Main Consumer unit MCB for Garage Consumer unit

[Mark 9002]

House is 1992 build Timber Framed. Main House CU is an old Wylex that had Fused Wire type Fuses, but have been changed out for Wylex MCBs at some point. The Garage is fed from this through a 20A MCB to tghe Garage CU ( old )Fused type also. ) My intention is to have both replaced with New RCBO type CU's. The Garage has one Lighting Circuit 6A MCB and two 16A MCB Radials. One Radial feeds two Double Sockets, That don't have any heavy consumers except for a Tumbler Dryer). The Other Radial supplies Oil Boiler and one Double socket that just has a Freezer Plugged in .My Question is

I want all circuits to be on RCBO's. Because the Freezer is in the Garage is it Possible for the feed to the Garage from Main CU to remain on a normal MCB as the Garage circuits would all be on their own RCBOs anyway. My thought is that this would give the Freezer some redundancy, because anything in the Garage that would make an RCBO trip on the Main CU in the house would also cause the Freezer to loose Supply .
Hope I've got this across. Any thoughts on this pls . It would be nice to have some Idea before I start looking for Electrician to do the work.
Thanks

 

[pete01]

is it Possible for the feed to the Garage from Main CU to remain on a normal MCB

Yes its the best way, but you probably need to use swa cable...probably

 

[Mark 9002]

Thanks for that. It actually 2 core SWA to the garage CU. 10mm I think

 

[Murdochcat]

Better still add a dedicated FCU for the freezer and that can be on a MCB

 

[ericmark]

As a new install, the supply to the garage would need to be with a cable, or cable location, where RCD protection is not required. But not so sure of rules with an existing installation? I note my central heating is not RCD protected and that was only 18 months ago, and I have a compliance certificate.

In my case, a supply taken from the inverters UPS output, which powers 2 x double RCD sockets for freezers, and the central heating, the cable is SWA. No consumer unit used, just FCU and RCD socket outlets, I would have thought your garage could be the same?

 

[chivers67]

Thanks for that. It actually 2 core SWA to the garage CU. 10mm I think

Is the Protective core being used for an Earth? Should be ok, some would say it should still be RCD protected or at least a time delay version. As long as the Earth loop impedance is low enough for the protective device for it it should be alright.

 

[Mark 9002]

To answer a couple of questions
It's not a new install unless the regs say that replacing is a new install
The protective core of the SWA is being used to earth. It runs under the house ( not buried ) and into the garage which is built onto the end of the house.