The new on site guide says "where all circuits are protected by rcd's there is advantage in supplying detectors and alarms from regularly used lighting circuits" page 66
so on one of these twin rcd boards (which personally i don't think comply, circuits should be divided....blah ..blahh to avoid inconvenience etc but customers don't really want to buy all rcbo's! ) you could put power and one lighting on one rcd and the circuits which traditionally (under the 16th) went on the main switch with the lighting circuit incorporating the smokes on the other.
two more points-
page 65 on site guide says " be permantly supplied from an independant circuit from the dist board or supplied from local regularly used lighting circuit(there shold be a means of isolating the suplly to the alarms without affecting the lighting).
what is this all about, blows the theory about the customer not turning turning off the smokes, it will be like fan isolators, which are intended for mechanical maintenance but are used so the fan doesn't wake up the house at night!
point 2 Why shouldn't the smokes be on the same rcd as the sockets ? what reg is this ? what difference does it make, whether the smokes share an rcd with sockets or cooker or lighting circuits for that matter?
i consider myself reasonably intelligent, despite only getting 57 out of 60 in my 17th regs exam the other day ( maybe i should have attended the course and paid £500 rather than self study!) sorry couldn't help a bit of showing off. But as per usual the regs are as clear as mud and i am confused.com!!!!!!!!!!!!!!!!!!
Oh **** it i am going to bed!