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Fredxx[_3_] Fredxx[_3_] is offline
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Default Consumer Units with RCBOs

On 27/05/2019 15:04, John Rumm wrote:
On 27/05/2019 13:40, Fredxx wrote:
On 27/05/2019 12:13, ARW wrote:
On 27/05/2019 09:47, Tricky Dicky wrote:
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 garage CU and stick with am MCB in the main CU, does
that MCB need to be outside of any RCD protected group or can it be
RCD protected. There is a possibility that my garage supply cable
can be re-routed under the floor and within 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 least 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.

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?


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


Indeed.

Or is that only SWA?


No, that applies to T&E as well. (and surface wiring in trunking would
also be ok for the same reason)


That was my understanding but not sure if it changed under 18th ed. Of
course a decorator might just sink the cable into the plaster and cover
with PVC channelling!