Shower and wiring help!

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Hello All. My electric shower has stopped working (10.5 kW). Had a look at the CU, MCB for the shower circuit is rated at 32A and the cable is 6mm. The cable run from the CU to the pull cord isolator is 6 meters max out of which 2 meters is in a plastic conduit behind plaster (in the bathroom) the rest is under the floor board and loft. I want to replace my shower 10.8 kW, upgrade cable to 10mm, upgrade MCB to 45A. The CU in place at the moment is a MK sentry 7 way, the main isolator is rated at 63A. The main fuse is sealed, not sure what the rating is but on the fuse carrier it reads 'AEI series 3-100'. My question is can I use a 45A MCB with a 63A main isolator or do i need to upgrade the main isolator to say 80A?

Many thanks

 

[PrenticeBoyofDerry]

If you consumer unit does not have RCD protection your new shower circuit must.
Whether it means that a new CU is needed or you can install a RCBO depends on the CU you have, and if you can purchase one for that type of unit.
The 63A main isolator may need upgrading, again depending on the total load that is being used in the consumer unit.
You must be aware that this type of work, is classed as notifiable work due to the location and also the adding of a new circuit.
//www.diynot.com/wiki/electrics:part_p