Running cables in insulated floor void

[i_DaveJ]

I am planning a rewire of our 1960s bungalow, for power sockets running cables under the floor. There is a 200mm floor void over a concrete oversite. I plan to insulate under the floor, 100mm under joist and 100mm between joists. I know cable is best not run within the insulation. If I leave/cut, say, 50x50mm channels at the top of the insulation would it be ok to lay the cables in these? There's a variety of enabling work to do before an electrician is required (insulation laying, taking up floor boards etc.) but wanted to get an understanding of what would be best so that I can prepare and organise. If a channel within the insulation would be ok, how deep under the floorboards would be acceptable i.e. as suggested, 50mm or could it be less?

 

[westward10]

If it is a bungalow run it all in the loft space.

 

[i_DaveJ]

If it is a bungalow run it all in the loft space.

Thanks westward,
That's an option. I guess as the person picking up the tab I was trying to minimise the length of cable and chasing to saves on costs - this would require another 70+m of cable and definitely require two ring mains instead of one. Is the rationale that the loft is more easily accessible for installation and later alterations? If the flooring is coming up anyway, would benefit of running in the loft space be less? It would require tricky drops on the outside wall where access to the eaves is tight (but not impossible). Running cables in the loft could avoid the insulation issue, except where it runs down through it but then conduit could be used there. So yeah, what's the rationale?

 

[westward10]

Bungalows are the easiest of dwellings to work on as you have a loft space to cover all areas and avoids concealing cables in floor voids which often become difficult to access if required due to floor coverings. The extra cost for cable is pretty negligible. Most electricians are used to tight loft spaces.

 

[Wilko]

Hi - if you are doing renovations then cables should travel in the loft and then down chases in the internal walls. If you do put cables in the insulated underfloor area they may well need to be up-sized and so perhaps not as cheap anyway. Just my 20p .