UK Inspection Report, Electric Shower, Merlin Gerin and Schneider MCBs

[Iain Stewart]

Hello,
We live in an old stone built ground floor flat, built in the 1880s. Obviously the consumer unit and cabling has been updated a number of times over the years by previous owners. One being the Local Authority who owned the property back in the 1960s -70s.

We have lived here for 25 years and decided to have an electrical inspection carried out by a local Electrician. He is a good honest guy, fully trained and qualified and a member of quite a few registered bodies. His report has shown only a couple of problem areas that should be addressed. Separate circuits for appliances, swapping circuits to the protected side of the consumer unit, updating sockets and light switches. He says although our consumer unit is older and the cabling is older there is no need change it or renew at this time but it is something we should think about for the future. He did have limited knowledge with regard to our particular make/model of consumer unit. (Young guy probably not born when our consumer unit was installed)

Now, our plan is to sell up in the new year and realising that this would be a huge upheaval and at a hefty cost we have decided to not take on the task.
However, we have hit a juncture. Our plumbing is such that we have only ever had an Electric Shower.
We wish to maintain this arrangement but have decided to upgrade the shower to a more powerful 10.5Kw unit as the old 7.5Kw shower has packed in and as you have no doubt guessed, this will involve a cable and MCB upgrade.

Existing arrangement is; distance from consumer unit to shower, 25m. Cabling 6mm², under floor in solemn space and in plaster for the last 1m. 32amp MCB on RCD protected circuit.
Our fuse box is an Merlin Gerin, (photos attached).

My questions are; (bearing in mind we are not changing the consumer unit and only wish to change the cabling and MCB for this one circuit),
Q1, would the Merlin Gerin consumer unit be able to be upgraded with a modern Schneider Acti9 45 amp MCB in place of the Multi9 MCB.
Q2, Are our current Multi9 MCBs a C-curve? I'm not sure if the writing on the current MCBs indicate the Curve type.
Q3, Would the Schneider replacement MCBs need to be a C-Curve or B-Curve type in whichever case?
Q4, Rather than a consumer unit upgrade, could we actually just update all the MCBs in the consumer unit this way?
Q4, Should we upgrade all the MCBs to RCBOs instead. (Assuming there is room in the consumer unit for such an upgrade as I understand they are quite large in comparison).

From my internet of things investigation... I gather that Merlin Gerin are no longer in manufacture and subsequently that the proper replacement for Multi9 would be Schneider Acti9. Would this be the correct information?

Any good advice appreciated for 3 dirty children and a smelly wife... I've always been a clean guy...

 

[Midwest]

Are you still intending moving out of this house soon? If so then forget fiddling about cobbling things together and leave it for the next homeowner. They may well get their own sparky to change things to how they want them to be. Probably RCBOs.

Didn't realise this thread was still going. I'd leave well alone as well. Let the next home owner rectify things, unless things are unsafe now.

 

[Iain Stewart]

Well according to the EICR, the Electrician recommended that the lighting be put on an RCD protected circuit. I assume that would be a good idea at any rate...

If we put our house on the market and in these times, it may not sell for a couple of years even though it's a good well maintained property.

In the earlier posts people have said the CU is of very high quality and more used in an industrial environment than in a domestic environment. Yes the board may not comply with today's standards but surely when this CU was made Merlin Gerin allowed for the scope to be broadened to suit any requirements especially as this CU is primarily intended for a commercial environment?

 

[Midwest]

Well according to the EICR, the Electrician recommended that the lighting be put on an RCD protected circuit. I assume that would be a good idea at any rate...

If we put our house on the market and in these times, it may not sell for a couple of years even though it's a good well maintained property.

In the earlier posts people have said the CU is of very high quality and more used in an industrial environment than in a domestic environment. Yes the board may not comply with today's standards but surely when this CU was made Merlin Gerin allowed for the scope to be broadened to suit any requirements especially as this CU is primarily intended for a commercial environment?

Really depends on your intentions on whether to move or not. Thousands of properties have lighting circuits not protected by an RCD. Whilst of course it would make things safer, this is only a recent requirement for new properties.

If your intention is to stay put, get the rectifications carried out. If you intend to move, I really wouldn't bother. Not reading back, but I don't recall the EICR saying anything was unsafe?

