New busbar for split-load consumer unit converted to all RCBO

[DetlefSchmitz]

I think a lot of issues with Consumer Units arise from the idea that a busbar is an essential part of a CU. In, for example, Germany, all the CUs I have looked into were wired between MCBs using suitable wires. No issues with alignment of components were created. The 'type-tested' concept seems to be a purely UK thing, at least in the Eric type of approach. I could well be incorrect about that of course.

 

[JohnW2]

The MCB/RCD/RCBOs hold it in place, not the clips

This is acceptable?

It's certainly very common. I have many CUs in my house, and every one has a bus bar held only by the terminals in the breakers. In fact, it would be very wrong to rely on electrical connections to provide mechanical support for the devices. One would normally expect (and I was going to write) that mechanical support is provided by the DIN rail, but you now go on to say ...

The issue is that behind the breakers is no full DIN rail, only the top ridge of a standard DIN rail. In the unit's design,

Whilst, as above, having a bus bar only 'held in place' by the devices is very common / 'acceptable', I would personally say that a CU which doesn't properly mechanically support the devices was not acceptable!

Kind Regards, John

 

[JohnW2]

That wouldn't dissuade me from having a go at succeeding where they failed; having seen some meter board builds I wouldn't place universally great faith in their mechanical competence

In purely 'mechanical' terms I agree. However, if someone else (hethr an Octopus engineer or anyone else) had tried and failed to remove a cutout fuse, I personally would definitely not (and would advise anyone else not to) attempt to get it out by more 'mechanically competent' methods (let alone 'brute force'!) - these things have been known to disintegrate, exposing goodness knows what1

Kind Regards, John

 

[JohnW2]

When I saw the OP last night, I knew the thread was going to end up like this

... and (now three pages further on!) how right you were

Kind Regards, John

 

[SUNRAY]

Whilst, as above, having a bus bar only 'held in place' by the devices is very common / 'acceptable', I would personally say that a CU which doesn't properly mechanically support the devices was not acceptable!

Kind Regards, John

That is actually a very, very, common arrangement. If not currently certainly historically.

 

[JohnW2]

That is actually a very, very, common arrangement. If not currently certainly historically.

Hmmm. What is the reason/justification for not having the devices properly mounted on a DIN rail?

Kind Regards, John

 

[ericmark]

Back in around 2000 some one said to me that devices needed to be type tested when in the control of an ordinary person. But I have not found where it says that.

Clearly if DIY'ing then your not classed as an ordinary person, you have extra skills, but in real terms who cares unless something goes wrong, things like the Emma Shaw case are thankfully rare, and I certainly considered things after the case was reported, and realised I had also been using an electricians mate for things which one could say he was not trained to do.

I made up many panels to control machines, and I decided what was safe, maybe I was wrong, but no one was injured, so there was no court case to determine if I had made errors.

It is the same with every trade, I remember back in the 80's talking to a mechanic after an axle had come out of a wagon, the court said the mechanic involved had not used a proper spanner, but had used a chisel to tighten the bearing nuts, but everyone did back then, few garages had the special box spanners for the job.

As tradesmen we have to make the call, there are two considerations, is it safe, and if I do it will it return to bite me. We see so many jobs worth, but in real terms it can be just that, so no one can say that's OK go ahead, if it does not follow the letter of the regulations we should point it out, however you need to also use some common sense.

 

[EFLImpudence]

Hmmm. What is the reason/justification for not having the devices properly mounted on a DIN rail?

Gravity - and then the cover will secure them adequately?

Ability to change one MCB more easily?

 

[JohnW2]

Back in around 2000 some one said to me that devices needed to be type tested when in the control of an ordinary person. But I have not found where it says that.

I think you'll find that the only mention of "type tested" in BS7671 is (and always has been) in relation to the definition of a "Consumer Unit".

I further think (but maybe I'm wrong?) that the only significance of this is probably that IF it is 'type tested' with a DP incomer (hence a 'CU') and IF it is a single-phase supply no greater than 200, 'under the control of ordinary persons', then it is acceptable (per 536.4.201) for it to contain devices rated at 6kA.

However, I am not aware of anything in BS7671 which says that a DB in a domestic setting, 'under the control of ordinary persons', has to be a CU. It therefore seems that a DB which does not qualify as a CU is still acceptable and, as above, I think the only consequence of having such a DB is that 6kA devices might not be considered adequate.

Clearly if DIY'ing then your not classed as an ordinary person, you have extra skills ....

I don't think that is what BS7671 means by 'ordinary persons' (or the opposite) . In any event, what matters is not who does the work (DIyer or 'electrician') but, rather, who is 'in control of' the DB after the work has been done - and, even when the work is DIY'd, the DB will usually be, at least potentially, 'under the control' of persons other than the one who did the work.

Kind Regards, John

 

[markyd1]

So, was he qualified or COMPETENT to do the job?....Gave up following the thread after he nearly burst out crying

 

[JohnW2]

Gravity .....

I doubt whether the people who invented DIN rails envisioned one 'half' of them being used to just hang things off!

... and then the cover will secure them adequately?

Is that a serious suggestion? All of the devices, complete with busbar, might fall off together when the over was removed? I admit that, even with no rail at all, some bits of chewing gum or Blu Tack might well prevent them falling out when the cover was removed, but ...... !!

Ability to change one MCB more easily?

How often does one need to do that, and how much 'less easy' would it be if the devices were properly attached to the rail?

Kind Regards, John

 

[JohnW2]

So, was he qualified or COMPETENT to do the job?....Gave up following the thread after he nearly burst out crying

I think we can be fairly sure that he isn't qualified - and we can only speculate about competence.

Was it really your intention to trigger the three or so pages of oh-so-familiar 'discussion' that, as someone commented at the time, was an almost inevitable consequence of your question/comment?

Kind Regards, John

 

[markyd1]

Not really my intention, but I knew it would happen

 

[JohnW2]

Not really my intention, but I knew it would happen

I've often made the same mistake, but the older I get, the more I try to modify by behaviour when I "know what will happen" if I don't!

Kind Regards, John

 

[markyd1]

No......love watching everyone on here going at it