Lots (for this group) - thanks. And as you say, it works PROVIDED that one snips - without doing that it's even worse than top-posting.
Oh, and as far as the original question goes - when I put an alarm into the previous place, one of the things I did was to run all the per-sensor wiring back to a handy central point (it was an under-eaves cupboard), where I commoned up the sensors that were to go to each zone (and a single seriesing of all the tampers, ugh!), against the day when I might upgrade the alarm panel from a basic 4-zone job (that's only 2 after you've done final exit and entry area, of course!). We moved out before that ever happened, mind.
But what I did for Maintenance was to include a jack socket and a 12V wall-wart which would supply an independent 'hold off' voltage to the wall-mouned bell unit, breaking the trigger input. That let me fiddle with the alarm panel or other wiring without the bell going orf, as well as providing a backup method of making the bell shut the up should the alarm panel ever get deranged. I'm sure it's not NACOSS compliant, but dammit it was *my* alarm system in *my* house (and I wasn't daft enough to get a 5% discount on the house insurance and lose any chance of ever claiming for a breakin had the alarm not been set, so NACOSS guidelines didn't need to be slavishly followed...)
Cheers, Stefek