Now bear with me here, because I might be clueless and ranting.

I’m building a vault. I have a good design for the walls, but I’d like to add another layer of protection in case someone tries to breach the walls.

The idea:

-String low voltage wire through the vault walls
-Connect the circuit to a large battery in case of power outage
-Put the battery on a trickle charger
-Wire an inline circuit fault to an alarm horn

My thought being that if someone tries to cut through the walls and accidentally cuts the alarm wire it will cut the circuit and trigger the alarm. Connected to a battery to protect from power outage or thieves intentionally turning off the house power to bypass the alarm.

Am I crazy? Would it work? How would you do it better?

vault monkey.

Sooo, you’re saying you’re available...?

Stale bread and murky water under the door twice a day. Toilet privileges optional dependent on our daily motivation. Bucket provided.

Applications currently being accepted at youreoldandwillprobablydieanyway.com

Throw in an Internet Porn feed and he'll jump at it.

I like it. Keep us informed as to your progress!

Make sure the horn is well protected if you do this. I'd honestly not worry about it and just add additional construction layers to the wall. Rebar, some MST straps, wire mesh etc. If you want to have an alarm, then put a motion sensor in the safe room with a keypad or fob hidden somewhere to arm/disarm. Bonus is, that type of alarm apparatus is off the shelf, no ned to invent a wheel. They will set off that motion by beating on a wall, or upon first hole.

Easy. SPDT solid state relay. Output is your horn. Cut power, horn gets power.

Only downside is, it'll constantly draw power, albeit not much.. maybe 20ma...

I really really like this concept and Techno's idea.

Motion sensor door ringer (like at stores) is in my safe. Chimes when opened. Also, battery powered Wyze came so when it opens it'll start recording. Yes they can take the camera but not where it is stored at.

I saw string the wire but hook it up to a 50,000 V transformer. That arc will scare the crap out if everyone!

My gramps built a Jacob's Ladder gizmo using such a beasty.

Freaking laser beams

I just don’t quite have enough room for the sharks.

Sticky floors would probably be a deal-killer...

If you're using cinder block, reinforce them with rebar and use concrete to fill them. It will take a very long time to cut through that wall even with good powertools. A sledge hammer (or even C4) will get rid of concrete if thin enough, but won't get through the mess of rebar. Those will need to be cut through individually. Two rows of it should stop all but the most determined professional.