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
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
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
Web said:
A cable’s design life is based on the cable running at maximum load all day every day for 25 years. At maximum load, the cable conductor will be at its maximum temperature, normally either 70℃ or 90℃, depending on the cable’s grade of insulation and it’s BS specification.
If the cable is not fully loaded all of the time then it can be expected to exceed its design life. For example, if the cable is loaded for 8 hours in a day, its life expectancy could be in excess of 40 years.
Then a list of things that could effect life.
So in short, we don't know.... Obviously loading will be reasonably light in most domestic applications. We are using Or for what it's worth. If the cable is not fully loaded all of the time then it can be expected to exceed its design life. For example, if the cable is loaded for 8 hours in a day, its life expectancy could be in excess of 40 years.
Then a list of things that could effect life.
Obviously if it where 25years it would likely need doing while we where still there, and which point conduit would be extremely important to me.
But it re-enforces the issue, that it's likely these cables will be replaced at some point in the future, both in our house and others, so it's not a stupid question.
Daniel
Alucidnation said:
Planning on what might happen in 25 years time to an electrical installation is a bit odd tbh.
An awful lot can and will change in that time.
Granted things change and I don't have a globe, but if anything surely that support using conduit for big drops where within the time we are in the house we might want to re-spec whats going to the light switch? On the flip side the 13amp plug has been around 70 years, as an evolution of the round pin series before it, and while we might totally change our electricity usage we also might not.An awful lot can and will change in that time.
My parents built there house in 1988 and 31 years later its already well past 25years on the same wiring and in the 60's they might get well get to 50 years living in the same house. I am now 31 have just bought what I hope and expect to me mine and my partners family home, so again the 'design brief' where practical is a 50 years life expectancy. As said, the house is 115 years old and there is no reason to presume it wont do another.
Its not like I am talking about going mad, to swap a bit of capping strip for some conduit, in some for the large drops in the big rooms.
Round might be pushing it for clearance, but the '25mm oval' at 28x11x0.8 seems perfect.....? Might raise it with my electrician, he will love me.
Daniel
Pheo said:
It’ll be a lot easier to cap them I suspect in terms of filling the chase.
If you are really sure you’re going to go in again then I guess use conduit. But if you’re doing that how likely you’re going to be redecorating anyway so running in some new wires wouldn’t be that disruptive
Really hard to know isn't it. If you are really sure you’re going to go in again then I guess use conduit. But if you’re doing that how likely you’re going to be redecorating anyway so running in some new wires wouldn’t be that disruptive
Hard to know what might change or how long these cables will last. Obviously the room will be redecorated again but I'm hoping having replaced the linning paper future redecorating would just be a repaint.
Obviously there is an afternoons work in fitting the conduit but it shouldn't be much/any harder to plaster over should it?
Daniel
Well, plasterer is due today (i'm at work) so its all about the buried in a renovating lime and cement mix for all eternity.
I did buy some 25mm oval, it was much easier to get a pair of twin and earth down than the electrician suggested as while you have to get the kinks out is did just slide in in one hit. I could get the top end up behind the plaster moulding away from any risk of plaster getting down the tube, and in several cases I managed to get it though the ceiling up behind the first floor skirting. Obviously at the box end you could bring it down to the round grommet and while you wont be able to pull the cable past there without changing the box it does save 7 1/2 foot of chase all the way down the wall.
The downside is however in a couple of places the way its been run with sockets on the other side of the wall, there is a continuous loop of cable and I didnt have time to cut it on the far side, pull through, and feed back, one of the power cables also goes though mid-wall into the room with the cu. The two lighting chases would need 2x25mm to get them down and the case wasnt wide enough and I didnt have time to widen it. Two of them I changed and then when adding the speaker cables the electrician changed it back to capping because that can fit 2x2.5 1x.15 and a Cat6 where the conduit can't.
Obviously I know the cables will likely last 50 years, by which time I will be 82, and if they do another ten from there its unlikely to be my problem, and someone can always chase it out again, but its also just seems a shame that everything seems to be about cutting costs as long as its ok for now, nobody does a rolls-royce job even if thats what you ask them for. The original spec-sheet requesting the work say 'conduit to be used where practical, to allow cables to be replaced' but along with clipping cables in the loft thats just been forgotten in the interest of speed and cost.
Heyho, either I am mad, or the world cant be arsed to do it nicely. Roll on f
king up the eu and polluting out planet with single us plastics.
Daniel
I did buy some 25mm oval, it was much easier to get a pair of twin and earth down than the electrician suggested as while you have to get the kinks out is did just slide in in one hit. I could get the top end up behind the plaster moulding away from any risk of plaster getting down the tube, and in several cases I managed to get it though the ceiling up behind the first floor skirting. Obviously at the box end you could bring it down to the round grommet and while you wont be able to pull the cable past there without changing the box it does save 7 1/2 foot of chase all the way down the wall.
The downside is however in a couple of places the way its been run with sockets on the other side of the wall, there is a continuous loop of cable and I didnt have time to cut it on the far side, pull through, and feed back, one of the power cables also goes though mid-wall into the room with the cu. The two lighting chases would need 2x25mm to get them down and the case wasnt wide enough and I didnt have time to widen it. Two of them I changed and then when adding the speaker cables the electrician changed it back to capping because that can fit 2x2.5 1x.15 and a Cat6 where the conduit can't.
Obviously I know the cables will likely last 50 years, by which time I will be 82, and if they do another ten from there its unlikely to be my problem, and someone can always chase it out again, but its also just seems a shame that everything seems to be about cutting costs as long as its ok for now, nobody does a rolls-royce job even if thats what you ask them for. The original spec-sheet requesting the work say 'conduit to be used where practical, to allow cables to be replaced' but along with clipping cables in the loft thats just been forgotten in the interest of speed and cost.
Heyho, either I am mad, or the world cant be arsed to do it nicely. Roll on f
king up the eu and polluting out planet with single us plastics.Daniel
Yeah, its a right mixed bag. Annoying but not the end of the world.
My last house was a 1938 council build, solidly built and a cracking house, but years of low budget work, badly dot & dabbed, patched this, re-done that, and I largely carried on the same. Replace what needed and keep the rest.
Slight difference here for me in a way is that this is a largely original and reasonably un-molested 115 year old Edwardian build, bar being split into two semis and re-wired in 1965 and the bay windows being replaced 30years ago. So while it is a very long way from a conservation project I do feel some obligation not to bugger it up too much during my tenanture. The first owners did 65years between further and son, the last owners 35 years, and we plan another long spell.
Daniel
My last house was a 1938 council build, solidly built and a cracking house, but years of low budget work, badly dot & dabbed, patched this, re-done that, and I largely carried on the same. Replace what needed and keep the rest.
Slight difference here for me in a way is that this is a largely original and reasonably un-molested 115 year old Edwardian build, bar being split into two semis and re-wired in 1965 and the bay windows being replaced 30years ago. So while it is a very long way from a conservation project I do feel some obligation not to bugger it up too much during my tenanture. The first owners did 65years between further and son, the last owners 35 years, and we plan another long spell.
Daniel
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