There won't be many RCBOs with a 100mA trip rating because that's stipulated for fire protection, rather than human safety.

However, Proteus do manufacture a 63A rated Type-A RCBO here in the UK.

CEF are the usual suppliers for Proteus trips, but other professional electrical outlets may order them if you ask specifically.
This isn't the sort of item you'd expect to source through a retail chain such as Toolstation (Travis Perkins Group), Screwfix and B&Q (Kingfisher Group).

Depending on the required cable length and the method of burial in the wall, I would expect the required mains cable size to be 10mm² or 16mm²

For current capacity above 63A you'd need to use a separate RCD (Type-A) and an MCB selected according to your cable size.

The RCD would need to be able to carry at least the same current as the MCB, and 125A would be fine.

The RCD and MCB will be 3-phase of course.
An inverter requiring that much current wouldn't be permitted by the DNO on a single-phase supply.

The other major manufacturer of such high-current RCDs and RCBOs is Chint.

They manufacture in China.
Their products are available here in UK,
or at reduced price by ordering direct from the Chint Electrical store on the AliExpress platform.

Delivery from China is typically 8-10 days at the moment.

Exactly @transparent , this type of RCBOs are not easily available. We are only considering a 8k inverter and it is only available from a couple of shops. And I did not find many brands. 

There are other ways to meet regulations. For example, to make sure all the cables are surface mounted and inside ducting. An electrician can advise on what may work in each case. Essentially that would enable use of double or triple pole MCBs that are very cheap (and commonly available for much higher Amps). 

My 8kw inverter is single phase and is only expected to export 5kw. The rest of the capacity may be for consumption. 

And before advising anyone to move a circuit from single phase to triple phase, I would need to understand the costs involved. If they are lucky to find anyone willing to put a ceiling on all the costs, that is great.

Otherwise, they need to be ready for the whole journey. @transparent may be able to expand on what this would typically involves. 

Posted by: @batpred

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Exactly @transparent , this type of RCBOs are not easily available.

It's the requirement to have 100mA earth-leakage tripping which makes your request more difficult to satisfy.
There are plenty of bi-directional Type-A RCBOs at 40A+ if the usual 30mA trip was acceptable.

I stopped looking once I'd find two products from reputable manufacturers with whom I've actually been in direct contact.
I wasn't anticipating that you'd use my recommendations as being indicative of the state of the market.

Posted by: @batpred

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There are other ways to meet regulations. For example, to make sure all the cables are surface mounted and inside ducting.

Surface-mounted cables will have a higher current rating than those within ducting due to their ability to release heat into the surrounding air.

There are several online cable-size calculators which allow the input of such parameters, such as this one by TLC-Direct.

Posted by: @batpred

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... Essentially that would enable use of double or triple pole MCBs that are very cheap (and commonly available for much higher Amps). 

Sorry, I don't follow that argument.

Double-pole MCBs are available for DIN-rail mounting in a consumer unit up to 125A,
But you'd still need a separate RCD to obtain any earth-leakage protection.

3-pole MCBs are for 3-phase supplies of course.

Posted by: @batpred

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And before advising anyone to move a circuit from single phase to triple phase, I would need to understand the costs involved.

I've just commented about that here on a topic about a Storage Battery problem.

Posted by: @transparent

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Posted by: @batpred

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Exactly @transparent , this type of RCBOs are not easily available.

It's the requirement to have 100mA earth-leakage tripping which makes your request more difficult to satisfy.
There are plenty of bi-directional Type-A RCBOs at 40A+ if the usual 30mA trip was acceptable.

I stopped looking once I'd find two products from reputable manufacturers with whom I've actually been in direct contact.
I wasn't anticipating that you'd use my recommendations as being indicative of the state of the market.

I do not understand the reason for the confusion.

I did not see more than a couple of 100ma bi directional RCBOs in the UK market, and of low amps. And as I mentioned, the grid power is very dirty in my area. So the Solis requires the ma to be higher than 100ma. 

In essence, they are not easily available. 

