I have several decades of experience in the design, testing and assessment of electrical and electronic products, in automotive, commercial, medical and domestic applications. However I would not have the arrogance to assume I could know more about how to use a product safely than the manufacturer of that product.
I don't think it's necessarily arrogance - MIs are necessarily very conservative, and assume no knowledge (and usually assume a high degree of risk-aversity), so as to cover all possible situations and users, but only you know the exact circumstances of your use, and your view about risk, particularly if (as you do) you have some relevant knowledge.
In all those decades of experience, have you never come across manufacturers' instructions which were either (a) wrong, or (b) there primarily in an attempt to 'cover' the manufacturer (sometimes in relation to theoretical risks which are of little/no relevance or concern to many users) or (c) as above, instructions which, in the interests of simplicity and widespread applicability, are blanket generic ones designed to apply to as wide a range of possible situations as possible (many of which will not be relevant to particular users) ??
Your medication example is quite a good one. Instructions/warnings for medications such as you mentioned are, in the interests of simplicity (and 'CYA'!) quite often 'fail safe' simplifications of a much more complicated reality. If one does know and understand the answers to the questions you were asking about (the reason for the instruction, and the possible consequences of not obeying it etc.) one will often discover, for example, that the instruction is only relevant to a subset of the population, and if one knows that one is not in that subset, then complying with the instruction is therefore unnecessary. In other cases, an understanding of the reason etc. will enable one to know that the two medications may be taken closer together than the 'blanket instruction' suggests provided that the dose of one or both is adjusted accordingly.
The documentation ('instructions') for a medication provided for prescribers (as opposed to patients/users) includes two sections, one 'Contraindications' and the other 'Warnings/Precautions'. Only the former contains "thou shalt not" (or "shalt") statements; there are usually few, if any, of these, and they relate to situations which things almost universally ill-advised/dangerous. The later section is invariably much longer, containing explanations of the nature of possible problems/risks and, where appropriate, information about the types of patient in which they may be relevant, so that the prescriber can make a judgement in relation to the situation concerned. However, many/most of those will appear as simple "thou shalt not" or "thou shalt" statements in the instructions for patients.
Have you never found, for example, a printed circuit that has tracked between line and neutral or between line and earth after some years' use?
I have, but I'm not sure of the relevance to this discussion. Are you perhaps suggesting that one cannot rely on a Class Ii item to remain safe indefinitely?
Kind Regards, John
