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MCB and RCD mix and match of makes 536.4.203

Stewart Mason
Just wondering what peoples thoughts are to mixing makes of MCB's and RCD's in consumer units. I went to a callout the other night and the culprit was a faulty 61008 RCD. To get the power back on I replaced the faulty Item with a different make of 61008 RCD. The next day I raised a job to have the right make of RCD fitted. It turns out the QS at work isn't concerned about the incorrect make of RCD and is more concerned about IP ratings being met. Am I right in wanting to fit the correct make of RCD?


What would you code this as on a EICR?
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    mapj1:

    in general the risk of mix and match is small, if it is done properly, and you are not right on the edge of PSSC spec. or relying on co-ordination of cascaded breakers.




    Very good advice from mapj1. If I was designing the protections system those are the aspects I would be concerned with (and in that order). If the MCBs and RCDs meet the standards and have the same characteristics there should be little to worry about, particularly as no designer in their right mind would spec breakers right on the edge of their PSSC (though it has been done by some....).

    The maker's type testing will generally only confirm the breaking characteristics of the CB and not the coordination which will be achieved through review of the different CB tripping curves, unless the CB/RCD combination is specifically sold as a coordinated pair. However, as mapj1 says, you may want to ensure you cover yourself as the manufacturers are unlikely to confirm that mixing someone else's breakers is satisfactory - why would they when it will impact sales?

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    mapj1:

    in general the risk of mix and match is small, if it is done properly, and you are not right on the edge of PSSC spec. or relying on co-ordination of cascaded breakers.




    Very good advice from mapj1. If I was designing the protections system those are the aspects I would be concerned with (and in that order). If the MCBs and RCDs meet the standards and have the same characteristics there should be little to worry about, particularly as no designer in their right mind would spec breakers right on the edge of their PSSC (though it has been done by some....).

    The maker's type testing will generally only confirm the breaking characteristics of the CB and not the coordination which will be achieved through review of the different CB tripping curves, unless the CB/RCD combination is specifically sold as a coordinated pair. However, as mapj1 says, you may want to ensure you cover yourself as the manufacturers are unlikely to confirm that mixing someone else's breakers is satisfactory - why would they when it will impact sales?

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