I have seen someone on Youtube when doing a socket chased out the backbox as usual and then the area for the cable to come up from the floor to the backbox.

However the person then used pipe looked like black pvc going from the floor to the backbox hole. He did 2 one for the incoming cable and the outgoing on the ring. This was the set in plaster to hold the pipe / conduit.

I have never seen this before as normally you put the cable up the wall and plaster over it. Is this ok as it seems a good idea to replace cable if any issues maybe better for Ethernet cables, but will the pipe be ok behind the plaster no expansion or contraction and will electrical cable be ok in PVC pipe?

Thanks for any comments.