Closed loop embedded in a concrete wall

I will have access to a concrete foundation wall space before the pour and I would like to embed a simple closed loop trip circuit to deter against the remote possiblity of a break in from the basement. (This is a commercial installation. The wall will be at least 8" thick and have rebar inside for strength.

What type of wire/cable would be best?

Here are my concerns.

I don't want to use bare copper in the concrete because of oxidation/deterioration concerns and the possiblility of accidental grounds.

The wire or cable should be mechanically thick enough to last a long time (many many years), but readily break if the wall is attacked with drilling, sledge hammers, etc.

What materials would be best for concrete? Would you use a plastic or metallic sheath? ...Possibly PVC?

Any suggestions or advice would be greatly appreciated.


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I'd put it in conduit. You really think someone's gonna crack through the basement concrete?

Reply to
Crash Gordon

Yeah... Vault vibration sensors spaced evenly around the perimeter. If they do dig through the concrete and happen to "miss" your simple "sensor loop", you're gonna look like a "monkey". I guess this place must contain the Crown Jewels, or Imelda Marcos's off-shore shoe collection.

Reply to
Frank Olson

Yeah...Well Imelda loves her shoes What can you do?

I looked into a Honeywell vibration detection system for vaults and safes. Expensive... but it does everything apparantly, detects seismic disturbances, vibrations and explosions... even prints out a log of events.

At the other end of the market are the cheapo vibration detectors that require a pulse stretcher, made by Ademco, among others, I think..

I was just looking for some extra protection for the concrete wall... sort of like a concealed screen.


Reply to

sounds like an old "bank night drop" loop.. first thing is to run several loops with each end out then make the splices outside the slab. that way you can remove any bad loop later as the ckt rots out.. if memory serves several of the old bank service companies use to use a hard drawn copper in a rubber/pvc jacket. about a 20 ga solid. If your using a rebar in the concrete then weave the loop in and out of the rebar but try not to touch the rebar as the concrete is poured.. you could also try and have the concrete supplier to add a lot of flint to the mix. will play hell to anyone trying to drill the slab.. and if you really want to go old school make all the pig tails the same color.. LOL makes it a bitch to check loops once the net is set..


Reply to
Rocky T Squirrel

You don't have to re-invent the wheel. There are old guys that worked for Mosler, Diebold and such that have built what you seem the be trying to build. I'd talk to one of those guys. No one here in the NG has ever mentioned being in the vault construction business. I have done some work in vaults of all kinds, as I suspect many other here too have, but that is only after they're built.

Reply to
Roland Moore

What you are looking for is called an "embedded cable' system. These were used in the days before electronic sound and vibration detectors became available. The preferred type of cable was lead-sheathed, because it's waterproof. That may no longer be available due to environmental regulations; I don't know. Several separate loops of cable were installed, so that if one loop failed, there would be spares. The wires were spaced about 4" apart, a few inches in from the outer surface of the wall. Cable junction boxes were typically installed so they were accessible from the inside of the vault, with each wall having its own set of loops. The cable had to be monitored while the concrete was being poured, in case of damage.

As you can imagine, this was a hell of a lot of work. Self-contained electronic vibration detectors such as GE/Sentrol/Aritech's Advisor X, do a great job with a lot less work.

- badenov

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