TT and RCD

[Thomo39]

Evening all, I'm just after some clarification on what set up is best/required by the regs..
TT system , cable comes into the house into the cut out , tails into the meter and then out of the meter into the DB.
Currently a small board with RCBOS doing lights and power and then a 40amp MCB feeding a RCBO in an enclosure just below the DB which supplies a SWA that feeds an external garage DB with a 30ma RCD main switch.
At the moment when something trips in the garage it trips the RCBO in the house as there is no discrimination between the RCD and the RCBO, whats the best set needed here?
Cheers

 

[flameport]

100mA time delayed RCD and a suitable size fuse for the SWA, 30mA RCD or 30mA RCBOs in the garage. If using RCBOs, they will need to either be double pole or single pole with switched neutral.

a 40amp MCB feeding a RCBO in an enclosure just below the DB

A rather strange arrangement - is there any RCD upstream of that MCB?
A photo of the entire lot (meter, incoming supply, consumer unit and the surrounding cabling) would be helpful.

 

[Thomo39]

100mA time delayed RCD and a suitable size fuse for the SWA, 30mA RCD or 30mA RCBOs in the garage. If using RCBOs, they will need to either be double pole or single pole with switched neutral.


A rather strange arrangement - is there any RCD upstream of that MCB?
A photo of the entire lot (meter, incoming supply, consumer unit and the surrounding cabling) would be helpful.

 

[flameport]

Using what's there, the RCBO in the separate box could just as well be put in the main consumer unit and the cable extended to that (or jointed in the smaller box and a blank fitted in the front), the other MCB isn't needed and there is no protection for the cable between that MCB and the RCBO.
That won't solve the issue of the RCBO tripping due to a fault in the garage, but the RCD in the garage could be removed and replaced with a switch instead as it's not needed with an RCBO for the whole circuit.

The consumer unit appears to have sagged in the centre with a gap above some of the RCBOs, suggesting it has overheated at some point. Further investigation required there.
The screw on the right side is not the correct one for the lid.
The RCBOs appear to be C type, which is an odd choice for a domestic installation.
SWA cable needs fixing to the wall.

 

[Thomo39]

Using what's there, the RCBO in the separate box could just as well be put in the main consumer unit and the cable extended to that (or jointed in the smaller box and a blank fitted in the front), the other MCB isn't needed and there is no protection for the cable between that MCB and the RCBO.
That won't solve the issue of the RCBO tripping due to a fault in the garage, but the RCD in the garage could be removed and replaced with a switch instead as it's not needed with an RCBO for the whole circuit.

The consumer unit appears to have sagged in the centre with a gap above some of the RCBOs, suggesting it has overheated at some point. Further investigation required there.
The screw on the right side is not the correct one for the lid.
The RCBOs appear to be C type, which is an odd choice for a domestic installation.
SWA cable needs fixing to the wall.

Cheers mate.
I'm putting a new DB in tomorrow so I'm going to take that SWA in to the new DB on its own RCBO.
It was more about wether i needed a 100ma rcd between the tails and the main switch however the idea of ditching the rcd main switch in the garage is a good one

 

[flameport]

It was more about whether i needed a 100ma rcd between the tails and the main switch

Not normally, although the tails must be double insulated and also supported properly both outside and inside the consumer unit and where they enter the consumer unit to ensure they can't be damaged and short onto the metal casing.