Older boards and availability/compatibility of devices

It used to be simpler - in the past we only really worried when then assembly somehow had to be grater than the sum of its parts - e.g. putting 6kA MCBs in a plastic box and then claiming the whole lot was good for 16kA prospective fault currents - leaving individual manufacturers free to device methods of achieving that (whether it be completely relying on backup protection from an upstream fuse, or allowing the MCB to fail catastrophically but contain all the resulting fragments within its own case, or allow the MCB to explode but contain everything within the outer enclosure) - in such cases taking an MCB from one system and putting it into a different system's case may well then not have the desired result.


Things do seem to have been tightened up with the 18th - I suspect it's related to the move from the old BS EN 60439 to the new BS EN 61439 and the changes to the way things are type tested - but I don't have the details behind that.


I guess there could be some incompatibilities between different manufacturer's systems - whether it be the amount of heat an MCB generates and how resistant it is to heat from neighbouring devices or bus-bars, or rotating bits on the sides of some MCBs (intended for clip on trips or RCD modules) might get fouled by similar but different bits on other manufacturer's devices, as well as the more obvious differences in terminal size/height/type etc.


I totally agree that it results in a very wasteful system - in materials, time and money - and probably back-fires on manufacturers in the long term as people would be far more willing to try new kinds of devices (A-type RCDs, SPDs, AFDDs etc) if they could reasonably be slotted into a spare way or two of an existing system rather than necessitating a complete replacement every time. I feel sure it should be possible to come up with a much more 'compatible' system  - at least for CUs and similar 'small' DBs - with resulting environmental and economic benefits all round.


  - Andy.

It used to be simpler - in the past we only really worried when then assembly somehow had to be grater than the sum of its parts - e.g. putting 6kA MCBs in a plastic box and then claiming the whole lot was good for 16kA prospective fault currents - leaving individual manufacturers free to device methods of achieving that (whether it be completely relying on backup protection from an upstream fuse, or allowing the MCB to fail catastrophically but contain all the resulting fragments within its own case, or allow the MCB to explode but contain everything within the outer enclosure) - in such cases taking an MCB from one system and putting it into a different system's case may well then not have the desired result.


Things do seem to have been tightened up with the 18th - I suspect it's related to the move from the old BS EN 60439 to the new BS EN 61439 and the changes to the way things are type tested - but I don't have the details behind that.


I guess there could be some incompatibilities between different manufacturer's systems - whether it be the amount of heat an MCB generates and how resistant it is to heat from neighbouring devices or bus-bars, or rotating bits on the sides of some MCBs (intended for clip on trips or RCD modules) might get fouled by similar but different bits on other manufacturer's devices, as well as the more obvious differences in terminal size/height/type etc.


I totally agree that it results in a very wasteful system - in materials, time and money - and probably back-fires on manufacturers in the long term as people would be far more willing to try new kinds of devices (A-type RCDs, SPDs, AFDDs etc) if they could reasonably be slotted into a spare way or two of an existing system rather than necessitating a complete replacement every time. I feel sure it should be possible to come up with a much more 'compatible' system  - at least for CUs and similar 'small' DBs - with resulting environmental and economic benefits all round.


  - Andy.