chasing into concrete screed floors - a risk to the neighbour's lights?

[laike]

i live in a 1960s built ex-local authority flat. the floors are concrete with approx 30mm of screed poured on top, brick walls. the existing cabling is all MICC which i'm considering ripping out, not because it doesn't work but because i'm looking to move some walls and chase new central heating pipework into the concrete floors. am pretty certain this is going to nick an MICC cable and the circuit will be screwed. not to mention it's not much more expensive to do a full rewire than to find someone who can repair MICC.

QUESTION:if i'm chasing into the screed to run my new cables, is there a risk that i could cut the neighbour's below me lighting cables? is there a chance their lights are running through my screed? (if not, how did they possibly run their lights to their bedroom as their ceiling / my floor is concrete?)

really frustrating job this, if there are any certified NICEIC sparks reading this who are keen to take it on, get in touch. location: dalston, london.

 

[Marty203]

Marty203 are you sure you are not getting mixed up with maisonettes as I could then understand if their downstairs lighting conduits came from their bedrooms above. Perhaps if you where a young lad at the time you may of only worked on those parts of a large job and not remembered or recalled the conduit arrangements for the bedroom lighting which should of been cast into the slab?

Im not that old that I cant remember, lol, the projects were high rise council flats, Hounslow and Feltham and a few in the north around Islington and The Barbicon in the east

 

[Mr Mark Sparks]

I agree. I get to see the work done by NICEIC sparks, and a lot of it is shoddy.
By the way, I work for an NICEIC firm, I do the inspection & testing, and Ive never met the NICEIC man.

Im QS for nic firm and we have annual visit
and have to jump through hoops

 

[SPARTYKUS]

Hello Tony

yes, it should be "nowt", a slight erroneous transcription from brain to screen.

I may be slightly lysdexic

 

[johnboy6083]

Im QS for nic firm and we have annual visit
and have to jump through hoops

im sure that for small firms, this is the case. Im sure that may outfits choose the jobs that they show their assessors.
I work for a very large M&E firm, with over 800 tradesmen on the books. I work out of a satellite office, where im one of 8 sparks. As you can tell, im not a fan of the current system of QS. Its not effective in a large firm, where nobody ever see's my work.

 

[Mr Mark Sparks]

im sure that for small firms, this is the case. Im sure that may outfits choose the jobs that they show their assessors.
I work for a very large M&E firm, with over 800 tradesmen on the books. I work out of a satellite office, where im one of 8 sparks. As you can tell, im not a fan of the current system of QS. Its not effective in a large firm, where nobody ever see's my work.

i thought we were a large firm with 140 employees m and e. a/c and security devisions ect but would agree that you tend to pick and choose work from the "better" guys to show them

 

[laike]

Question guys: this is a maisonette with 2 floors undergoing a rewire. How to wire the lights on the lower floor? Options are 1) battening and 2) chase screed above and drop through floor. Everyone seems to prefer option 1 but me! Why is it so hard, especially as we'll be chasing the screed to lay pipework for central heating?
Are there any regulations against running lighting cables in the screed above?

 

[Engineer54]

Question guys: this is a maisonette with 2 floors undergoing a rewire. How to wire the lights on the lower floor? Options are 1) battening and 2) chase screed above and drop through floor. Everyone seems to prefer option 1 but me! Why is it so hard, especially as we'll be chasing the screed to lay pipework for central heating?
Are there any regulations against running lighting cables in the screed above?

Seeing as you'd be running a cable installation from one installations equipotential zone into another installations equipotential zone, what do you think??

 

[Deleted member 72666]

Hello Tony

yes, it should be "nowt", a slight erroneous transcription from brain to screen.

I may be slightly lysdexic

Me too! I have sex daily..... I mean dyslexia!

 

[KAS1]

If this is a maisonette with 2 floors and he's wiring the lower floor lights from the upper floor how would he be running a cable installation from one installations equipotential zone into another installations equipotential zone, or am I missing something?

Seeing as you'd be running a cable installation from one installations equipotential zone into another installations equipotential zone, what do you think??

 

[laike]

i'm not an electrician, what's an equipotential zone! :tounge_smile:

so the only option is battening the ceiling then? crap!!!

 

[KAS1]

Is it a flat or maisonette? there is a difference IMO "in my flat (i live in a 2-story maisonette)"

 

[laike]

it's a 2 story, ex council, 1960s built flat. with brick walls, concrete floors, and MICC cabling (to be ripped out for the rewire).

see pics.



structural report

Visual Observations

• At first floor level, adjacent to the stair well is a small airing cupboard with a water tank. The floor in this area was lifted to reveal a soft grey material, which on first impression was thought to be a floor screed.

• With the aid of a chisel, the soft grey material was easily broken away to reveal a water pipe buried within it.

• The depth to the bottom of the copper pipe was approximately 30mm.

• Below was a further pipe.

• It is believed that the two pipes are the flow and return to the water tank located within the airing cupboard.

• The depth of the screed is therefore most likely approximately 50mm in depth.

• The ceiling of the ground floor reception room was also exposed in one location to reveal a smooth concrete surface, of different colouration and texture to the soft grey material observed within the airing cupboard.

Figure 1 – Exposed Screeded Slab Surface – Airing Cupboard

Conclusions/Recommendations

Based on our visual observations, it appears that the floor structure is of reinforced concrete construction. It was not possible to conclusively determine if the floor slab was of precast or in-situ construction. Based on the surface finish to the soffit area exposed, it would suggest that the floor slab is most likely of pre-cast concrete construction.

To the top surface of the concrete floor slab is quite clearly a screed of approximately 50mm in depth, which has services within it as was seen in the airing cupboard.

We understand that you wish to run further new services within the screed layer. We can confirm that this will not affect the structural performance of the concrete floor slab. However, it should be ensured that the screed is broken out carefully (not with an angle girder or similar) to ensure that the concrete surface of the floor slab is not damaged or cut into.

 

[Engineer54]

If this is a maisonette with 2 floors and he's wiring the lower floor lights from the upper floor how would he be running a cable installation from one installations equipotential zone into another installations equipotential zone, or am I missing something?

Yep, your right, and that's fine if it's a two storey maisonette and he's using the screed on the upper floor to run his cables in, for the lower floor. Not too sure what he's going to do for the upper floor lighting though?? ..lol!!

My only worry would be, that the surveyor mentions that the floor slabs are of the precast type. Making penetrations in precast concrete slabs, need to be undertaken with caution, especially if they are of the pre tensioned variety!!

 

[laike]

Not too sure what he's going to do for the upper floor lighting though?? ..lol!!

it's the top floor maisonette, upper floor lighting run above plasterboard ceilings (no concrete)

My only worry would be, that the surveyor mentions that the floor slabs are of the precast type. Making penetrations in precast concrete slabs, need to be undertaken with caution, especially if they are of the pre tensioned variety!!

he said he was unable to determine, and IMO he was not the sharpest tool in the shed. are these photos any help in determining the construction?



those are the pipes that punch through the floor to go to the gravity water tank. notice there is a brick laid in the middle of the concrete! WTF?

that looks poured-in to me, not precast. any opinions?

 

[Engineer54]

From the photo's you posted, it certainly looks like an in-situ poured slab, rather than precast !!