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Old February 5th 18, 03:51 PM posted to uk.d-i-y
Fredxx[_3_] Fredxx[_3_] is offline
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Default Adding RCBOs to Wyler Split Load CU

On 05/02/2018 14:18, wrote:
On Monday, February 5, 2018 at 1:28:04 PM UTC, John Rumm wrote:
On 05/02/2018 10:33,
Hi All,

I have a Wyler 12 way split load CU (NHrS12SL).

For various reasons, I will be having a qualified sparky do the
work, but wanted to check my options...

Currently our CU has most of the power circuits on the RCD side,
and 3 lighting circuits (which could maybe be reduced to 2
(combine the 2 downstairs circuits into 1 (it’s not a mansion).
And the immersion is also on the non RCD side.

I am thinking it is time to give at least the lighting circuits
RCD protection, but would like to avoid the cost of a new Box
(which would allow 2 RCDs).

Any particular reason for wanting to change?

The electrican who has been making ammendments to one of the existing
lighting circuits saus that he HAS to put it on RCD in order for it
to be regs compliant.

Interesting, this is an existing circuit and I thought an 'extension' or
'spur' was exempt from having to conform to the new regs.

Not that its a bad thing to move the circuit such it becomes RCD protected.

I wondereed about doing all the lighting circuits while I was about
it. Wylex "say" that all circuts run under plaster should be RCD
protected (well, they would wouldn't they), and if possible I'd
rather not have all the lights go out together, so a bunch of RCBOs
on the non RCD side seems attractive.

Rules now dictate that lighting must be split into at least two separate
RCD protected circuits, so if one fails the other can still provide some

Wylex are correct for 'new' installations, where a cable is buried less
than 50mm from a surface. Surface wiring does not need a RCD, nor wiring
that is sufficiently mechanically protected, nor armoured cable.