Interesting question. "Reasonable" is, of course, a word beloved of those who draft legislation - and I suppose it reflects the fact that it's very often impossible to be 'comprehensively prescriptive', so they deliberately leave it for judges and juries to exercise discretion (hopefully 'common sense'!) in deciding what is 'reasonable' in a particular situtionOne question I would ask is. ... Does what is considered "reasonable" change over time, even if the law itself stays the same? Are there any precedents on this question from fields other than electrics?
Indeed. In fact, Approved Doc P (the 'guide as to how to comply with Part P') essentially says that.Specifically, when part P was introduced everyone would have agreed that the then-current (16th with some ammendments IIRC) edition of BS7671 satisfied the “Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury.”
That's how it seems. They appear to take the view that what is "reasonable" is compliance with the current version of BS7671 at any point in time.However since then new versions of BS7671 has been published introducing a bunch of new requirements (RCD protection, resistance to premature collapse) and the "approved documents" have been updated to point to newer versions (though at the time of writing not the newest version). Does that mean that what was considered reasonable when Part P was introduced is no longer considered reasonable.
There's obviously scope for a fair bit of discussion of individual views about that! Some would undoubtedly say that if something were "reasonable" (in terms of safety) in 2005 or 2007, then it must still be 'reasonable' today. However, there are clearly limits to how far one can extend that argument back in time since, in almost all walks of life, there are things which would have been regarded as 'reasonable'/'acceptable' a few decades ago that would definitely not be so regarded today!
Kind Regards, John