Burying 2.5mm ring circuit cable under concrete floor in flexi conduit

[Vortigern]

What is your view about such an installation technique? Asked to finish extension wiring and the installer has snaked wire all over the floor in white flexi. They intend to put an island in and this could easily lead to damaged cables. The other wiring for lights etc. is abysmal like a massive spaghetti nightmare. I have declined the job but just wondered what your thoughts were on burying cables in concrete floor, would you do it?

 

[Rockingit]

Not a preferred option but allowable and I've had to do it myself in the past (minus the spaghetti!)

 

[goasis]

Have done, in order to get cables to a kitchen island for example

 

[buzzlightyear]

yes if there is no other way ,i have done it ,with a tins like the great escape ,me tom dick and harry .lol. put in conduit .

 

[Dustydazzler]

No problem putting cables in the screed concrete floor , I always put rigid pvc conduit in clipped in place before the screed goes down

 

[Mike Johnson]

I used to always map the route of the cables/conduits in concrete on a drawing and put it in the CU taped to the door with the EICR, smoke alarm reports now as well, theres posh.

 

[Dustydazzler]

isnt all that paper a potential fire risk

 

[Mike Johnson]

No it's inside an Asbestos envelope.

 

[Rockingit]

No it's inside an Asbestos envelope.

I wondered where I'd left my pulling pants

 

[buzzlightyear]

I have declined the job but just wondered what your thoughts were on burying cables in concrete floor

why did you do that ,me 10 bit coins and a pallet of Heinz spagitti hoops to sort it out .

 

[davesparks]

I wouldn't take on a job like that unless I was desperate for the work (so if they haven't opened the theatres by January I might consider such a job)

Flexi conduit, assuming it is the usual bog-roll thin stuff, isn't strong enough in my opinion, it could easily be crushed when the concrete or screed is laid on it, or even by the other trades stamping all over it beforehand.
Rigid PVC conduit routed so that it is out of walkways as far as possible would be my minimum, I normally use steel conduit on the rare occasions that I do such work.

 

[Vortigern]

When looking at the job I thought what a waste of cable, he could have gone to each socket horizontally and save two thirds of the cable used. Plus avoid the problem of if there is a fault, you do not have to dig up the kitchen floor! Personally I would avoid burying cables in the floor where ever possible. Maybe in some conduit so the cable could be pulled out in fault conditions.

 

[Strima]

I've used PVC rigid in the past as a bare minimum. Most flexi stuff is paper thin and you'd be better off using McDonalds straws...

 

[Rockingit]

I've used PVC rigid in the past as a bare minimum. Most flexi stuff is paper thin and you'd be better off using McDonalds straws...

Also a whole lot easier to thread cables down!!

 

[Mike Johnson]

The problem with McDonalds straws it they usually come with the dreaded milk shake, after sucking through one of those my eyes hurt.

 

[davesparks]

When looking at the job I thought what a waste of cable, he could have gone to each socket horizontally and save two thirds of the cable used. Plus avoid the problem of if there is a fault, you do not have to dig up the kitchen floor! Personally I would avoid burying cables in the floor where ever possible. Maybe in some conduit so the cable could be pulled out in fault conditions.

Conversely I would rather go through the floor than have cables buried in the wall horizontally.
I was taught that cables should always run vertically, most people know that cables run vertically but not horizontally or in the corners. Whilst the safe zones are ok in theory nobody but electricians know about them.

 

[ChrisElectrical88]

Love a good 2x2 galv trunking in the floor.
If that’s overkill then it’s galv conduit

 

[Leesparkykent]

I wouldn't take on a job like that unless I was desperate for the work (so if they haven't opened the theatres by January I might consider such a job)

Flexi conduit, assuming it is the usual bog-roll thin stuff, isn't strong enough in my opinion, it could easily be crushed when the concrete or screed is laid on it, or even by the other trades stamping all over it beforehand.
Rigid PVC conduit routed so that it is out of walkways as far as possible would be my minimum, I normally use steel conduit on the rare occasions that I do such work.

You not got much on @davesparks? I have a house in Leatherhead thats being converted to 3 assisted living apartments with an extension. 1st fix needs starting in a few weeks, Basically will be 3 small flats with a staff area....Your more then welcome to take it on if your interested?

 

[freddo]

Rigid plastic is also the minimum for me, usually do galv though. Just done some to a shop island counter and some floor boxes, 25mm for power, 32mm for data.

 

[Vortigern]

I am quite happy to go horizontally but certainly would eschew underfloor cables in concrete. I would say it is far easier to replace cable in a wall than concrete floor. At 450mm height I think there is a far lower chance of fixing something into a cable than a vertical rising cable above an accessory. There is also the fact that we are supposed to install with a view to saving resources, such as cable and take the best route to achieve this, which would be horizontal.

 

[lozarus]

I mean ultimately AFAIK it's out of zones, so why not (in reg terms)? I've used the paper thin stuff personally in my house for one job - but I've laid the concrete over myself, and it's quite obvious that it's happened (and noted accordingly at DB) so I can't really comment on what other trades may do. Ultimately the risk of someone drilling into the floor in the future is still there - but you can't eliminate every risk - and it's a much lower risk than being scratted across the wall at every angle and getting caught by a picture book. I've also seen it don't plenty of times in schools with 20mm PVC conduit. Again, the concrete itself provides plenty of protection from external influences, as long as the route is logical.

 

[davesparks]

You not got much on @davesparks? I have a house in Leatherhead thats being converted to 3 assisted living apartments with an extension. 1st fix needs starting in a few weeks, Basically will be 3 small flats with a staff area....Your more then welcome to take it on if your interested?

Thankyou, I'll send you a PM

 

[BruvDunk]

Galv me thinks
Always nice to dig out the conduit bender.....