Someone would have to be in the right place to trip those devices. I wanted alarms for windows and doors. I have several independent loud alarms if my windows are touched enough to cause even a slight vibration plus the windows can't be raised and my front door can't be kicked open and if it moves even slightly, loud alarms sound. The back of the house has a motion detector with alarm and strobe light which can't be turned off from the outside, and the back door has a vibration detector if the zombie keeps coming and gets to the door.
Think the zombie would go somewhere else (or die if he chose to keep coming). A tactical vest is loaded with what is necessary to keep firing and it's in the area where the doors are.
I was doing re-arranging of things a few days ago and found a body target sheet I used at a gun range. Years ago, I taped it to the outside of my bedroom door and that is what one would see when coming to my bedroom door. Friends laughed at that, but it made a statement. A body would be mostly cut in two by those bullets.