Cables in Trunking

[Nickfromwales]

4 hours ago, Onoff said:

Any route between floors is still a potential fire /smoke route for sources other than the cu don't forget.

A point a little too specific to apply to a UK residential dwelling imo. 

By the time fire and smoke sought out and breached such transits, the smoke detection system will have been wailing for a long time.

We ( British BRegs ) favour the early alert aka smoke / heat alarms rather than structural integrity it seems, and apart from fire resistant light fittings I doubt any serious concerns will ever be raised high enough to make intumescent 'transit packing' commonplace for residential, not whilst we enjoy open hallways with open staircases at least.