3. A large number of switch-mode power supplies: household PCs,
router, NAS Etc, which all added up. Cured by replacing all the 32 amp
MCBs with RCBOs to give each ring it's own 30ma leakage budget.


Seconded. my old CU was a split load job, with 4 MCBs on a 30mA RCD
feeding a cooker, two ring mains and an immersion. The other half of the
CU was two MCBs feeding two lighting circuits.

Whenever I started two PCs or more at the same time, that would trip the
RCD. The trouble was that 30mA leakage current budget was spread across
four circuits.

I then got the CU changed for one that had RCBOs only and i split
several circuits up into smaller circuits and added new circuits. This I
went from 6 to 13 circuits, all on RCBO's

I also added high integrity as well, so the smoke dets, CO dets and
intruder alarm are on their own RCBO, the outside sockets are on their
own RCBO and the outside lights are on their own RCBO. That way anything
happening outside does not affect the inside.

The boiler is also on its own RCBO so reducing the risk of the house
freezing over if a different circuit develops a fault.

I've not had a single trip since.

although RCBOs are more expensive, its worth every penny from the
hassle/inconvenience/ease of fault finding point of view.