A puzzling one from today

[Sidewinder]

No Rob, it is a known scenario with some makes of RCBO, but, for the life of me now after a few beers, and a few VERY long and busy taxing days, I can't recall which ones.

 

[Kurt]

Eaton?

 

[Sidewinder]

Eaton?

Eaton / MEM sounds about right actually Kurt?

Anyone else got any thoughts?

 

[Rob_the_rich]

just spoke with contactum tech, they seem to think that there is an inductive load somewhere on the circuit which is holding the voltage up and delaying the trip. It could be the piezo-electric circuit in the hob/oven ignition. It might be that the cooker was not disconnected from the circuit (wired into cooker outlet?), they suggest disconnecting it and re-testing. They said that there is nothing wrong with the rcbo, since it passed both tests at the terminals (and therefore testing at the terminals is ok with this brand).

 

[M107]

just spoke with contactum tech, they seem to think that there is an inductive load somewhere on the circuit which is holding the voltage up and delaying the trip. It could be the piezo-electric circuit in the hob/oven ignition. It might be that the cooker was not disconnected from the circuit (wired into cooker outlet?), they suggest disconnecting it and re-testing. They said that there is nothing wrong with the rcbo, since it passed both tests at the terminals (and therefore testing at the terminals is ok with this brand).

Cooker circuit 6mm² T/E on 32a 30mA rcbo no cooker connected (using gas hob/oven) ccu with socket no neon. 

Well it is definitely a strange one, dropped in there last night as my mate had the carpets up, so we were able to run in tails for a new kitchen ring main. This gave me the chance to follow the route of the cooker circuit, the 6mm² runs from the board to the ccu & on to the outlet no deviations in route to other circuits & no joints or connections made on route.

 

[Rob_the_rich]

Sorry, missed that. so it does not run alongside other cables?

 

[M107]

It does, Ring , Lighting & a shower

 

[Lurch]

Now I have a feeling that these are from a faulty manufacturing batch. From what I can tell the Contactum and Techna RCBO's are the same as the ones @SBS Dave supplies (only mentioning it so he can check on this as well). I have just replaced a board and used the Techna RCBO's and I also had some issues with trip times being quite high on the B32 RCBO's.

I think this might need some looking into by the manufacturers. I would contact Contactum (contact 'em!) and bring this to their attention as I would suspect that other manufacturers using the same modules will be experiencing some issues. I have raised an issue with Techna but I am unable to visit site to swap the modules out yet so haven't done any further investigation.

 

[M107]

Will give Contactum a call tomorrow.

 

[SBS Dave]

Just to clarify the situation with regard the LiVE RCBO I sell.

This design was a Jovean & Rogy one in China, which was probably a European design and first certified by Intertek Semko AB in Sweden in 2005.

It has been sold in the UK under at least 10 brands and under dozens of brands around the world. After 12 years on the market, it is one of the most proven RCBOs around.

There are dozens of manufacturers of the model in China, all with their own production facilities and quality varies from Company to Company.

So, this is not a design problem, but a manufacturing problem with some Chinese Companies.

Techna sell this particular one, as do LiVE, TDline and a few others. I used to bring it in from China myself, before sourcing in the UK.

Contactum used to sell this, but it was replaced by their CPBR06 range, which I believe means 6KS ssc. Mine is rated at 10KA.

MK and Chint also used to sell it, both claiming it to be their own product, which caused them embarrassment, so they switched to another design.  

If M107 installed an older CU, it may have been the same as mine and it is easy to tell. Mine has L & N output terminals above one another, whereas the new Contactum model has the output terminals side by side. However, the new Contactum model is also a generic design, used by quite a few Companies, under their own brand name.

With regards to M107's problem, let me know if you want to try one of mine, M107 and I'll send you one FOC.

By the way, Lurch, I am not sure how much you paid for your Techna unit, but mine is £12.00 + VAT. Please let me know.

SBS Dave

 

[M107]

Its the new L & N side by side Contactum range Dave

No need to send one to try, but hanks for the offer.

