Keyrings.

[Niall]

the main hospital use's a static system using severel type of detectors some are base encoded others are head encoded by dip switchs this system soon tells if the heads arnt right
most of the outbuildings are alarmtec panels which are zoned and use older 2kc's

If you have an Apollo (base encoded) or something like a hochiki (dill switch encoded) you will be alright. Just saying if it's a gent, they can jump addresses. There bloody horrible things! And just because your installing a new detector doesnt mean it will work. I've had that problem many a time!
If I was you, ask them to send you on a basic FIA course because if your signing the book to say you have replaced a head, your legally responisbile and if something goes tits up and there's a fire, there is a chance you can be prosecuted!
Just need to cover your own back mate.