A modem and Wi-Fi router are easy to protect with a UPS. A full home network closet is a different problem.

Once you add switches, wireless access points, PoE cameras, a NAS, a firewall, smart-home hubs and other equipment, you have more power draw, more devices that need to shut down cleanly and more reasons to care about what happens when the power stays out for longer than five minutes.

I use UPS units for both my networking gear and my NAS. My current NAS runs TrueNAS on a low-power Intel N100-based system, so it does not require a giant UPS by itself. But the NAS is only one part of the load. The router, switches, access points and other network equipment all need power too.

I have also had both sides of the UPS problem: an unsafe shutdown after losing power and a UPS battery that failed when I expected it to protect the equipment. Those experiences changed how I think about sizing a UPS. Capacity matters, but so do battery condition, monitoring, graceful shutdown and the reliability of the power where the equipment actually lives.

Quick answer: For a home network closet with a NAS, PoE switch and several other devices, a good starting point is looking at a 1500VA-class UPS with sine-wave output, USB or network monitoring and replaceable batteries. The CyberPower CP1500PFCLCD is the value choice I would consider first. For a NAS or server setup where management and expandability matter more, I would step up to the APC SMT1500C or Eaton 5P1500.

When a Router UPS Is No Longer Enough

I have a separate guide to the best UPS for a router and modem. If your entire critical load is an ONT or cable modem, router and perhaps one small switch, start there. You probably do not need the equipment in this article.

A network closet becomes a different problem when it contains things like:

• A modem or fiber ONT
• A router or dedicated firewall
• One or more Ethernet switches
• A PoE switch
• Multiple Wi-Fi access points
• Security cameras
• An NVR
• A NAS
• A small home server
• Home Assistant or other automation hardware
• Smart-home bridges

At that point I care less about finding the smallest UPS that can technically support the equipment and more about building enough margin into the system that it remains useful as the network changes. Also, remember not every device needs to have redundant power.

Start With Watts, Not VA

Measure the actual network load instead of guessing using a smart plug or similar device. Knowing whether the closet uses 90 watts or 350 watts completely changes your considerations.

UPS marketing leads with VA ratings, but the watt rating is just as important. A UPS can be rated at 1500VA and still support a different maximum number of watts than another 1500VA model.

That is visible in the products above. The APC Back-UPS Pro BR1500MS2 is rated for 900 watts, the CyberPower CP1500PFCLCD and APC Smart-UPS models here are rated for 1000 watts, and the Eaton 5P1500 is rated for 1100 watts.

You do not want to add the wattage printed on every power adapter and assume that is your actual load. Those labels generally describe what the power supply can provide, not necessarily what the device consumes continuously.

Measure the whole network closet

If everything is already connected to one UPS, the UPS display may show current load. You can also use a plug-in power meter between the wall and the equipment while temporarily running it without the UPS.

Measure during normal operation and then consider what changes under load. A NAS may draw more power while its disks are active. A PoE switch may consume considerably more as additional cameras and access points draw power.

I would also leave room for the next device. Home networks have a habit of growing.

PoE Makes UPS Sizing More Interesting

A normal Ethernet switch has a relatively predictable load. A PoE switch is powering other equipment through the network cable, so the switch itself is only part of the calculation.

If the switch powers cameras, wireless access points, phones or other PoE devices, that downstream load is also being supplied by the UPS.

This is one reason backing up the switch can be so useful. One UPS connection may keep an entire group of cameras and access points online. It also means that adding another six PoE cameras later can materially change the amount of battery runtime you have.

When sizing the UPS, look at actual PoE consumption rather than simply the switch’s maximum advertised PoE budget. Then leave enough capacity for growth.

A NAS Changes What I Want From a UPS

A router reboot is annoying. An abrupt NAS shutdown is something I work harder to avoid.

A NAS may be writing data, updating filesystem metadata or running applications when utility power disappears. The goal of the UPS is therefore not necessarily to run the NAS for hours. It may be to keep the machine alive long enough for the outage to prove that it is not a momentary flicker and then shut the system down cleanly.

This is why I consider communications support essential when a NAS or server is part of the load.

TrueNAS and NUT

TrueNAS includes UPS support using Network UPS Tools, commonly called NUT. A compatible UPS can communicate with the NAS over USB, serial or, with suitable hardware, over the network.

TrueNAS can then react to UPS status and initiate a controlled shutdown rather than waiting for the battery to become completely exhausted.

The exact UPS and driver still matter. If automatic shutdown is important to you, check the current TrueNAS UPS documentation and the Network UPS Tools compatibility information before buying.

TrueNAS can also operate with one system acting as the UPS monitor while other systems receive status across the network. That is useful when several servers share one sufficiently large UPS.

