Electrical conduit in walls.
Discussion
These days it seems more common to use 'capping' to cover previously loose wires prior to plastering over, however previously people have used steel and then plastic conduit before plastering. This prevents you replacing the cable by drawing through new with re-chasing it.
Is this down to cost/speed? Thinner plaster? If re-wiring a house with older thick plaster could you still use proper conduit? To allow future changes and or re-wire to be done more easily. If there much benefit?
Daniel
Is this down to cost/speed? Thinner plaster? If re-wiring a house with older thick plaster could you still use proper conduit? To allow future changes and or re-wire to be done more easily. If there much benefit?
Daniel
You could use 20mm conduit and single cables, I remember removing "slip tube" type conduit (around 7\16th id) when I was an apprentice spark (too many years ago) which had rubber sheathed cables (perished usually).
I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
IET forum indicates this may be because the expectation was housed would need to be required far more frequently than is actually the case, with PVC having a rather long lifespan. Therefore the time isn’t worth it
That being said my sparky seems to think he can draw cables through behind dot and dabbed plasterboard anyway, and I’m not sure you actually even need to cap the cables anymore due to dot and dab.
That being said my sparky seems to think he can draw cables through behind dot and dabbed plasterboard anyway, and I’m not sure you actually even need to cap the cables anymore due to dot and dab.
L1OFF said:
You could use 20mm conduit and single cables, I remember removing "slip tube" type conduit (around 7\16th id) when I was an apprentice spark (too many years ago) which had rubber sheathed cables (perished usually).
I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
Why MICC out of interest?I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
There's not even any requirements in the regs to use capping. but it is good practice. If the cable is in a chase and in the safe zones you can just clip it in place, fill the chase in with bonding and then plaster over.
Conduit is a nice idea as it allows easy replacement of cables and possibly extra ones to be added retrospectively provided there's room. Costly though so I doubt you'd see it on any new builds.
Conduit is a nice idea as it allows easy replacement of cables and possibly extra ones to be added retrospectively provided there's room. Costly though so I doubt you'd see it on any new builds.
I imagine most people figure that they will not need to rewire in their ownership, similarly tradesmen wont care how easy it will be in the future so why do it any other way but the most cost effective?
I recently added some new sockets chased in sold walls and used conduit as it seemed logical to me and barely any difference in cost really.
I recently added some new sockets chased in sold walls and used conduit as it seemed logical to me and barely any difference in cost really.
C0ffin D0dger said:
There's not even any requirements in the regs to use capping. but it is good practice. If the cable is in a chase and in the safe zones you can just clip it in place, fill the chase in with bonding and then plaster over.
Conduit is a nice idea as it allows easy replacement of cables and possibly extra ones to be added retrospectively provided there's room. Costly though so I doubt you'd see it on any new builds.
In a new build the cable is just dropped behind the plasterboard so it doesn't matter through? Conduit is a nice idea as it allows easy replacement of cables and possibly extra ones to be added retrospectively provided there's room. Costly though so I doubt you'd see it on any new builds.
Ok, about as expected then. Make sense about protecting from the trowel! Point taken about dot and dab too.
The average plaster depth is mostly 25mm but never less then 20mm that I've measured. Currently most of the first fit is in and recently capped off. It's all PVC going in obviously which will last however long? The house is 115 years old and what's coming out is early stranded PVC from the 60's, skirting mounted sockets and no earth on the lighting.
Where it exists we're reusing the original Edwardian thin wall steel conduit or the 20mm pvc oval used in the 60's but where it's not we're chasing it out, about six 6ft chases for sockets and two 4ft chases for light switches per room and it's just seems a crying shame not to be laying conduit.
Just been quoted £800 by the plasterer to patch all chases and £1200 from the decoratior to redo the linning paper and paint the lounge alone, which as sort of out the cost of the chases into perspective!
Hoping to be here 50years, which the PVC should last for, but it still makes you wonder, for the sake of swapping it over now.
Daniel
The average plaster depth is mostly 25mm but never less then 20mm that I've measured. Currently most of the first fit is in and recently capped off. It's all PVC going in obviously which will last however long? The house is 115 years old and what's coming out is early stranded PVC from the 60's, skirting mounted sockets and no earth on the lighting.
