Mixing new and old model RCBOs

[stillp]

Thermal and magnetic influences, for a start.

 

[JohnW2]

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.

Fair enough. I can think of some, too, but they are (at least IMO) so incredibly improbable that I don't think about them for too long. To put this all into perspective, there are undoubtedly countless CUs (may millions) in service that contain devices of different make, let alone different generations of the same make.

Do you know how this 'type testing' is done? Do they test most/all combinations of placements of different devices? I ask because I would probably be more potentially concerned about possible problems if, say, a 6A RCBO was sitting next to a 50A RCBO or MCB (or between two 32A ones) than I would if, say, two 6A, or two 32A, RCBOs of different 'generations' of the same make were adjacent.

Kind Regards, John

 

[stillp]

I ask because I would probably be more potentially concerned about possible problems if, say, a 6A RCBO was sitting next to a 50A RCBO or MCB (or between two 32A ones) than I would if, say, two 6A, or two 32A, RCBOs of different 'generations' of the same make were adjacent.

Perhaps John, but AFAIK you are not an electronic design engineer. Different generations from the same manufacturer might be as different as products from different manufacturers.

 

[AndyPRK]

Personally I think it's all about the busbars. Fixed bus bar with the U cuts can have mixed rcbo s.

 

[JohnW2]

I ask because I would probably be more potentially concerned about possible problems if, say, a 6A RCBO was sitting next to a 50A RCBO or MCB (or between two 32A ones) than I would if, say, two 6A, or two 32A, RCBOs of different 'generations' of the same make were adjacent.

Perhaps John, but AFAIK you are not an electronic design engineer. Different generations from the same manufacturer might be as different as products from different manufacturers.

No, I'm not an electronic design engineer, but you haven't answered my question (maybe you don't know the answer) about how 'type testing' is done. As you have said, the most likely (I suspect more-or-less the only) interactions between protective devices would presumably be thermal and/or electromagnetic in nature - and, in both cases, the current potentially flowing through nearby devices is surely going to be the most important factor in relation to any such interactions, even if the devices are of the same generation and same manufacturer, isn't it? I really don't think one needs to be an electronic design engineer to see that!

Kind Regards, John

 

[JohnW2]

Personally I think it's all about the busbars. Fixed bus bar with the U cuts can have mixed rcbo s.

Sure, mechanical/physical compatibility (or incompatibility) obvious trumps any of the more subtle/esoteric issues that have been discussed. As I wrote early on page 1 of this thread ...

Provided they are physically compatible (particularly in relation to terminal type/positions) ....

Kind Regards, John

 

[stillp]

you haven't answered my question (maybe you don't know the answer) about how 'type testing' is done

No, I don't know the answer, although I do have copies of the relevant standards. The manufacturer is responsible for the safety and correct operation of his products when in service, and he will test in a manner that gives him confidence in that performance. To make guesses is not normal practise in compliance engineering.

 

[JohnW2]

No, I don't know the answer, although I do have copies of the relevant standards. The manufacturer is responsible for the safety and correct operation of his products when in service, and he will test in a manner that gives him confidence in that performance. To make guesses is not normal practise in compliance engineering.

Quite - I would certainly hope that they don't work by guesswork. In that case, in the absence of any prohibitions about particular arrangements of devices within their CU, I would hope/imagine that their 'type testing' must somehow examine the long-term consequences of any possible arrangements of devices - such as a 6A one in-between full-loaded 32A and 50A ones?

Kind Regards, John

 

[stillp]

Quite - I would certainly hope that they don't work by guesswork. In that case, in the absence of any prohibitions about particular arrangements of devices within their CU, I would hope/imagine that their 'type testing' must somehow examine the long-term consequences of any possible arrangements of devices - such as a 6A one in-between full-loaded 32A and 50A ones?

Kind Regards, John

Why do you feel that it is acceptable for you to work by guesswork then? Even if you refer to it as intuition, hope, or imagination?

 

[JohnW2]

Why do you feel that it is acceptable for you to work by guesswork then? Even if you refer to it as intuition, hope, or imagination?

I'm not working by guesswork. I'm seeking reassurance (which I realise that you are unable to provide) (or, I suppose, the contrary!) that the manufacturer's aren't - specifically that their 'type testing' includes examination of situations which I think one could reasonably assume could carry at least as much risk of presenting problems as might arise by mixing 'new' and 'old' devices of the same manufacturer in the same CU. However, as you've said, you don't know the answer to that question.

Kind Regards, John

 

[stillp]

Their design verification needs to establish that, when used in accordance with their instructions, their devices function as intended. Any answer I provided as to how that design verification is performed would be specific to a particular manufacturer rather than a general practice. Once again though, you're guessing, although this time you describe it as assuming. The manufacturers know which situations present risks of malfunction, whereas you and I don't.

Actually I suppose I could tell you how some Chinese brands do it to their satisfaction - they copy the designs of reputable manufacturers!

 

[JohnW2]

... Once again though, you're guessing, although this time you describe it as assuming. The manufacturers know which situations present risks of malfunction, whereas you and I don't.

... and the manufacturers would be doing little more than guessing (or 'assuming', or whatever) "which situations present risks of malfunction" unless they tested all possible situations, wouldn't they? Being a manufacturer doesn't confer omniscience or mystical powers!

Kind Regards, John

 

[PBC_1966]

Actually I suppose I could tell you how some Chinese brands do it to their satisfaction - they copy the designs of reputable manufacturers!

But cheapen all the components to the point that any assumptions made about the original design being satisfactory can no longer be considered valid.

 

[stillp]

The usual problem is that they copy all the parts but use the wrong materials.

 

[fex10]

Wylex just emailed back saying that there is a slight difference in the form factor of the RCBOs, so the cover doesn't sit right! I've dry fitted and the cover sits fine and solid, so I'm not worried! They said aside from this they can be mixed.