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.

 

[Phillcbr400]

Not had time too read all the above posts,
But my house has a concrete screed floor downstairs. So essentially what you have is everything goes to the first floor void and drops down or goes up.
The central heating was surface mounted in mini trunking. I have chased this into the walls. Then into an inspection box. From here it's buried using plastic pipes wrapped in insulation within conduit. Then another inspection box at each radiator bottom for the legs.
Hope this helps

 

[Engineer54]

=Engineer54;765902]If a conduit installation, the conduit runs would be within the slab, installed just after the steel re-bar fixers, with the conduits tied to the re-bar. Never seen a conduit installation run on top of the slab, as for anything else, it would be out of it's installations equipotential zone, if located as you state, especially if were talking for a block of flats situation...

]Thats how we do it here and have done since day one, but in the 60's in the UK the steel conduit was laid on the top of the slab, the holes for the lights were formed when the slab was poured and there was a 100mm soft screed laid over the slab which covered the conduits, heating pipes etc, I dont know how they do it now, you may have never seen it but thats the way it was done all over the country and if you could bend the stuff and you could earn a fortune as most sparks were paid per flat for first fix

I'll say it again, i've never seen conduit installed this way, not in all the years i've been in the industry. It makes no sense whatsoever cost wise, or electrically!! I can only think that your talking about precast concrete slabs?? But even then, installing a metallic electrical distribution system that is outside of it's equipotential zone, again makes no sense!! And in the 60's it's unlikely that any CPC's would have been part of the wiring of that conduit system either!!

 

[laike]

structural engineer comes out to the flat.

'where's the screed?'
'right there'
'have you got a chisel?'
'here'
*chisels a massive chunk out*
'yes that's screed, chase away. can you pay me £540 now?'

 

[Engineer54]

More to the point, ....what did the Structural Engineer say about your intentions to knock down walls in the apartment?? That's far more important than any screed you have over your slab floors!!! lol!!

 

[laike]

he said it's fine, but the council surveyor already told me that. was a complete waste of money, basically. i guess if the building does collapse a la that dhaka primark factory at least i've got a letter saying it's not my fault - though i'd probably be crushed in the process.

 

[Marty203]

I'll say it again, i've never seen conduit installed this way, not in all the years i've been in the industry. It makes no sense whatsoever cost wise, or electrically!! I can only think that your talking about precast concrete slabs?? But even then, installing a metallic electrical distribution system that is outside of it's equipotential zone, again makes no sense!! And in the 60's it's unlikely that any CPC's would have been part of the wiring of that conduit system either!!

I understand that you may not of seen it and you find it hard to believe, but high rise flats were wired in metalic conduit laid directly to the floor slab which was not pre cast, the lighing for the flat below was installed on the slab of the flat above, we did not install earthing conductors in the conduits as the conduit was the earthing conductor, the earth connection at the lighing point, switch or power outlet was via a cable connected to the earth lug in the box (which we had to install whilst installing the box) a soft sand screed was laid on the slab to produce the floor, this screed covered all of the conduits, I am not a liar or making this up, what I find hard to believe is the fact that you seem to want to argue when I thought the point of the forum was there to help each other, however, enough said, I know what work I carried out and how it was done on many high rise site in London, I hope there are some old buggers like me who carried out the same type of work.

 

[Engineer54]

I understand that you may not of seen it and you find it hard to believe, but high rise flats were wired in metalic conduit laid directly to the floor slab which was not pre cast, the lighing for the flat below was installed on the slab of the flat above, we did not install earthing conductors in the conduits as the conduit was the earthing conductor, the earth connection at the lighing point, switch or power outlet was via a cable connected to the earth lug in the box (which we had to install whilst installing the box) a soft sand screed was laid on the slab to produce the floor, this screed covered all of the conduits, I am not a liar or making this up, what I find hard to believe is the fact that you seem to want to argue when I thought the point of the forum was there to help each other, however, enough said, I know what work I carried out and how it was done on many high rise site in London, I hope there are some old buggers like me who carried out the same type of work.

I am one of those old buggers, but as i say, only seen conventional methods of installing conduits into slabs. ...lol!!

 

[KAS1]

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?

 

[driverman]

Many years ago I can remember wiring some brand new flats in the Midlands area. We used Volex pre-wired PVC conduit which was buried in the above flat floor screed. The Volex pvc conduit fed the downstairs lighting circuits. So I would suggest be very careful, take nothing for granted. Any one remember above product? Is it still about?

 

[lauriehurman]

Life in Australia is obviously completely different,

what I find hard to believe is the fact that you seem to want to argue when I thought the point of the forum was there to help each other,

 

[SPARTYKUS]

Forums here to argue too! If we all agreed there'd be owt to discuss!

 

[Knobhead]

Shouldn't that be nowt?

 

[GLENNSPARK]

Shouldn't that be nowt?

getting to be a point this as well in here just lately Tony..
as in nowt meaningful to discuss...

 

[Knobhead]

That’s you’re speciality, isn’t it?

 

[GLENNSPARK]

That’s you’re speciality, isn’t it?

and whats this supposed to mean...?
come on man...explain yourself...