Where it exists we're reusing the original Edwardian thin wall steel conduit or the 20mm pvc oval used in the 60's but where it's not we're chasing it out, about six 6ft chases for sockets and two 4ft chases for light switches per room and it's just seems a crying shame not to be laying conduit.
Just been quoted £800 by the plasterer to patch all chases and £1200 from the decoratior to redo the linning paper and paint the lounge alone, which as sort of out the cost of the chases into perspective!
Hoping to be here 50years, which the PVC should last for, but it still makes you wonder, for the sake of swapping it over now.
Daniel
dhutch said:
Where it exists we're reusing the original Edwardian thin wall steel conduit or the 20mm pvc oval used in the 60's but where it's not we're chasing it out, about six 6ft chases for sockets and two 4ft chases for light switches per room and it's just seems a crying shame not to be laying conduit.
Would an Edwardian property have original conduit? I wouldn't have though it would have been wired when built. Or are they repurposed gas lighting lines?Flibble said:
L1OFF said:
You could use 20mm conduit and single cables, I remember removing "slip tube" type conduit (around 7\16th id) when I was an apprentice spark (too many years ago) which had rubber sheathed cables (perished usually).
I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
Why MICC out of interest?I've started to rewire my listed cottage in MICC (Pyro as used to be called), not cheap.
Early cables in houses were rubber covered in lead and single cables were rubber covered in cotton these were installed in pin grip conduit. When rewiring old houses the pin grip was dismantled above the drops down to switches the conduit was reused to install the new pvc cables. Saved re chasing walls. Also some internal walls were hollow and had lathe and plaster construction so cables could be hidden behind.
Flibble said:
Would an Edwardian property have original conduit? I wouldn't have though it would have been wired when built. Or are they repurposed gas lighting lines?
I've looked into it, and it appears likely it was, just. Planning was put in 1902 and the local electric light station opened in 1896 and extended into our area at the turn of the century. There is very a light and wall switch in most rooms, no more, lead sheathed paper insulated cables. Conduit is plastered in to the original lime with no evidence it's be retro fitted. No trace of any gas lighting. House was a large property in its time, now split into two, built be a successful Liverpool merchant. was8v said:
I think you need to find a different plasterer. And decorator.
PVC plastered over will outlast your lifetime so why complicate things?
We've got multiple quotes for both, and they are coming out about the same. £200/day for the plaster, £185/day for the decorator, which appears to be about the going rate. There must be 50 holes to patch in lath and plaster walls, and maybe 20 chases downstairs, plus a few ceiling repairs. The room being decorated is the main room, floor is 8.5 x 5m, ceilings must be pushing 9-10 ft, original plaster moulding and full height fire place and 10" skirting boards. Condition is mixed and obviously stripping the whole room of paper and making walls and ceiling good afterwards will take work, as will the woodwork. I must say why I first saw the price having never paid for this sort of work I half fell off my chair, but I have done enough patching plasterboard and stripping paper to know its not going to take them an afternoon.PVC plastered over will outlast your lifetime so why complicate things?
Anyway
Back the the question of why? Because if a re-wire has a 50-60 year life span which is what the previous installation did, there is a decent chance the next person will have to go through the same as me, and for their sake and the house sake, I just wondered if maybe for the big room we should swap the capping out for some oval conduit, half a days work, so they dont have chase it out all over again.
I realise most will think I am mad, but if £150 spend now saves someone else in 50 years time three times and a load of faff hacking at a nice house, personally I see that as something to think about.
Daniel
Edited by dhutch on Thursday 10th January 13:51
Alucidnation said:
dhutch said:
Because [if] a re-wire has a 50-60 year life span
Who told you that?This is primarily due more to spec change as requirements have changed with than cable degradation as it would be if vir, we have no earth on the lighting circuit, very few sockets which are all singles at skirting level, single switched hall lights etc. so obviously it may well last longer.
What is the current suggested life expectancy of solid core pvc t&e cable?
Daniel
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