My advice is for anyone to consider alternatives that can meet the regulations. Another that electricians mentioned is to use armoured cable. This is more expensive than normal cable but it may provide predictability for the project. This may be of significant value to many. 

Posted by: @transparent

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Posted by: @batpred

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And before advising anyone to move a circuit from single phase to triple phase, I would need to understand the costs involved.

I've just commented about that here on a topic about a Storage Battery problem.

You seem to have included the wrong link, I could not find any figures. Hopefully your estimate is not close to what I was given - £3200 to install the battery and inverter? 

When I said "costs", I mean what the customer has to pay.

It's the correct link @batpred and here's the relevant text:

The only costs involved with the DNO upgrading a dwelling to 3-phase are those charged by your own electrician to divide the household circuits across the phases.

It's impossible to estimate that unless the present arrangement of consumer unit(s) and circuits is known.

Your estimate of £3200 for an electrician to install a battery and inverter depends on what is required to run cabling back to the consumer unit.
That's specific to the dwelling and can't be assessed here on an open forum without detailed knowledge of the property.

Posted by: @batpred

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And as I mentioned, the grid power is very dirty in my area. So the Solis requires the ma to be higher than 100ma. 

I don't follow that logic, but I can make two useful observations:

a: there shouldn't be any correlation between higher-frequency components being present on the 50Hz mains supply and whatever filters are incorporated into an inverter.

Those inbuilt filters may well result in a small amount of current leakage to ground, but the leakage current is the same irrespective of the quality of the mains sinusoidal waveform.

b: It is usually the case that higher-frequency noise is imposed onto the 50Hz mains supply by AC/DC switching electronics, such as found in the inverter.
In other words, the inverter is more likely to be the culprit, not the device being adversely affected.

In rare instances transient spikes are sufficiently large that they can cause degradation of insulation within a device,
or arcing within electronics.

There are transient suppressors which can remove such high frequency spikes and harmonics.
They are very often found in medical apparatus, for obvious reasons!

Since I have a number of (different types of) inverters, I've installed transient suppressor filters in reverse on their mains supplies.

That means I'm removing spikes which might be created within the inverter electronics, to prevent them propagating through the consumer unit to other household circuits.

The above photo was taken whilst that particular Consumer Unit was still being assembled.

The M4 terminals on those filters were fitted with tamper-resistant insulated caps before the remainder of the trips were installed onto the DIN rail.

Posted by: @batpred

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I did not see more than a couple of 100ma bi directional RCBOs in the UK market, and of low amps.

Quite possibly...

... and I've identified two more above, and provided the URLs so you can check their specifications.

Let me add yet another couple of brands to this growing list of RCBOs with 100mA leakage-current rating:

Geya is another Chinese-based manufacturer, and also well known to me.

The above listing can be found here on AliExpress, and you can choose from three alternatives for the earth-leakage trip current.

Geya also make DC MCBs, which can be used between a battery and an inverter, for example.
They are technically competent, and provide good customer service.

They don't advertise their complete range on AliExpress.
If you can't find what you want, click the button to send a Message to Seller and ask them (in English).

Next, there's this particularly cheap RCBO badged 'Live'' and available from the UK-based online reseller Electrical 4 Less.

I'm not finding it particularly difficult to identify where these RCBOs are available from.

But they're not 'consumer devices', and you'd normally expect your electrician to get them for you through his trade outlets.

Posted by: @transparent

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It's the correct link @batpred ...

The only costs involved with the DNO upgrading a dwelling to 3-phase are those charged by your own electrician to divide the household circuits across the phases.

Ok, but it would be helpful to get a figure. Perhaps assuming a standard arrangement of consumer unit(s) and circuits that a terraced house has?

Also I assume the dno is not responsible for making the areas where the new cable goes good.. so the cost to the consumer is more?

I am curious though about how electricity prices compare between 3 phase and single . Perhaps a new topic? 

Posted by: @transparent

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Posted by: @batpred

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And as I mentioned, the grid power is very dirty in my area. So the Solis requires the ma to be higher than 100ma. 

