- Reaction score
- 2,862
The upstream RCD is probably seeing a lot more leakage than individual downstream RCBOs, because it's protecting the whole installation. It's likely to be closer to it's tripping threshold, so a small amount of leakage on a downstream circuit might push it over the edge, while failing to trip the downstream RCBO.So, here's a thing. Not conventional for a domestic, and not cheap, but an adjustable RCD could in theory be set for bang-on 300mS @ 30mA / 40mS @ 150mA and be compliant, basically relying on the downstream devices being inherently faster (which we all know they typically are, by a significant margin).
So the above might work, for some faults, might not.