Speaking from recent but intense experience: supposing you, gentle reader, were to have a burglar alarm fitted. I would urge you not to place it on the same mains circuit as a mains/battery-backed smoke detector. Particularly if said detector is so massively over-sensitive as to mistake the merest whiff of the word 'grill' for a major incident requiring the attention of five appliances, thus rendering it imperative to disable said detector when preparing, say, a bowl of cornflakes. And especially if said burglar alarm is of a type that crashes and resets itself when in a low-power state, refusing all attempts to communicate with it via the keypad.
My neighbours must hate me. And the only phone number on the (dreadfully-written and incomplete) alarm manual is now 'not recognised.'
