In brief
Where to put a fanless 12 V DC box, which cabinet is enough, and how to size a UPS from power draw. What a UPS protects, and why it is a recommendation rather than a condition.
The box arrived, booted and went on a shelf. Most installations end there and run for years without trouble. But because the box's job is to keep records, the physical environment is part of the record too: dust, heat and sudden power cuts hurt it most. This post covers the cabinet and UPS decision for a small business by giving a method, not a brand.
What the box needs
Hotspot-Box is a fanless device powered by a 12 V DC adapter. Those two facts make placement easy:
- No moving parts: no dust-pulling fan, no noise.
- Heat leaves passively through the case; a few centimetres of air around it is enough.
- Power draw is low; the value on the adapter label is the upper bound.
On the other hand, fanless devices are sensitive to ambient temperature. The top shelf of a closed cupboard, next to a radiator or in a sunny window is not a good spot. Put the box where the modem and switch live, upright or flat, with room to breathe.
Cabinet: how much do you need?
For a small business a cabinet is about order, not looks. Three options:
| Option | When it is enough | Watch out for |
|---|---|---|
| Open shelf or wall shelf | One modem, one switch, the box; clean, dry room | Label the cables; limit access by children and cleaning staff |
| Small wall-mount cabinet (6U–9U) | Several APs, a PoE switch and a UPS in one place | A closed cabinet needs vents; keep the key somewhere known |
| Floor-standing cabinet | Only multi-floor or many-AP sites | Unnecessary for most small businesses |
When choosing a cabinet look at ventilation (even a fanless box warms up in a sealed enclosure), depth (the UPS is the deepest item), a lock (a hand pulling the plug by accident is the most common "fault") and cable entry.
Stick a label next to the box: "Law 5651 record device, do not unplug." One short sentence prevents many problems.
What a UPS protects
A UPS is a battery-backed device that keeps supplying power for a short while when the mains fail. For the box it protects three things:
- The disk. Records live on the local disk. Power lost mid-write can corrupt files. A UPS gives the box time to shut down cleanly, or rides through the cut entirely.
- The clock. While running, the box syncs its clock over NTP. With frequent cuts it reboots and waits for connectivity to resync. A UPS removes that churn.
- Chain continuity. When the box runs, it records. When it is off, there are no records for that period. Since guests have no internet either, that is usually harmless; but if the modem and APs are fed from another socket and stay up, guests get online and the box cannot record. That is why the box, switch, APs and modem should share one UPS.
We recommend a UPS; it is not a condition. The box's operation and warranty do not depend on one. But in a place with frequent cuts, running without a UPS means a few unrecorded minutes at every cut and a small but real disk risk.
How to size the UPS
A method rather than a brand. Four steps:
1. Add up the draw. Write down the watt figure from the adapter or power supply label of each device: box, modem, switch, APs (if PoE-powered, they are part of the switch's PoE budget). If the label has no watts, multiply volts by amps.
2. Convert watts to VA. UPS units are sold in VA (volt-amperes). Small devices usually have a power factor of 0.6–0.7. Divide total watts by 0.6 to stay on the safe side.
3. Leave headroom. Multiply by 1.5. A UPS at full load runs briefly, and batteries lose capacity over the years.
4. Check runtime. Battery capacity (Wh) divided by total load (W) gives a rough runtime in hours. The manufacturer's runtime tables are realistic; use them.
Example (illustrative): the labels add up to 60 W. 60 ÷ 0.6 = 100 VA. 100 × 1.5 = 150 VA. Nothing that small is sold anyway; a 500–650 VA unit will run this load for a long time. If APs and a PoE switch push your load to 150 W, the same method gives 375 VA and you look at the 650–1000 VA class.
UPS type and wiring
- A line-interactive UPS is enough for a small business; it also corrects voltage swings.
- Plug the box, modem, switch and APs into the "battery backup" outlets. Use the "surge only" outlets for non-critical devices.
- Do not put printers or laser devices on the UPS; they draw sudden spikes.
- Press the UPS test button once a year; battery life is typically 3–5 years.
Installation-day checklist
- Does the box have airflow, with nothing stacked on it?
- Is the adapter cable slack and not pinched by the cabinet door?
- Are the box, modem, switch and APs on the same UPS?
- Is the cabinet locked, and is the key's location known?
- Is the "do not unplug" label in place?
- Has the UPS been tested, and does the box show online in the panel?
See the box page for the box's physical specifications. If your existing server is already on a UPS, running the same software as a virtual appliance is also an option.