Mixed brand MCBs and EICR coding

[kai]

That main switch looks very lop-sided to me - not a good sign.

The newer Wylex blanks look like these.

Busbars in a modern Wylex Consumer Unit.

• kai
• 21 Feb 2016

They clip on the din rail, and securely shield the busbar tabs too.

 

[Iggifer]

Yea it was being pushed out of place by that Wylex breaker. It all popped back into place when I changed the breaker and cover

 

[JohnW2]

non-compliant with 530.3..4 unless you were absolutely certain that it wasn't compliant with BS EN 61493-3

Among other things, 61439-3 requires type testing.

Hmmmm. So when BS7671 effectively says that ("if under the control or ordinary persons") it must EITHER be a ('type tested', per definition) CU OR be compliant with BS EN 61493-3, what do you think it is trying to say??

Kind Regards, John

 

[JohnW2]

Also where the heat is produced, and where the magnetic fields are created, and where the parts that are sensitive to heat or magnetic fields.

Undoubtedly all theoretically true. However, I again have to ask whether anyone has ever seen, or even heard of, a case in which mixed-make protective devices was regarded as the cause of a serious malfunction?

Kind Regards, John

 

[ericmark]

We have all seen images like this in trade mags. It would clearly affect any device pressed up against it. However it would be very hard to prove if damage like this was caused by faulty design, faulty fitting, or a miss match.

This is easier clearly the buzz bar was not making good contact as to if that was due to the MCB's not matching it's hard to tell.

There are four reasons for a bad connection on the buzz bar.
One buzz bar not in line with the MCB so it presses against the bar but does not grip the bar likely due to miss match.
Two the screw simply not tightened.
Three the buzz bar wrong side of clamp.
Screws binding in MCB so shows tight on torque driver but not tight on the buzz bar.

The problem is after the event the screws binding will likely slack off so can't see they were binding, the buzz bar will warp so can't see it was a miss match, and buzz bar annealed so even if it was tight it now appears slack, the only one you can positivity identify is wrong side of buzz bar. So in real terms we can only guess.

 

[JohnW2]

We have all seen images like this in trade mags. It would clearly affect any device pressed up against it. However it would be very hard to prove if damage like this was caused by faulty design, faulty fitting, or a miss match.

Yes, in an individual case it would be impossible to know. However, if one had the data, one could look at it statistically - to ascertain whether such happenings were more common when two adjacent devices were of different makes - and, despite (as stillp will tell us) the theoretical possibilities, I very much doubt that such would prove to be the case.

Whatever the answer to that, I would be extremely surprised if any problems (if any) due to mixed-make (but mechanically compatible) devices did not fade into total insignificance in comparison with problems due to imperfect connections to the devices (even if all of the same, 'correct', make).

Kind Regards, John

 

[ericmark]

Returning to original question although clearly wrong to mix types, I could not justify giving even a C3 code if no other fault. However I would want to carefully inspect and this raises the question with an EICR have you got the time to remove MCB's for inspection?

 

[EFLImpudence]

https://www.tritonshowers.co.uk/power-showers
http://www.wickes.co.uk/Products/Bathrooms/Showers-and-Accessories/Shower-Pumps/c/1001039

 

[ban-all-sheds]

Several times in this topic I've read things along the lines of "assuming they physically fit", or "has anybody heard of problems arising from mixing of different makes which fit".

The thing is you just don't know if they fit properly, or not, or if there are other compatibility issues.

You've been asked to inspect an installation, and comment on it's condition, safety, remedial work needed or advised, etc.

You must not ignore a pick'n'mix CU, you must not just note it as an observation, and even if you do have the time to poke around inside the CU, removing and replacing devices, then in the context of professional liability, duty of care etc, do you really have the expertise to say for certain that it's not, or could not become dangerous?

You have to say "this is unsatisfactory, and must be properly investigated because there is a possibility that it is genuinely dangerous".

 

[ban-all-sheds]

https://www.tritonshowers.co.uk/power-showers
http://www.wickes.co.uk/Products/Bathrooms/Showers-and-Accessories/Shower-Pumps/c/1001039

Err....?

 

[Robin0577]

The only reason that I used the caveat "assuming they physically fit" in the original question was to exclude from the discussion other problems caused by not physically fitting, e.g bent bus bars and butchered casings, which could be coded in their own right. as inadequate connections or IP breeches. I did not intend to imply that physically fitting makes it ok.

 

[EFLImpudence]

Err....?

Bugger, I've got the wrong thread again.

I assumed you would all know what I meant.

 

[stillp]

I would be extremely surprised if any problems (if any) due to mixed-make (but mechanically compatible) devices did not fade into total insignificance in comparison with problems due to imperfect connections to the devices (even if all of the same, 'correct', make).

Yes, your theory is probably correct, but, if parts come from different manufacturers, you cannot assume that they are 'mechanically compatible' just because it is possible to fit them together.

despite (as stillp will tell us) the theoretical possibilities

OK, what about the known (perhaps not to you) facts?

 

[JohnD]

Sometimes the parts are made by the same company, to the same specification, and just have a different name on them

I'm thinking of MEM MCBs, which might be labelled MEM, Eaton, Talisman (?) and I think at least one other.

Weren't WYLEX Standard MCBs at one time made under contract by GE to Wylex spec?

There ought really to be a compatibility reference doc.

 

[stillp]

So when BS7671 effectively says that ("if under the control or ordinary persons") it must EITHER be a ('type tested', per definition) CU OR be compliant with BS EN 61493-3, what do you think it is trying to say??

I don't know, but both the definition in BS7671, and BS EN 61439-3:2012. Low-voltage switchgear and controlgear assemblies. Distribution boards intended to be operated by ordinary persons (DBO), require that a consumer unit is type-tested.