I don't follow that logic, ...

My dno's feed has a dirty neutral. Based on what Solis support said, when the inverter discharges that to earth, it causes triggering of rcbos.

When my installation finishes and I confirm the power in  the g99, I will notify these issues to the dno. Hopefully they will fix it. 

Posted by: @batpred

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I assume the dno is not responsible for making the areas where the new cable goes good

The following diagram is taken from the Meter Operator's Code of Practice guidance (MOCoPA)

When a dwelling is upgraded to 3-phase, your Energy Supplier coordinates with your DNO.

The devices on the blue and green sections of the diagram are changed together.

It has been the case in the past that some Energy Suppliers make a charge to install a 3ph Smart Meter.
However, if the work is being done based on a technical requirement from your DNO, then it's a safety issue, for which you shouldn't pay of course!

If your Supplier still tries to levy a charge under these circumstances, then telephone a rival supplier.
Tell them you'll move your account to them if they provide a 3ph meter.

That's a persuasive argument,
which you can then take back to your existing Supplier and tell them they're about to lose a customer!

Posted by: @batpred

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I am curious though about how electricity prices compare between 3 phase and single

The cost per kWh remains the same.
There isn't a different Tariff for householders with 3-phase domestic supplies.

3-phase Electricity Smart Meters operate under Vector Sum.

If your house is exporting to the grid on one phase, and importing on the other two, you are only charged for the difference between the phases.

Posted by: @jamespa

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Posted by: @transparent

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In your case @jamespa the Changeover Switch in a separate enclosure would also provide that functionality via a Centre-Off position.

That would make sense; the 2 off mcbs would need to go in the same enclosure so the challenge might be to find the right kit of parts!  A quick search didn't turn up any din mounted 4 pole 100A changeover switches with centre off other than an unbranded Chinese one.  Hopefully one exists!

I appreciate the challenge @jamespa ... 

This thread includes various suggestions. Geya have them, but I believe do not supply CUs. One option that at some point I considered was to use an ATS (of the type used in conjunction with a generator and an inverter) - just aiming to use the manual override. I think that, additionally to chinese brands, I found Schneider and Hager. But using an ATS could add questions so I managed to keep it as plan B. 

There will no problem in @jamespa getting a generic steel enclosure with an integral DIN rail
and putting whatever Transfer Switches and MCBs he needs into them

The enclosure doesn't have to sold as a "Consumer Unit",
nor is there any need to put <brand name> trips into <brand name> enclosures.

Posted by: @jamespa

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A quick search didn't turn up any din mounted 4 pole 100A changeover switches with centre off other than an unbranded Chinese one.

The Transfer switch doesn't need to have 100A capacity.

If the total of all loads on the main house CU is (say) 45A, then using a MTS (Manual Transfer Switch) rated at 63A is perfectly adequate.
Just supply its 'grid input' connection from a 63A MCB in the CU between the MTS and the meter.

If you were to fit an MTS rated at 100A, then the cabling would also have to be capable of carrying 100A, and would probably be 25mm².
That's expensive stuff!

Limit the current to 63A, and your electrician might be able to use 16mm² cable, depending on distance, proximity to other cables, and how it's routed.

There's a free cable-size calculator on the TLC Direct site.

A 'centre off' MTS may not literally have a centre-off position for a lever.

It could have two interlocked levers, only one of which can be up (on) at a time.

or perhaps a rotary switch like this:

I'm happy to help if you want guidance on which Chinese manufacturers are more reputable, or to
interpret specifications written in Chinglish.

@transparent thanks

Posted by: @transparent

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The Transfer switch doesn't need to have 100A capacity.

The main fuse is 80A, I was told to upgrade from 60A before getting an ashp.  In retrospect I don't know why.  However, given that this is rhe case it seems to me the transfer switch has to be rated at at least 80A as does everything else downstream until MCBs are reached.  Of course I could put in  63A MCB immediately prior, but its getting a bit silly tge number of components.