a KMF switch (isolator) problems please help !

[jaybhill]

Hi I am unsure on the regs with this I have a 100a main fuse but need to run tails outside
in armoured cable into loft of extension I know that I need a kmf switch but I'm struggling to find a small 100 amp one (not enough room for the big wylex ones) can I use a Switch Fuse Moulded Single Pole & Neutral, with 80A HRC Fuse or does it need to be equal to the main service fuse ?

Thank you.

 

[sjm]

Your overcurrent protection only needs to be enough to cover your supply requirements, size of cable etc.
How about a double pole mcb in 2 module enclosure? Gives overcurrent and isolation.

 

[Spudnik]

Indeed, the smallest switchfuse i have seen is the KMF 80A.

To be honest, if you are using 25mm SWA, you really would want to try and terminate it in anything but the larger ones.