Consumer Units with RCBOs

Screwfix have a BG 12 module CU with 6 RCBOs on offer for £69.99. At t hat price it is a steal so I am thinking of getting 2, one for the main hou se CU and I know it is overkill but one for the garage. I do want discrimin ation in the garage with 2 lighting circuits one for the main garage/worksh op and one for the separated mancave, likewise 2 ring mains and all the out side lights will also be run off the garage CU.
The question is connecting the garage CU to the house CU? In the 17th editi on wiki article the CU arrangement for a fully RCBO populated CU shows an M CB being used for the garage using SWA. In my case that will not be possibl e as the cable between CUs will be T&E with approx. 2m run in a wall chase. Is there any reason why the garage circuit cannot be protected by an RCBO at the house CU even though there will be further RCBOs for the separate ga rage/Mancave circuits?
Richard
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On Wednesday, 15 May 2019 17:15:35 UTC+1, Tricky Dicky wrote:

Yes, discrimination.
AFAICS no time-delay / 100mA RCDs are available as RCBOs, so you'd need to allow for a 2-module time-delay RCD and an MCB for the garage - if they're available in BG.
Also someone will hopefully clarify whether 100mA time-delay is acceptable for protecting buried cable.
Owain
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On 15/05/2019 17:30, snipped-for-privacy@gowanhill.com wrote:

It should be 30mA non time delayed.
Or make it a deviation from the regs and don't RCD it.
--
Adam

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Just checked the stock at Screwfix and none of the stores have any availabl e so it's back to the drawing board. There is a similar one available at £99.99 with mini RCBOs but it gets a poor review from an electrician.
Richard
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On 15/05/2019 17:15, Tricky Dicky wrote:

sadly out of stock around here (well, the 6 nearest - I gave up at that point)
--
Robin
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On 15/05/2019 17:15, Tricky Dicky wrote:

If it uses the same sort of RCBO it will probably trip if there is a fault on one of the garage circuits.
You need one that trips slower and/or higher leakage to avoid this.
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On 15/05/2019 17:15, Tricky Dicky wrote:

Yup, you will lose discrimination.
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On Wednesday, 15 May 2019 17:15:35 UTC+1, Tricky Dicky wrote:

If you don't mind an RCD board (with the option of some high integrity RCBO s) this is better than a steal
https://www.switchgeardirect.co.uk/product-category/clearance/
16 way dual RCD, your choice of MCBs, £50 inc.
Owain
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snipped-for-privacy@gowanhill.com scribeth thus

Have TLC electrical not got any, we had a couple from them a while ago?
https://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/BG_Consumer _Units/index.html
--
Tony Sayer


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On Thursday, 16 May 2019 11:43:15 UTC+1, tony sayer wrote:

Their 16 way only comes with 12 MCBs, their choice not yours, and is £ 68 + delivery + VAT.
Owain
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On 16/05/2019 08:48, snipped-for-privacy@gowanhill.com wrote:

Do you know what (if any) other brands fit Havell's boards? I was told they have pulled out of the UK market (so replacement MCBs etc might be hard to source).
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Robin
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Apologies for resurecting this thread, but one final question. If I cannot have RCBOs at both ends of the garage supply, if I go for RCBOs in the gara ge CU and stick with am MCB in the main CU, does that MCB need to be outsid e of any RCD protected group or can it be RCD protected. There is a possibi lity that my garage supply cable can be re-routed under the floor and withi n cupboards or voids where none of it would require burial in a wall rather than the original plan which was to take it through the loft where at leas t 2m would have to be buried in a wall. I will not know how easy this will be until I lift a few boards and see.
Richard
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On Mon, 27 May 2019 01:47:44 -0700 (PDT), Tricky Dicky

Yes, No
Any difference between N and L current will trip an RCBO or RCD AB
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On 27/05/2019 09:47, Tricky Dicky wrote:

My (limited) understanding is that it wouldnt NEED to be RCD protected but there is no requirement that it is *not* so protected.
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On 27/05/2019 09:47, Tricky Dicky wrote:

The MCB should have NO RCD protection. Only the garage end should be RCD protected.
Did you know that if you bury the cable more than 5cm from the finished surface on the 2m run then it would not need RCD protection?
--
Adam

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On 27/05/2019 12:13, ARW wrote:

Or mechanical protection applied. steel conduit should require no extra protection.
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On 27/05/2019 12:13, ARW wrote:

I thought surface wiring was exempt too on the basis you're unlikely to poke a nail through a visible cable? Or is that only SWA?
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