 

[Iain Stewart]

Really depends on your intentions on whether to move or not. Thousands of properties have lighting circuits not protected by an RCD. Whilst of course it would make things safer, this is only a recent requirement for new properties.

If your intention is to stay put, get the rectifications carried out. If you intend to move, I really wouldn't bother. Not reading back, but I don't recall the EICR saying anything was unsafe?

Yes the report was satisfactory. I was thinking that this would be the least expensive method of making the installation safe as per the Electricians recommendations for the short term...

 

[westward10]

You are intent on doing it no matter what advice we give. Be interesting to know how you will adapt the busbar which is not designed for modification.

 

[Iain Stewart]

You are intent on doing it no matter what advice we give. Be interesting to know how you will adapt the busbar which is not designed for modification.

I never said I was intent on doing it! That's your assumption but hey we are all allowed to think what we like... I will consider your advise thanks.

 

[Pete999]

I never said I was intent on doing it! That's your assumption but hey we are all allowed to think what we like... I will consider your advise thanks.

You have had a lot of advice, Westward is not known for flippant posts Mate

 

[Iain Stewart]

You have had a lot of advice, Westward is not known for flippant posts Mate
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You have had a lot of advice, Westward is not known for flippant posts Mate

Fine ok mate...
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Time to put this one to bed... Thanks again and all the best!

 

[davesparks]

Ok guys following your advice with sourcing used or new old stock and a chat with a retired Electrician, I have decided to have the CU converted to a double RCD unit. This is bearing in mind that the initial EICR recommended having the lighting put on an RCD circuit too.

We have found this RCCB on eBay, see photo, and have a photo of the CU with cover off. However, I have noticed that they look different despite the fact that the serial/product numbers on the RCCB's are the exact same. I cannot find another one like this and also there is a strange, non-switched, unit to the left of the RCCB with a L sticker on it. Is this a part of the RCCB or some other kind of device?

Thanks...

You can't convert these boards to dual RCD.

The busbar is factory fitted in the plastic casing and not accessible for future alterations. There is a gap in it where the RCD fits.
The live terminal block to the left of the RCD takes the live from the busbar to the bottom of the RCD, the RCD outgoing side connects directly to the second half of the busbar.
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Rather than faffing with trying to alter your existing CU a better option would be to swap the entire CU, a bit more expensive, but far better in the grand scheme of things, good luck

Swapping the CU will be cheaper than doing what is necessary to add rcd protection to all circuits on this one.
However a new CU will be much lower quality than the existing MG unit, even the new MG boards aren't as good as those ones.

 

[Strima]

I’d swap the RCD for a switch and source some RCBOs.

 

[DPG]

I’d swap the RCD for a switch and source some RCBOs.

I'd s leave the bloody thing alone.

 

[Iain Stewart]

Thank you Davesparks. An excellent explanation of why it can't be done.
I appreciate your input, very valued indeed.

Pete999
I will leave it as it is and leave the rewire and new CU to the possible new owner. Thanks for the good info.

STRIMA and DPG, you are driving me crazy...hahaha

Tell you guys what! Figure out between you what the best solution would be utilising the existing CU by using any means possible, new Busbars, RCBO's whatever, and I will pay for you to come and fix it for me!

Thanks once again...

 

[DPG]

No offence intended. I've had several pints so being a bit too vocal maybe. One of the guys on here would willingly offer their services I'm sure. Just be careful of Tel - he's a bit filthy. And davesparks can be a bit moody. But they are all good guys. Not being sexist there by the way - guys includes men and women to me. That's before sparky chick kicks off. Look at me - a bit merry and still punctuating like a God.

Mine' s a rum and coke. Ta.

 

[Iain Stewart]

Not being sexist there by the way - guys includes men and women to me. That's before sparky chick kicks off.

Me neither...

 

[davesparks]

My opinion is that the best thing would be to replace the mcbs with RCBO's.

If it was my house I'd be digging through our stores to find the RCBO's to do the job, I'm pretty sure I'd find everything needed in there somewhere.
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Tell you guys what! Figure out between you what the best solution would be utilising the existing CU by using any means possible, new Busbars, RCBO's whatever, and I will pay for you to come and fix it for me!

Well if you're paying for transport, accommodation and food I'll do it.

I like my steak rare and my liquor strong!