Re-wire 80's lighting circuit or not?

[plugwash]

Have just bought a Victorian first floor 2 bed conversion. Am having it re-wired but the lighting circuit is difficult to access as there are people living in the flat above whom I'm sure wouldn't let me pull their carpets and floorboards up to access the wiring. Also there are nice ornate ceiling roses and coving which I'd like to retain which means cutting a chase up the walls and across the lath and plaster ceiling would be pretty difficult too.
The lights all work and have the white sheathed red/black twin and earth cable.
I'm thinking about putting a new loop cable under the floor and up in to the switches and re-using the switch wire to connect to the ceiling roses.
Any comments gratefully received.

So what you are proposing is to convert the wiring from "loop at rose" to loop at switch by abandoning the existing circuit cables, running new circuit cables via the switches and changing the role of the existing switch drops from carrying permanent live+switched live+earth to carrying switched live+neutral+earth.

There is nothing electrically wrong with with this, the big question is what are you trying to achieve by doing it. You won't be able to say the circuit has been fully rewired because it won't have been.

If the existing lighting circuit is both electrically OK and fit for purpose then as others have said you may as well just leave the thing in it's entirety rather than putting a load of effort into partially rewriting it.

On the other hand if you are planning to add a load of wall lighting (which will require neutrals at the switches) or if there are faults in the exsting circuit cables that can't easilly be fixed while the switch drops are OK then what you propose may make sense.

 

[amuiphoto]

So what you are proposing is to convert the wiring from "loop at rose" to loop at switch by abandoning the existing circuit cables, running new circuit cables via the switches and changing the role of the existing switch drops from carrying permanent live+switched live+earth to carrying switched live+neutral+earth.

Yes, this exactly what I was thinking of doing. However having taken on board the very useful advice offered here I can see that the existing wiring needs to be properly tested before any conclusions are drawn.

Also what appears to be the case is that 1980's white T&E cabling doesn't necessarily need to be replaced if it still functions correctly.

 

[phatboy]

Also what appears to be the case is that 1980's white T&E cabling doesn't necessarily need to be replaced if it still functions correctly.

Its the same stuff that we use now, except that the colours are different. You just need a sticker by the CU to say that there are 2 colour conventions if you add new cabling.

 

[OwainDIYer]

Also what appears to be the case is that 1980's white T&E cabling doesn't necessarily need to be replaced if it still functions correctly.

I'm still installing it