Shower circuit design.

We seem to be drifting slightly, but the type testing could be interesting.

There are only two or three sets of dimensions used for busbar and terminal positions among the various makes of MCBs, and the overall outline is very similar. They are almost all made in China from unknown manufacturers, and looking inside there is very little variation either. This is unsurprising as the function is identical as is the specification. The brand and labelling are printed on the outside, but all (presumably) have been type-tested to the same specification.

As many of you probably know, I am fairly cynical about many things, but with very good reason and as much understanding as I can achieve. I wonder how many factories these devices actually come from? I suggest that it may be only one or two, backed up by the noticeable fact that certain components get more difficult to source at the same time for several brands at once! Very curious.

As all of these devices have the same type-test, I cannot see what parameter could be different between brands to cause any problem. Mike says “eject metal” above, but this would surely happen whatever the containment, bus bar exact shape, and outer box material were used? They can all break the test 6kA (or 10kA) satisfactorily without failure, my question, therefore, is “what is the difference which prevents intermixing of brands, on the basis of product failure”? My cynic says “this is to keep the customer from buying spares from another source”, and that it is in BS7671 under manufacturer pressure. Trying to stop aftermarket parts for vehicles has been tested as illegal, surely the risk here is actually less, or potentially zero following above?

We seem to be drifting slightly, but the type testing could be interesting.

There are only two or three sets of dimensions used for busbar and terminal positions among the various makes of MCBs, and the overall outline is very similar. They are almost all made in China from unknown manufacturers, and looking inside there is very little variation either. This is unsurprising as the function is identical as is the specification. The brand and labelling are printed on the outside, but all (presumably) have been type-tested to the same specification.

As many of you probably know, I am fairly cynical about many things, but with very good reason and as much understanding as I can achieve. I wonder how many factories these devices actually come from? I suggest that it may be only one or two, backed up by the noticeable fact that certain components get more difficult to source at the same time for several brands at once! Very curious.

As all of these devices have the same type-test, I cannot see what parameter could be different between brands to cause any problem. Mike says “eject metal” above, but this would surely happen whatever the containment, bus bar exact shape, and outer box material were used? They can all break the test 6kA (or 10kA) satisfactorily without failure, my question, therefore, is “what is the difference which prevents intermixing of brands, on the basis of product failure”? My cynic says “this is to keep the customer from buying spares from another source”, and that it is in BS7671 under manufacturer pressure. Trying to stop aftermarket parts for vehicles has been tested as illegal, surely the risk here is actually less, or potentially zero following above?