On 29/01/2018 14:48, dennis@home wrote:
On 29/01/2018 14:38, jim wrote:
"dennis@home" Wrote in message:
On 29/01/2018 13:05, jim wrote:

Does retrofitting mcbs into an older wylex "fuse wire" consumer
unit need notification?

The plug in ones don't have the same breaking capacity as te fuse wire
so you may need to check they are OK.

The plug in MCBs (if that's what you are using) can't cope with as much
fault current as the more common MCBs or fuse wire.

The first bit of that is true, but the second bit is questionable...

Modern MCBs can typically safely interrupt fault currents of up to 6kA.
The plug in wylex style MCBs only 3kA.

The BS3036 re-wireable fuse carriers had typically one of three ratings
S1A, S2A, and S4A. These could interrupt 1, 2, and 4kA respectively.

The common type that most will recognise:

http://wiki.diyfaq.org.uk/index.php/...fuse_225-6.jpg

were I believe a S2A rated carrier - so swapping one for a 3kA rated MCB
is unlikely to be an issue in most cases unless the pre-existing fuses
were not actually suited to the installation anyway.

If however you are comparing the plug in MCB with a cartridge fuse
carrier, then there may well be a reduction in the maximum rupture
capacity.


--
Cheers,

John.

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