Beeps Are Not a Business Continuity Plan: Testing Power Resilience at the Till
Photo: Francisclarke, CC BY-SA 4.0, via Wikimedia Commons
Most UK SMEs have a power plan that fits on a label: a UPS under the desk, a surge-protected extension lead and a mobile hotspot in a drawer. None of these proves that the business can keep trading when the mains supply fails at 11:40 on a Saturday. The till, the card terminal and the person behind the counter are the real test.
Power resilience is often treated as an IT housekeeping matter. In practice, it is a trading continuity control. A retailer, restaurant, clinic or trade counter does not measure outage impact in server uptime percentages. It measures it in abandoned baskets, unpaid tabs, frustrated staff and customers who cannot pay by card. The drill should therefore start where money changes hands, not where the equipment rack sits.
Define success in trading terms
Before testing anything, agree what a successful outcome looks like. For a small retail or hospitality business, that might be: orders can still be recorded, card payments can still be taken for a defined period, staff know when to stop trading and how to close down safely, and data is not corrupted when power returns. For a professional services firm, it might be: calls can be diverted, email remains available on mobile devices, and the team knows which tasks are suspended.
The measures should be equally practical. Record the real runtime of the UPS under normal load, not idle load. Record the time taken for the till system to shut down gracefully. Record how long it takes to restore card payments after power returns. Record how many transactions can be completed in the fallback mode. These figures turn a vague assurance into evidence.
Scenario one: the short interruption
A short outage is the most common event and the easiest to dismiss. It is also the one most likely to expose a badly placed UPS. Test a supply interruption of five to ten minutes during a busy period. Confirm which devices actually remain powered: the till, the card terminal, the router, the phone system, the label printer, the kitchen display or the door access system. It is common to find that the UPS protects the server but not the broadband router, or the till but not the card terminal.
At the counter, the question is simple: can a customer still pay? If the card terminal depends on the router for connectivity and the router is not protected, the terminal may power up but fail to authorise. If the terminal has a SIM fallback, test it with a real transaction. Do not assume that a terminal battery or a mobile backup will work because it has a badge on it. Prove it.
Scenario two: the long outage
A two-to-four-hour outage changes the nature of the test. The UPS will almost certainly run out. The objective is no longer to keep everything running; it is to shut down cleanly and switch to a documented fallback. Test the shutdown sequence for the till system, the network and any local server. Confirm that the shutdown is graceful, that staff know how to initiate it, and that the startup order afterwards is understood.
For card payments, document the policy in advance. Can the business accept offline transactions, and under what limits? Is there a manual payment procedure, and who authorises it? For hospitality, can tabs be opened and settled later? For retail, can customers be directed to an alternative payment method? The drill should reveal whether the fallback is a real procedure or an optimistic sentence in a business continuity plan.
Communications also need testing. If the broadband router is down, VoIP calls may fail even if the handsets have power. Check mobile signal strength inside the building, not just outside. Confirm that the main business number can be diverted to a mobile, and that staff know the diversion code or the supplier contact. Test the card terminal and the phone at the same time, because that is what an outage looks like.
Scenario three: the messy recovery
Recovery is often messier than the outage. Power may return in stages. A circuit breaker may trip. The router may boot before the line is stable. The till may start before the network. Staff may be dealing with a queue while alarms beep and devices reboot.
Test a partial restoration: restore power to the network first, then the till, then the card terminal, and observe what happens. Check for duplicate transactions, missing orders, corrupted files or devices that fail to reconnect. Confirm that the person opening the till knows the startup order and the verification steps. A clean recovery is not just about systems coming back; it is about the business knowing that the systems are safe to use.
The runbook belongs at the counter
The most important output of the drill is not a UPS runtime figure. It is a counter-level runbook that staff can follow without calling an IT supplier first. The runbook should state who decides to stop trading, how to shut down the till, how to handle card payments in fallback, how to divert calls, how to record transactions manually, and who to contact at each stage. It should be short enough to use under pressure and specific enough to prevent improvisation.
Name the roles, not just the tasks. In a small business, the manager, the supervisor and the IT supplier may be the same three people every time. Confirm who is authorised to switch to manual payments, who can close the premises, and who owns communications with customers. Laminate the runbook, keep a copy offline, and review it after every drill.
Turn the drill into governance evidence
A power resilience drill is only useful if it produces actions. Record the date, the scenario, the participants, the timings, the failures and the corrective actions. Assign owners and retest dates. If the UPS runtime is shorter than expected, replace the batteries or reduce the load. If the card terminal cannot work without the router, add a cellular fallback or document the manual process. If staff could not find the runbook, move it.
For 2026, UK SMEs should treat this as part of IT governance rather than a one-off maintenance task. Review the drill after a change of premises, a new till system, a change of broadband supplier or a new card terminal. The till does not care about uptime percentages. It cares whether the next customer can pay. Prove that before the next busy trading day, not after it.
