The cavity and the conduits in there will be cold.
Any water vapour in the conduit will condense into water in the conduit. This will draw in more water vapour through the sockets and other items the conduit connects. This water will accumulate until it over flows into the back of one or more of the sockets.
How fast this happens will depend on temperature and how much water vapour there is in the room.
One lamp fitting in a similar but extreme case produced about 1/4 pint of water per week until a vapour barrier was installed at the far end of the conduit
Any water vapour in the conduit will condense into water in the conduit. This will draw in more water vapour through the sockets and other items the conduit connects. This water will accumulate until it over flows into the back of one or more of the sockets.
How fast this happens will depend on temperature and how much water vapour there is in the room.
One lamp fitting in a similar but extreme case produced about 1/4 pint of water per week until a vapour barrier was installed at the far end of the conduit