Security Fog for Cash Rooms
Cash rooms are the textbook use case for security fog. A small sealed room with high-value contents and a single entry point is exactly where fog dominates — the room fills to zero visibility in 3-5 seconds, well before any attacker can identify the counting station, the safe, or the cash drawers.
Why cash rooms need fog
The cross-industry cash-room problem: retail, gaming, dispensary, bank, and warehouse all have a back-of-house counting and handling area that holds the highest concentration of fungible value in the operation. Despite the high stakes, cash rooms typically have:
- One entry point
- One or two staff during active handling
- Light camera coverage (privacy considerations during counting)
- Limited perimeter sensors (the room is interior to a larger building)
- Standard commercial safe as the only physical defense
That’s a soft target by any retail standard, and exactly the geometry where security fog is most effective.
The sealed-room advantage
Fog deployment performance depends heavily on room conditions. Cash rooms are ideal because they are:
- Small (typically 10-40 m²). A 2-can fog unit reaches zero visibility in 3-5 seconds, not 10.
- Sealed. Standard cash-room build-out includes solid-core doors, sealed walls, and minimal HVAC penetration. Fog density holds longer than open retail.
- Low-ceiling. Typical 2.4-3.0 m ceilings concentrate fog density at attacker eye level.
- Single-attack-vector. One door, one window (if any). Fog blocks the only path and the only target simultaneously.
Counting-room placement
The fog unit’s job in a cash room is to block visibility between the attacker and the counting station / safe. Standard placement:
- Wall-mounted unit on the wall opposite the entry door, at 2.0-2.4 m height, nozzles aimed across the room
- 2-can mode for rooms under 200 m³ (which is essentially all cash rooms); 4-can if the room exceeds 200 m³
- Trigger: door-contact + interior PIR. Some installs add a panic switch under the counting table for active armed-encounter scenarios.
- Fire alarm coordination: standard timed shunt on the cash-room smoke detector during deployment
Dual-control & access protocols
Strong cash-handling operations use dual-control protocols — two staff present, two access credentials required, alternating duty assignments. Security fog fits this model:
- The fog system is disarmed only during dual-control handling windows
- Auto-arm whenever the room is unoccupied
- Panic switch fires the fog even during armed presence (e.g., if a robbery interrupts an active dual-control counting session)
- Tamper protection on the fog unit itself prevents disarming via housing removal
See also: banks · cannabis dispensaries · vs safes · buyer’s guide.
Frequently asked questions
Will fog damage cash, checks, or counting machines?
No. Food-grade glycol fog leaves no residue on paper currency, checks, or bill-counting machine internals. Counting machine optical sensors recover within seconds of fog clearing.
How small is too small for a cash-room fog install?
Even a 6 m² closet-sized cash room benefits from fog. Smaller rooms reach zero visibility in 2-3 seconds with a 2-can unit, making them effectively impossible to operate in. There's no minimum size below which fog stops being effective.
Can the fog system run on the same alarm panel as the main building?
Yes. Most cash-room fog installs share the main building alarm panel and use one of its programmable outputs as the trigger. A dedicated cash-room zone makes false-trigger isolation easy.
What if two staff are inside during dual-control counting when an external attack starts?
The under-counter panic switch is designed for exactly that scenario. Staff press the button, fog fires within 2-3 seconds, and both staff have immediate cover to retreat or hold position behind the counting table. The fog blocks the attacker's targeting more than it impedes the staff's familiar movements in their own room.
