Connecting different sized cabling

[mancduff]

I need to use 2.5mm cabling for my powershower thats the max i can fit to the terminal inside wall mounted casing, problem is the only cable i could spur off is 6mm cabling serving one socket (thats never used) which in turn is feeding another socket that runs the washing machine the cabling to this socket is 2.5mm (wasn't here when spark did this).
Could i run 6mm to the fcu and then from the fcu 2.5 to the shower, these two sockets are on an MCB which is 20amps with backup RCD and the FCU will have 3 amp fuse in it, the junction box i used was 30amp one.

Thanks

 

[Lectrician]

Why 2.5 to the shower?? It could be smaller for a power-shower.

As the circuit is protected by a 20amp MCB, 2.5 would be fine to use from the socket to the FCU. Not conventional, but ok.

 

[jeepmadmike]

fit a fused spur, spured off the socket and wire it in 1.0mm?

 

[mancduff]

Thanks for your reply
I have already cut into the 6mm cable and attached it to a junction box (socket is downstairs cable is upstairs and was easier to spur off)
so if i run 6mm to the fcu are you saying it shouldn't be a problem running 2.5 or below from the FCU to powershower, only i don't want to end up burning the house down, i'd never here the end of it.