Using external wall cavity to carry 2.5mm T&E cable

[Grumps]

Hi I think the subject explains most of what I'm looking to do. I need to add a double socket and the best place for the cable is the wall cavity. The socket is on an exernal wall on the ground floor which has floorboards. The wall cavity is insulated but not with polystyrene balls. Apart from the various rules saying it's an undesirable situation, are there any tips to accomplish said task? Was going to drill at a downward angle into the cavity from where the socket will be, and hope to pick up the cable into a hole into the cavity under floorboard level. I was intending to have a bigger diameter hole under the floor and use a hook to pull the cable through, assuming it ever feeds into the right location! Could protect holes to avoid damaging cable when pulling through. Any other tips? Ta.

[nothanks]

You can make it easier to catch the cable by pushing a doubled tape measure into the hole so that is spreads out against the outer leaf.

[tabbypurr]

It can be a pain getting hold of the cable at the lower end.

[Roger Hayter]

You may need to use something like fencing partly hardened steel wire to force it through the edge of an insulation batt if you are unlucky. It may need derating for being insulated, an electrician will tell us if it is ok for a 32A ring.

[Tricky Dicky]

In my daughter's new build the meter tails run approx. 3m in the cavity from the external meter box to the CU. When the houses were being built the external walls were cavity insulated with foam sheets so I presume a channel was left to feed the cables through.

Richard