We don't know the discontinuation dates of either the old RCBOs, or the old CUs. Possibly the old RCBOs were still current when the new CU was launched. They also might have tested old RCBOs in the new CU because of the stock levels of old RCBOs at their distributors - they wouldn't have wanted to issue credit notes.
Mixing new and old model RCBOs
- Thread starter fex10
- Start date
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Could they be being cagey because they've not tested the old and new styles in combinations for thermal effects? Higher-rated breakers carrying substantial currents for extended periods can become warm sometimes - Perhaps they've tested and satisfied themselves that a whole row of the new type are fine, but have not tested in combinations?
That's possible, and is more-or-less what stillp suggested. However, if that were the case, AFAICS it would be more a matter of 'formality' (and 'CYA') than engineering - is it really very credible that a whole row of new devices would be fine, and a whole row of old devices would be fine, but that a combination of new and old was 'not fine'?
Kind Regards, John
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You can't mix and match when using their "flexible" bus bar as they moved the hole.
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I just dry fitted the two types and they fit fine in this NH consumer unit.
It does sound like it's just a type approval issue. But I'll rather play safe so going for all new RCBOs.
Thanks for the advice!
Fair enough. That's obviously the 'correct' and ultra-cautious approach, but it presumably is going to cost you a substantial amount of money. How many 'old' RCBOs are you going to have to 'discard' and replace with newly bought ones?
Kind Regards, John
Highly unlikely I would say. But manufacturers these days are so worried about possible litigation that they often won't state something as being acceptable unless they've had it tested that specific way.
Five of them!
That sounds like around £140 to me. It would obviously be wrong for me to advocate anything other than the 'correct' approach, but that doesn't necessarily stop you 'reading between the lines' of what I write in an attempt to guess what I might do in your situation!
Kind Regards, John
John, I agree it's highly unlikely that there's any issue. I've still time to decide.
OTOH, they know the differences between the old and new designs, and none of us do.
Sure, that's strictly true, but I would like to think that we could apply a little bit of electrical/physics common sense/intuition. As I've said, if they are saying (as surely must be the case?) that a continuous row of 'new' RCBOs in a 'new' CU is OK, and also that (as they have seemingly told the OP) that a continuous row of 'old' RCBOs in a 'new' CU is also OK, then I think one would have to struggle to think of ways in which there could be a problem with a mixture. Very little is impossible, but that would seem extremely unlikely. FWIW, it certainly would not worry me personally, electrically speaking.
Kind Regards, John
I can think of a couple of ways in which a mixture of old and new might be unsatisfactory, but I'm not the manufacturer so my guess is as valueless as anyone else's.
I'd love to know the tech behind this? Curious.
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