A summer storm rolls through Baton Rouge at 2 p.m. The lights flicker for half a second and come right back. Nobody thinks about it until the front desk computer reboots, the phones drop, and the server in the closet comes back up with a corrupted database. A UPS battery backup would have kept all three running.
An uninterruptible power supply (UPS) is built for that half second. It sits between the wall outlet and your equipment and switches to battery the instant power drops or sags, so connected devices never notice. It is one of the least exciting pieces of equipment in an office and one of the cheapest ways to avoid downtime and damaged hardware.
What a UPS battery backup does, and what it doesn’t
A UPS keeps equipment running through blinks, sags and short outages. With shutdown software or a network management card, it can tell servers and storage to shut down safely before the battery runs out. Most units also smooth out spikes and low-voltage periods that wear out power supplies over time.
What a UPS won’t do is carry your office through a long outage. Small units are built to bridge minutes. That short window covers the flickers that cause most problems and gives systems time to shut down properly when the outage is going to last.
Which type of UPS you need
Schneider Electric’s long-running APC white paper on UPS designs describes several types. These three are the ones you will see when buying for an office.
| Type | How it works | Best fit |
|---|---|---|
| Standby | The battery switches on only when power fails. Small, efficient and inexpensive, with little voltage correction. | A single desk |
| Line-interactive | Adjusts voltage up or down without using the battery, so it handles brownouts and sags well. The white paper calls it the dominant design in the 0.5 to 5 kVA range. | Network closets and small servers |
| Double-conversion online | All power runs through the inverter all the time, so output stays clean and there is no switchover. Costs more and runs warmer. | Servers, storage and power-sensitive equipment |
What to plug in, and what to leave off
Start with whatever keeps the organization connected. If the network goes down, every computer in the building loses email, cloud apps and phones, even if the computers themselves stay on.
- The firewall, network switches and the internet provider’s modem or router
- Wi-Fi access points and the switches that power them
- Phone system equipment and the switch that powers desk phones
- Servers, network storage and backup appliances
- Workstations for people who can’t lose unsaved work, such as billing or reception
Leave laser printers off. APC advises that laser printers should not be plugged into a UPS’s battery outlets or its surge-only outlets, because their heavy bursts of power can overload the unit. A separate surge protector is enough. The same goes for space heaters, coffee makers and other high-draw appliances.
How to size a UPS
Capacity is listed in VA and watts. Watts is the number to match against your load.
- List the devices you need to protect and add up their actual wattage.
- Choose a unit where that total sits around 80% of its rating or less.
- Decide how much runtime you need. Riding through flickers and shutting down cleanly is the usual goal.
- Add an external battery pack if you need more minutes.
- Set up shutdown software or a network management card so servers power down on their own when nobody is in the office.
Schneider Electric recommends that headroom because a unit at full capacity runs hotter, less efficiently and for less time. In one of its examples, the same unit ran about nine and a half minutes at 80% load and six and a half minutes at full load.
Why UPS batteries fail when you need them
The most common UPS failure has nothing to do with size. It is a unit that sat in a closet for six years with a worn-out battery, beeping into an empty room. When the power finally drops, it shuts off with everything else.
Schneider Electric says most APC batteries should last three to five years and recommends replacing them before they reach five. Heat matters most. The optimal range is 68 to 77°F, and every 15°F increase cuts battery life in half, so a unit in a hot, unventilated closet wears out much sooner.
- Write the install date on the unit and in your asset list.
- Run a self-test a few times a year and check battery status in the UPS software.
- Send UPS alerts to someone who will act on them.
- Plan battery and unit replacements as part of your IT refresh plan.
Track UPS age alongside your other hardware so batteries get replaced on schedule instead of failing mid-storm. That is the same discipline behind good lifecycle management. For our clients, we monitor UPS units remotely so battery and power alerts reach us instead of an empty closet.
Where a UPS fits in storm planning
11 hours
average time a U.S. electricity customer went without power in 2024, with major events such as hurricanes making up about 80% of it (EIA)
Atlantic hurricane season runs June 1 through November 30, and afternoon thunderstorms cause plenty of short outages in between. A UPS handles the short ones. For the long ones you need backups of your data, cloud services staff can reach from home, secure remote access and, if the office must stay open, a generator with a transfer switch. The UPS bridges the seconds before the generator takes over.
When a named storm is headed our way, UPS checks are on our client checklist, alongside controlled shutdowns and verifying backups. Our hurricane disaster recovery plan post has the full timeline, and the essentials of a business continuity plan covers the rest of business continuity planning.
If you aren’t sure what in your closet is on battery power, or how old those batteries are, it’s worth a look before the next storm. Book a 20-minute call and we’ll talk through it, or see how storm preparation fits into our managed IT services.
FAQ
Frequently asked questions
Can I plug a power strip into a UPS?
Schneider Electric recommends against plugging any surge protector, power strip or extension cord into a UPS, and says to plug the UPS straight into the wall. If you need more outlets, use a larger unit or a proper power distribution unit.
What is the difference between a UPS and a surge protector?
A surge protector only absorbs voltage spikes. A UPS also supplies battery power during outages and, depending on the type, corrects low and high voltage.
Sources: Schneider Electric (APC), White Paper 1: The Different Types of UPS Systems; Schneider Electric FAQ: Things to consider in sizing a UPS and load; Schneider Electric FAQ: Expected life of APC UPS VRLA batteries; Schneider Electric FAQ: Recommendations for protecting a laser printer; U.S. Energy Information Administration, Hurricanes in 2024 led to the most hours without power in 10 years, 2025; NOAA AOML, Hurricane FAQ; Schneider Electric FAQ: Using surge strips with Back-UPS and Smart-UPS products.
