Cable run under concrete slab using flexicon

[shoaib]

Hi,

In a domestic new wire; before the concrete floor slab has been laid down; i am proposing to run the cabling for the ring mains.

I have been advised to use flexicon steel flexible conduit for mechanical protection and im using 2.5 T+E.

Question:

A) Do i run the conduits and leave them running up a chase in the wall at each point a socket will be at and then pull the T+E through after the concrete has been poured.

Or

B) Should i pull through the T+E at the same time as laying down the conduit before the slab goes in.


Reason im asking is that on a test run; it is pretty difficult pulling through the flexicon when it is not in a rigid secure position and moreover: the conduits flexibility is impaired when it contains the cable meaning that i cant run it smoothly around the corners and up the walls the way i want.

Many thanks in advance for your help

Shoaib

 

[Deleted member 26818]

I take it this flexicon is similar to Kopex?
If so, I would at least feed a draw wire through, as the Kopex can end up in some very odd shapes after the concrete is poured.

 

[johnboy6083]

If I were you I would install rigid conduit, plastic or steel. As theothers have said, leave a draw in, but you might struggle pulling twin through 20mm, especially copex

 

[bugsy]

I would deffo use solid conduit , as mentioned during thr pouring of the concrete the kopex / flexico could be pushed into tight bends , which ever method you elect to use you will need to put in draw wires ( and if you not on site all the time tape the ends to the conduit ) Ive idiots pull them out on more than 1 occaision

 

[Engineer54]

Why would you need Mechanical protection when installing conduits in the floor slab???

All modern projects use high grade PVC conduits in slab work. That flexible stuff can be a real nightmare to wire, as it kinks and contorts during the concrete pour. Another reason they don't use metallic forms of conduit these days, is due to possible future corrosion problems. Even the PVC coated flexible metallic conduits can be damaged during installation and pour operations.

To be honest, i wouldn't even consider them for this type of installation. ....There's a very high possibility that some those flexible conduit runs won't be wire-able, So be very careful if you DO use them....


EDIT...

Even rigid PVC conduit needs to be tied down, wet concrete can and will lift conduits if not securely fixed to the re-bar etc. ....Yes bring the conduits up at the proposed outlet positions (again securely fix to wall) slightly longer than you need, cut to size when fixing back boxes...