I was doing a rough wire electrical inspection in a gutted house. one that's worth $65,000 and there putting in $125,000. a three floor unit with two out door baloneys. one on the second one on the third.
I find five wires for the alarm system all on the first floor. One to the front door contact, One to the front door area horn, One to the front door area for a PIR, one to the back door.
No key pad upstairs, No PIR up stairs, No smokes. No contacts on either door upstairs. And they call this a system.