Err,
I thought it was a mandatory requirement for Capt and F/O to have hot mic.
i.e there is always a mic input from these 2 positions for CVR.
This is the case for UK a/c above 11400kgs
That is my understanding of the term 'hot mic', I stand to be corrected however,
(puts on pith helmet and ducks to avoid incomming flack
)