Discuss Inspection Report, Electric Shower, Merlin Gerin and Schneider MCBs in the UK Electrical Forum area at ElectriciansForums.net

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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...
 

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Schneider C60H RCBO's will fit that board. Merlin Gerin is now Schneider so only the colours and name changed on their switch gear.

Do not try and get the iC60H range to fit as they will not, only the C60H.

This way you will only need to install a new busbar rather than replace the whole board. I'd go full RCBO.

TBH that board is a very good make and I would be very reluctant to rip it out, unless required all your devices only need to be B type unless you have LED units with high inrush currents and the manufacturers recommend C type or if you have a decent sized welder in the garage.
 
Hi - just my opinion, but why not just replace like for like if you’re moving on?
For the upgrade it sounds like you would need a new cable from the CU to the uprated local isolator and then the new shower. But rather than mess about with the old Consumer Unit I’d probably put in a separate little board - Schneider do a 50A one (as you’ve mentioned them).
 
The odd thing that jumps out at me in the pictures is a relatively new 100a DP isolator which only has the live tail connected through it with the neutral being straight through a SP block. Why would anyone do that ?
 
The odd thing that jumps out at me in the pictures is a relatively new 100a DP isolator which only has the live tail connected through it with the neutral being straight through a SP block. Why would anyone do that ?

It's odd to fit a DP isolator when they are only connecting the line, but not unusual for a DNO to fit a single pole isolator in the line only.
Self connect meters with a built in isolator are single pole, and I've seen single pole isolators fitted in seperate enclosures occasionally.
 
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