I didn't get time to call Contactum today

 

[Lurch]

There are dozens of manufacturers of the model in China, all with their own production facilities and quality varies from Company to Company.

So, this is not a design problem, but a manufacturing problem with some Chinese Companies.

It would be interesting to see if any of the suppliers of the faulty units would manage to find a common supplier and issue a recall. I'm not sure how much head burying there will be though.

By the way, Lurch, I am not sure how much you paid for your Techna unit, but mine is £12.00 + VAT. Please let me know.

It was a similar price from memory, I did look at your units but as I already use Techna for other items as well I went with those, and I was fitting them in a type A board so I just stuck to my usual supply chain for this job.

 

[SBS Dave]

Hi Lurch,

Since the Contactum model is not the same one as mine, it looks as though it is Techna with the quality problem.

They will buy the finished article from a Chinese manufacturer, who assembles them from sub-assemblies manufactured by others.

So, either there was a batch of faulty sub-assemblies or there was poor quality control for some period of time on the assembly line.

I am not aware of any multiple failure rates across this RCBO model, but you may have more information than I have.

I checked the Techna website for details of their RCBO and also saw their range of Consumer Units, which does not include AMD3 metal boxes.

Neither do they show A type boards  and if they don't supply them, it begs the question "Into which A type board did you fit the Techna devices?"

I have battled with the "Mix & Match" argument for years, so it is heartening to meet another professional Installer, who is happy to do just that.

SBS Dave

 

[Lurch]

 it begs the question "Into which A type board did you fit the Techna devices?"

On this occasion, a Havells 8 way type A board. In hindsight I wish I would have just stuck the Havells RCBO's in as well for the hassle that this small job has caused for the sake of adding a couple of RCD's to existing circuits to cover additional sockets added.

As for mix & match, I also build control panels so I have spent years fitting all sorts of makes of MCB's into technically non-approved/type tested enclosures (manly Rittal AE boxes). If I am mixing and matching in a domestic consumer unit I will usually just make sure that the busbar terminals are aligned, but if it is a in a control panel then anything goes, bit of tri-rated and a couple of ferrules and away we go. The guidance is there from the manufacturers for arse covering, not for any technical reasons. I think you'd be hard pushed to argue that there is a problem but then again it is against manufacturers instructions (or some manufacturers instructions anyway). Works the other way as well I suppose, when I stick a row of SAK terminals in a Hager enclosure to extend some circuits are they all going to melt/explode? Dunno, maybe the part p police are camping out round the corner waiting for me?

 

[Sidewinder]

It's all down to type approval and the UP annexe to the standard for short circuit current rating.

The requirement is also there in EN 60204 but it is not as explicit as it is in the standard for UK consumer units.

 

[M107]

Just an update.......

Used this job for my assessment, turns out the issue with the failing trip time on the cooker circuit is potentially down to...................................RF disrupting the rcbo.

Passed the assessment by the way.........

 

[Blue Duck]

Just an update.......

Used this job for my assessment, turns out the issue with the failing trip time on the cooker circuit is potentially down to...................................RF disrupting the rcbo.

Passed the assessment by the way.........

RF....

WTGrape...

Are we going to be just installing RF resistant enclosures under the 18th??

TBH there is a lot of gubbins in an RCBO.

Well done BTW!  :happybunny:

 

[Tony S]

Just an update.......

Used this job for my assessment, turns out the issue with the failing trip time on the cooker circuit is potentially down to...................................RF disrupting the rcbo.

Passed the assessment by the way.........

Just wait until we get AFDD’s, they’re sensitive to HF RF interference. Eaton can now supply AFCI’s with a HAM designation if they are specified.

 

[Andy™]

maybe EIC's etc could be supplied with the devitations box pre-filled in with 'arc fault devices not fitted due to their known issues and unreliability and them not being proven to make the installation any more safe'

 

[Murdoch]

maybe EIC's etc could be supplied with the devitations box pre-filled in with 'arc fault devices not fitted due to their known issues and unreliability and them not being proven to make the installation any more safe'

Got a better idea ... ALL of just ignore the 18th Ed regs concerning these devices !