Black Sheep, many thanks for the clarity.
May I ask the following 3 and hopefully final questions
1. My current (LJU) master socket has a flush fitting face plate (with metal back box). I take it that the BT engineer will replace it with a flush fitting NTE5 face place.
2. Will the engineer replace the existing back box, or just re-use it. Presumably if the existing back box to the 'old' LJU master socket is left in situ the existing screw holes on it will line up with the new NTE5 face plate.
2. What 'flavour' of NTE5 is most likely to be fitted. My previous house had a NTE5A. But I understand that there is now a 'new' NTE5C.
Many thanks again for everybody's kind help.
Cheers
Please bear in mind my reply is a generalisation, and not tailored to yours or anybody's, specific situation.
To answer your 3 questions at once (as they kind of all link together) ............... the engineer
should replace your existing LJU for the latest NTE5C and also install a MK4 SSFP (filtered front-plate) as well,
if required.
I would humbly suggest that 99% of the time, the existing
sunken back-box will accommodate the newer faceplate without issue. If it doesn't, we will NOT replace the back-box as I'm afraid OR's policy is, and always has been, to only install
flush-fitting fixtures such as cable, boxes and sockets.
The terminology has to be right here ......... flush-fitting in
this instance means we would fix a new plastic back-box direct onto the plaster, as opposed to a sunken back-box that the electricians will have chased out and installed when the house was built.
Of the other 1% of occasions the new plate wont connect to the back-box, then it's a case of nattering with the customer and working out what is best for them. More often than not it may be a case of fitting a blanking plate to the older sunken back-box, and extending the cables into a position for the newer flush-fitting back-box .... which would be either above, below or to the side of the original box .... ensuring no wires are actually on show.
I hope this makes sense .... it does it my napper.