My advice is to forget about the T&E and just install a conduit with draw wire in the wall so that the SWA can be pulled in to it when it is installed thus avoiding any joints in a new circuit.
Th conduit would need to come out if the wall below the CU to allow fitting of the gland but could be covered with a blank plate for now.
Thanks davesparks (and thanks Archy Styrigg). Draw wire sounds like a good approach.
If I understand correctly I would need to leave a pull wire through an appropriately sized hole in the Stud Wall foot plate. The hole would need to be large enough to accept the diameter of the SWA.
There are no noggins below the Consumer Unit, so perhaps no need for a temporary conduit, if this is what you meant.
The only problem is that the Noggin at the height of the consumer unit. As well as supporting the consumer unit, it helps to support the weight of the cables exiting the back of the CU before dropping down. But then it also narrows and impedes the route into the back of the CU.
I think regardless of any conduit it will make it difficult for the electrician to pull in the SWA.
However I imagine that it might be possible with the main fuse switched off to temporarily unscrew the whole of the CU and pull it away enough from the wall to enable a cable to be pulled up and worked through the back. Just guessing. Perhaps electricians have other standard tricks to overcome this particular
issue.
Tricky, but it would be great to have the whole run in SWA and installed by an electrician. Let me off the hook? Food for thought.
I investigated a socket today feeding the boiler. It was 1.5 T/E. But could not find a corresponding FCU anywhere to correspond.
From the cellar I could see two 2.5 T/E main loop cables disappearing up into masonry but on the wall a single 1.5 T/E. It had been doing my head in for a few days.
I brought in a wire detector to try and trace. Was not sure if the detector would be any good through masonry (very cheap unit I bought years ago).
The 2.5 T/E were buried JUST beneath the surface of a separate of a adjoining wall and were picked up by the detector. No question of Permitted Zones here!
Chiseled out the 2.5 T/E in its plastic sheathing up to a standard 30Amp junction box, where it output 1.5 T/E round the corner.
The tough plastic junction box even had metallic plates plastered in front. But the hidden cables dropping down, hidden just beneath the surface, just begging for a nail was.. well Shocking!
Was this ok practice in the 80's when the original conversion I believe took place?
This is the third Hidden electrical outlet I have found! But the worst so far.
Thanks to all.