Reliable IT starts with reliable power: what should stay running during an outage?
Fictional example: the office, its staff and the outage below are invented to illustrate the idea.
Mid-morning, the power goes off at a small accounting office. Four of the six staff work on laptops, which carry on running on their own batteries. The receptionist and the manager use desktop computers, which switch off at once. Then the questions start: “Is the system down?” Every client file, invoice and deadline lives in an online work system, and nobody can reach it.
The online system is fine. So are the laptops. What stopped was the small cluster of equipment in the corner: the router, which connects the office to the internet, and the network switch beside it, which links the office’s devices together. Both run on mains power. When they went dark, every laptop lost its route to the work, and the two desktop users risked losing unsaved work.
This article is for the people who decide how a business copes when that happens. Backing up a service does not mean powering every device in the building. It means finding the equipment the work depends on, deciding how long each piece needs to keep going, and planning what happens if a cut lasts longer than that.
Follow the work, not the plugs
Laptop
Own battery: still on, for now
Router, switch and Wi-Fi
Office mains power: off.
The chain breaks here.Internet provider
Outside the office, on its own power
Online work system
In a remote data centre: still running
A useful term here is critical loads. A load is anything that draws electricity; the critical loads are the equipment that essential work cannot continue without. In this office, the router, the switch and the wireless access point (the device that provides Wi-Fi) are critical loads, because without them nothing else can connect. The laptops are critical too. Their batteries buy time, not necessarily a whole working day, so once they run low the laptops need power as well. An assessment counts them rather than assuming they look after themselves.
Some links in the chain sit outside the premises. The internet provider’s network and the data centre that hosts the online system have their own power arrangements. Backup power in the office can keep the router switched on, but if the provider’s service is down, there is still no internet to reach. Whether the business also needs a second way to connect is a separate decision, though it belongs in the same conversation.
Keep working, or close safely?
Not every business needs its IT running around the clock, and not every outage has to be ridden through. The real question is how much interruption the work can accept.
For the accounting office, a short loss of connection on a quiet afternoon is an annoyance. The same loss on the morning client returns are due is a much bigger problem. Some equipment therefore needs to keep essential work running. Other equipment only needs enough power to shut down safely: time for someone to save open files and close programs properly instead of being cut off mid-task. A lot of equipment can simply wait until power returns.
Keep essential work running
Power for the required working period
- Router and network switch
- Wi-Fi access point
- The provider’s box in the office, if it runs on office power
- Laptops, once their own batteries run low
Allow a safe shutdown
Power long enough to save work and close
- Reception desktop computer
- Manager’s desktop computer
Can wait
Off until mains power returns
- Large printer and scanner
- Air conditioning
- Kettle and microwave
The first group is a short list of mostly small devices. Its “required working period” is something the business agrees during an assessment: perhaps long enough to finish the day’s urgent work, or to cover the kind of cuts the office usually sees. If a cut lasts longer than that, a shutdown plan says who saves what, and in what order, before the backup runs out. A shop whose till and card machine must keep working, or a business that can close for the afternoon without harm, would sort its equipment differently.
How long does it need to last?
Two things decide how long a backup can keep those devices going: how much power the connected equipment draws at once, and how much energy is stored to supply it. Drawing less power makes the same stored energy last longer (US Department of Energy, Solar-Plus-Storage 101). That is why the short list matters. Keeping the router, switch and laptops going is a much smaller job than powering the whole building, and the air conditioning and kettle would use up stored energy far faster.
Runtime also depends on the battery’s condition, how fully charged it was when the cut began and the energy the backup equipment uses itself. Those details belong in the assessment. The business’s part is to say what must keep working, and for how long.
The changeover gap
When mains power fails, the backup has to take over. The brief gap during that changeover is called transfer time. The laptops do not notice it, because they are already on battery. A router or desktop computer can: if the gap is too long for it, it restarts, and the office loses its connection or its open work anyway.
A UPS, or uninterruptible power supply, is built to hold equipment through that moment. Even so, not every UPS or inverter takes over with no gap, and different product ranges list different transfer times (Schneider Electric, Back-UPS transfer-time FAQ). The backup and the equipment it supplies need checking together. How solar panels, batteries, inverters and UPS units share this work is explained in Solar, battery backup and UPS: choosing the right combination for your workplace.
Start from the work
For the accounting office, the useful outcome is not a building that carries on as if nothing happened. It is staff who can keep reaching client files for the agreed period, or save their work and stop calmly, while the kettle waits.
Crownzcom provides solar and battery backup. Its team, which includes electrical engineers, starts by reviewing the equipment a business needs to run, when it needs it and for how long. If power cuts keep interrupting your work, we would be glad to talk it through.