thanks you all again
i will install new as per existing,just to confirm there is the fused spur behind the dishwasher(picture above) and also a isolation switch on the wall would I still require isolation at the CPU can i isolate via isolation on wall gonna check everything before commencing with voltage pen anyway.
You can Isolate at the isolation switch, providing it is local to where you are working and cannot be accidentally or intentional re-energised, whilst you work on the electrics, you must use an approved voltage indicator the prove the circuit is dead and safe to work on, although voltage pens have there usages, they are non-contact and you will require a two pole instrument to be sure you are safe.
With regards to unswitched or switched FCU. You can use either but I would personally use an unswitched one. This would prevent the appliance be switched off accidentally when you push the appliance back in place.
Sometimes the hoses or even the back of the appliance can come in contact with the switch and do this, when space is restrictive.
PS. Ignore the nutter, he's getting giddy because Santa's bringing him a neon screwdriver to play with!
It is important when powering down a circuit, you correctly identify the circuit or part of the circuit you are isolating, then prove it is dead using approved test instruments, for this purpose a two probe instrument must be used. Even if you open the main isolator at the board, that does not mean you assume the installation is completely dead! You only live once, make it as long as you can!