If you are interested in the NAS side of my setup, I have an entire Building My NAS series covering the hardware and software decisions.

How Much Runtime Do You Actually Need?

This is where I think a lot of UPS recommendations go wrong. The correct size depends on the power where the equipment is located.

A network closet in a city apartment with an occasional one-second flicker has a very different problem from equipment sitting unattended at a vacation house where an outage might last six hours.

If your problem is brief flickers

Your main goal is continuity. You want the modem, router, switches and NAS to ignore a brief voltage drop that would otherwise reboot everything.

Runtime is secondary. Even a modest amount of battery capacity may be enough, although I still prefer reasonable headroom rather than running a UPS near its maximum load.

If you get occasional short outages

Now runtime becomes useful. If most outages last five or ten minutes, I want the network to stay up rather than immediately begin shutting things down.

A 1500VA-class unit becomes attractive because a network closet usually draws far less than the UPS’s maximum watt rating, allowing more runtime than it would provide to a heavily loaded desktop computer.

If outages are frequent

Battery wear and monitoring become more important. Every battery discharge uses part of the battery’s useful life.

This is also where Automatic Voltage Regulation is valuable. A line-interactive UPS with AVR can correct certain voltage variations without moving to battery every time the incoming voltage wanders outside its preferred range.

For a deeper look at AVR, waveform, communications and other UPS features, see How to Choose a UPS With the Right Features.

If long outages are common

A larger UPS may delay the shutdown, but eventually this stops being primarily a UPS-sizing problem.

If the power regularly disappears for hours, you may need a generator, a much larger battery system or another backup-power strategy. The UPS can bridge the gap, protect the equipment from short disturbances and give servers time to shut down properly.

If the network is at a remote or vacation property

This is the case where monitoring becomes especially valuable.

If nobody is there to hear the UPS beeping, I want some way to know that the property lost power and that the battery is being depleted.

There is another limitation: keeping your router alive does not guarantee that your internet service remains alive. Your cable company, fiber provider or other ISP has equipment upstream from your house. A neighborhood-wide outage may eventually take that infrastructure offline too.

If remote connectivity is important enough, consider cellular failover as a separate layer.

I discuss the rest of that problem in my guide to vacation-home remote monitoring.

Best Value: CyberPower CP1500PFCLCD

For many home network closets, the CyberPower CP1500PFCLCD is where I would start.

It provides 1500VA/1000W capacity, sine-wave output, Automatic Voltage Regulation, 12 outlets and USB communications. CyberPower also supports optional network management for the model.

That is a lot of capability for a home network, NAS and PoE setup without moving all the way into enterprise UPS pricing.

I would buy it for: a serious home network closet where value matters and USB shutdown is sufficient.

Check the CyberPower CP1500PFCLCD on Amazon

Best Consumer Step-Up: APC Back-UPS Pro BR1500MS2

The APC BR1500MS2 sits between the small consumer UPS and the more IT-oriented Smart-UPS line.

It is rated at 1500VA/900W, has 10 outlets, AVR, an LCD and a user-replaceable battery.

If your closet is mostly networking gear with perhaps a low-power NAS, this may be enough. If I were protecting a more substantial server or knew I wanted network-management options, I would move up to the Smart-UPS or Eaton choices below.

I would buy it for: a large home network that has outgrown a basic router UPS but does not need the management features of a higher-end unit.

Check the APC BR1500MS2 on Amazon

Best APC for a NAS or Server: APC Smart-UPS SMT1500C

The APC SMT1500C is where the product starts to feel more like network infrastructure.

It is a 1440VA/1000W line-interactive sine-wave UPS with eight outlets, AVR, a replaceable battery, USB/serial shutdown support, a SmartConnect Ethernet port and a SmartSlot for additional management options.

The difference is not simply another hundred watts. I am paying for a platform designed around servers, storage and network closets.

I would buy it for: a NAS or server I care about enough to justify spending more for management, monitoring and a more IT-oriented UPS platform.

Check the APC SMT1500C on Amazon

Premium Tower Choice: Eaton 5P1500

The Eaton 5P1500 is the premium tower option in this group.

It is rated at 1440VA/1100W, has eight outlets and true sine-wave output. Eaton includes USB and serial connectivity, with an optional network card for remote management.

The higher watt rating also gives a little more room for equipment growth, although runtime still depends on the actual load.

I would buy it for: a serious home lab or network closet where management, build quality and server-oriented features justify the higher cost.

Check the Eaton 5P1500 on Amazon

Best Rackmount Choice: APC SMT1500RM2UC

If the network already lives in a rack, the APC SMT1500RM2UC is the cleanest choice here.

It is a 2U rackmount Smart-UPS rated at 1440VA/1000W with six outlets, sine-wave output, AVR, SmartConnect, SmartSlot expansion and USB or serial shutdown support.

