extending consumer units

I am building an extension to my house and will be adding a new ring main for internal, ring main for garden (sheds, etc.), lighting internal and lighting external. I wish to connect these to a new consumer unit as my 6-way unit is full. My question is this - can I take a feed from an MCB in my current unit (I will need to disconnect the boiler) to the new unit (boiler will be moved to this), or will I have to connect new tails from the in-feed of the existing unit to the in-feed of the new unit? If the latter, how do I do this safely with the mains fuses in place (if I remove them the tamper seals are broken)? replacing the 6-way unit for a 10 or 12-way unit is not really possible due to space limitations (the new consumer unit will be fitted to the opposite wall in the understairs cupboard).

Thanks

there are lots of views on this, try a search on new consumers unit, moving consumers unit

Mark, one way of doing this would be to buy an Enclosure that does not have a main switch isolator, but does come with a busbar to install MCB's.

Then you can put a 50A MCB in your existing consumer unit and use this as the feed to the new enclosure.

From the new enclosure you can then have the other circuits running off to the points in question.

Something a bit classier than Contactum

Thanks for the advice guys - much appreciated

Would 6mm T+E be sufficient or will I need to use 10mm as the feed to the new unit?

6mmsq is rated for 40A so if you are protecting the secondary board with a 50A MCB then you would need 10mmsq.