This is likely to cause conflicting opinions, but hey… 
We’ve got an extension built in the side of our 1960’s house that was built around 1999. They had botched fire cable through the roof for the outside lights to an fcb in the kitchen. This has now failed and I need to replace. There is a new t+e run from an rcbo in the cu for lights/cameras that is in the roof of the extension - I need to run a cable up from the hole in the wall to a junction box outside to connect the circuit. The cable run is essentially running up the house external wall in the roof void of the extension and out of the external wall about 1m above (over the roof apex). The cavity is filled with blown wool/fibre.
I know bridging is of normal concern, but it is irrelevant in this case; would it be safe to run 1.5mm pond flex directly up the cavity, or t+e 1.5mm in corrugated trunking?
I am aware this isn’t ideal, but literally no other way!
We’ve got an extension built in the side of our 1960’s house that was built around 1999. They had botched fire cable through the roof for the outside lights to an fcb in the kitchen. This has now failed and I need to replace. There is a new t+e run from an rcbo in the cu for lights/cameras that is in the roof of the extension - I need to run a cable up from the hole in the wall to a junction box outside to connect the circuit. The cable run is essentially running up the house external wall in the roof void of the extension and out of the external wall about 1m above (over the roof apex). The cavity is filled with blown wool/fibre.
I know bridging is of normal concern, but it is irrelevant in this case; would it be safe to run 1.5mm pond flex directly up the cavity, or t+e 1.5mm in corrugated trunking?
I am aware this isn’t ideal, but literally no other way!
