Table 41.1 Assumed Touch Voltage

ProMbrooke:

Well, I'm prepared to show my inference in great length, for the world to see, for the benefit of all humanity. :) Hiding the technical reasoning is both a crime and unethical when used to make what is used as law all over the globe. And I know why the IEC has gone into hiding technical aspects: because AFDDs are just the start to a long marketing concept. If you can mandated it, then it will sell. But that is for another thread.

[yes - I've been waiting for news on the AFDD thing...?]


I agree that the ideal standard would come with clear explanation of the reasoning behind it - though not necessarily in the same document. That would help avoid poorly founded rules appearing in the first place, make it easier to contest ones that do slip through, improve understanding of the purpose of rules and so of what consequences any considered deviations might have, and possibly help a later generation of standards-makers who've forgotten the original reasoning.

However, it would doubtless take a lot more work to give clear explanations of the typically messy problems involved, e.g. where a standard is a compromise between various national practices. Perhaps it would be enough to have clear minutes of all discussions that result in changes, rather than having to produce a nicely illustrated and described work like this TR 1200-413. Minutes wouldn't have to identify the parties, but just the arguments and choices.

On the other hand, journals are increasingly wanting authors of articles to declare any interests that might affect their opinions, and - for the reasons you've given - there's as much or more reason to care about this with standards. So perhaps it would be better to require more detail of the people present, their allegiances, and their side in the decisions. This gets more foggy with international bodies that take representatives from countries rather than directly from organizations. One sees less clearly who's pulling the strings to sway a country's view, unless it becomes appallingly obvious as with the ms-oxml & ISO case. (Not to mention the non-proportionality of representation of population when countries have populations from under a million up to hundreds (and more) of millions.)

The money side is a trouble, too. Standards end up out of reach for most except the companies that have to have them. They typically refer to many others, which in turn refer, so that many have to be bought. Years ago I took a course about one standard from its main contributor, who had a slide showing the many-inch tower of paper you would have to buy in order to have this standard with all its parts and the other standards that it depends on: he referred to the organization that produced it by making a slow, heavy circular motion with his hand, explaining that he was turning a money-making machine (he was a German-speaker - perhaps it's an established gesture).  Everyone I know who's contributing to IEC standards is paid by their employer, which also then pays for the IEC standards it uses. Perhaps I'm unrealistic to think the remaining costs should be low enough to be easily covered by e.g. countries paying a small amount, so that all the standards (besides the details of how they arose) could be freely viewed by anyone... BS7671 is actually cheap, due to its application, history, etc.; but buying all its parts from IEC would very much not be.  There are many other standards that don't have a convenient, cheapish national compilation of the parts.


Interesting points on the times and voltages.  I can't let myself get properly started on that now, as I'll take too long.  The chosen approach in IEC is much about simplicity of defining and verifying the requirements (e.g. loop-test, fuse/breaker curve). 

ProMbrooke:

Well, I'm prepared to show my inference in great length, for the world to see, for the benefit of all humanity. :) Hiding the technical reasoning is both a crime and unethical when used to make what is used as law all over the globe. And I know why the IEC has gone into hiding technical aspects: because AFDDs are just the start to a long marketing concept. If you can mandated it, then it will sell. But that is for another thread.

[yes - I've been waiting for news on the AFDD thing...?]


I agree that the ideal standard would come with clear explanation of the reasoning behind it - though not necessarily in the same document. That would help avoid poorly founded rules appearing in the first place, make it easier to contest ones that do slip through, improve understanding of the purpose of rules and so of what consequences any considered deviations might have, and possibly help a later generation of standards-makers who've forgotten the original reasoning.

However, it would doubtless take a lot more work to give clear explanations of the typically messy problems involved, e.g. where a standard is a compromise between various national practices. Perhaps it would be enough to have clear minutes of all discussions that result in changes, rather than having to produce a nicely illustrated and described work like this TR 1200-413. Minutes wouldn't have to identify the parties, but just the arguments and choices.

On the other hand, journals are increasingly wanting authors of articles to declare any interests that might affect their opinions, and - for the reasons you've given - there's as much or more reason to care about this with standards. So perhaps it would be better to require more detail of the people present, their allegiances, and their side in the decisions. This gets more foggy with international bodies that take representatives from countries rather than directly from organizations. One sees less clearly who's pulling the strings to sway a country's view, unless it becomes appallingly obvious as with the ms-oxml & ISO case. (Not to mention the non-proportionality of representation of population when countries have populations from under a million up to hundreds (and more) of millions.)

The money side is a trouble, too. Standards end up out of reach for most except the companies that have to have them. They typically refer to many others, which in turn refer, so that many have to be bought. Years ago I took a course about one standard from its main contributor, who had a slide showing the many-inch tower of paper you would have to buy in order to have this standard with all its parts and the other standards that it depends on: he referred to the organization that produced it by making a slow, heavy circular motion with his hand, explaining that he was turning a money-making machine (he was a German-speaker - perhaps it's an established gesture).  Everyone I know who's contributing to IEC standards is paid by their employer, which also then pays for the IEC standards it uses. Perhaps I'm unrealistic to think the remaining costs should be low enough to be easily covered by e.g. countries paying a small amount, so that all the standards (besides the details of how they arose) could be freely viewed by anyone... BS7671 is actually cheap, due to its application, history, etc.; but buying all its parts from IEC would very much not be.  There are many other standards that don't have a convenient, cheapish national compilation of the parts.


Interesting points on the times and voltages.  I can't let myself get properly started on that now, as I'll take too long.  The chosen approach in IEC is much about simplicity of defining and verifying the requirements (e.g. loop-test, fuse/breaker curve).