BS 1363 13A Socket Continuous Max Load

This is undoubtedly an interesting discussion. It points out a number of defects with the standards system, and the use of these by manufacturers. I was having a discussion with a well-respected standards Engineer the other day, about the FACT that MCBs can become very hot at their nominal current, not even a current which will at some point cause tripping in some cases sufficient to cause the cases to brown and even become distorted. At one time (quite a long time ago) the cases were made of thermosetting plastic,  whereas I have just tested an new MK Sentry RCBO and the case is a thermoplastic and melts at about 200C or less. It is not labelled with a recycling type so identification is a bit difficult. I think it may well be uPVC, or a similar co-polymer, or possibly from the smell nylon. As you will be aware uPVC and nylon are easily formed by quite limited heat, typically plastic conduit.

All of these ratings, heating and other effects suggests a serious design problem, where the full operating envelope has not been considered properly. Our conversation was started because of the current note from manufacturers that they are unhappy with RCD current ratings not matching the maximum of the protected circuit protective devices. However whilst in Screwfix this morning there were various BG CUs on sale where the protected MCBs did not match this criterion!

It seems from all the comments above that many believe that the published ratings are not the ratings that can be used. This is a ridiculous conclusion, but whilst it may be true, this should not ever be the case, pointing out that specifications and standards are ALL totally unsatisfactory. I have no idea how to get this fixed, as manufacturers seem to be getting away with it, and using instructions to avoid any responsibility for this unsatisfactory situation. Any ideas? 

This is undoubtedly an interesting discussion. It points out a number of defects with the standards system, and the use of these by manufacturers. I was having a discussion with a well-respected standards Engineer the other day, about the FACT that MCBs can become very hot at their nominal current, not even a current which will at some point cause tripping in some cases sufficient to cause the cases to brown and even become distorted. At one time (quite a long time ago) the cases were made of thermosetting plastic,  whereas I have just tested an new MK Sentry RCBO and the case is a thermoplastic and melts at about 200C or less. It is not labelled with a recycling type so identification is a bit difficult. I think it may well be uPVC, or a similar co-polymer, or possibly from the smell nylon. As you will be aware uPVC and nylon are easily formed by quite limited heat, typically plastic conduit.

All of these ratings, heating and other effects suggests a serious design problem, where the full operating envelope has not been considered properly. Our conversation was started because of the current note from manufacturers that they are unhappy with RCD current ratings not matching the maximum of the protected circuit protective devices. However whilst in Screwfix this morning there were various BG CUs on sale where the protected MCBs did not match this criterion!

It seems from all the comments above that many believe that the published ratings are not the ratings that can be used. This is a ridiculous conclusion, but whilst it may be true, this should not ever be the case, pointing out that specifications and standards are ALL totally unsatisfactory. I have no idea how to get this fixed, as manufacturers seem to be getting away with it, and using instructions to avoid any responsibility for this unsatisfactory situation. Any ideas?