The advantage is organizational as much as electrical. Instead of putting a heavy tower on the floor or a shelf beside the rack, the UPS becomes part of the rack itself.

Remember that a rackmount UPS is heavy. Install it low in the rack and make sure the rack and mounting hardware are designed to support it.

I would buy it for: a permanent rack-mounted network installation where clean organization and IT-style management matter.

Check the APC SMT1500RM2UC on Amazon

Tower vs. Rackmount UPS

Do not buy rackmount simply because it looks more professional. Tower units generally give a home user more flexibility and often better value.

Should You Use a Rack PDU?

A rack PDU can make sense when the UPS does not provide enough conveniently located receptacles for all the low-power equipment in a rack.

A proper PDU is a power-distribution device, not another UPS. Eaton specifically describes a UPS feeding a PDU as a normal basic network-closet architecture, and APC also distinguishes rack PDUs from ordinary surge strips.

Do not solve an outlet shortage by daisy-chaining UPS units. Do not casually add a household surge strip or extension cord to the output either. UPS manufacturers have specific requirements for what can be connected to their equipment.

If you need more outlets, check the UPS manufacturer’s guidance and use an appropriately rated PDU intended for the application.

Do You Need Pure Sine Wave?

For a simple modem and router, I would not make waveform the only buying criterion.

Once a NAS, server or other equipment with an active-PFC power supply is involved, I prefer a sine-wave UPS. It removes a compatibility question and is already standard on the CyberPower CP1500PFCLCD, APC Smart-UPS models and Eaton 5P1500 covered here.

This is one of those features where I would rather buy it once than diagnose a strange shutdown later.

Battery Replacement Matters More Than the UPS Brand Name

A UPS is not a permanent appliance. Its battery is a consumable.

I learned this the irritating way when equipment protected by a UPS went down even though there had not been an obvious outage. The UPS was still sitting there doing its job in theory. The battery was no longer capable of doing its job in practice.

I wrote about that experience in UPS Batteries May Only Last 2–3 Years — And They Usually Fail Without Warning.

For a network closet, I would:

• Buy a UPS with replaceable batteries
• Write the battery installation date on the UPS
• Enable battery and self-test alerts
• Check reported battery condition periodically
• Test whether the UPS can actually carry the network load
• Replace a weak battery before an outage exposes the problem

A UPS showing a green light is not the same thing as a UPS with a healthy battery.

What Should Be on Battery Backup?

Prioritize the equipment that either keeps connectivity alive or needs an orderly shutdown.

For my network closet, the battery-backed side would include:

• ONT or modem
• Router or firewall
• Core network switch
• PoE switch if it powers critical cameras or access points
• NAS
• Essential Wi-Fi access points
• Home-automation controller
• Critical monitoring gateways

I would be much less interested in using battery capacity for:

• Monitors that do not need to stay on
• Printers
• Speakers
• Decorative lighting
• Chargers that can wait
• Nonessential lab equipment

What Should Never Be Connected to a Normal Network UPS?

A UPS designed for computers and networking equipment should not become a general emergency outlet.

High-draw heating and motor loads can quickly overload it. I would not connect things such as:

• Laser printers
• Space heaters
• Vacuum cleaners
• Refrigerators or freezers unless the UPS was specifically selected for that load
• Air conditioners
• Large pumps
• Other appliances with substantial startup current

Keep the UPS focused on the network and computing equipment it was purchased to protect.

Ancillary Gear I Would Buy With the UPS

The UPS is the major purchase, but a few inexpensive additions make the installation better.

A plug-in watt meter

Measure the actual network load instead of guessing. Knowing whether the closet uses 90 watts or 350 watts completely changes the runtime discussion.\

A proper rack PDU if you need more outlets

For rack installations, use suitable power distribution rather than a pile of consumer power strips. Follow the UPS manufacturer’s recommendations for connected distribution equipment.

An optional network-management card where it adds value

This is most useful when the UPS sits in a remote location, supports several machines or needs to be monitored without depending on one USB-connected computer.

The Eaton 5P supports an optional network card. APC’s Smart-UPS models include SmartConnect and a SmartSlot for additional management options. CyberPower supports optional remote network management on the CP1500PFCLCD.

A replacement-battery reminder

Put a calendar reminder in place when the UPS is installed. Waiting until the battery fails defeats a large part of the reason you bought the UPS.

My Buying Decision

If I were building a normal home network closet today, I would buy the CyberPower CP1500PFCLCD first. It gives me the combination of capacity, sine-wave output, communications and price that makes sense for most home setups.

If the NAS or server were more important, or if I expected to invest in better UPS management, I would move to the APC SMT1500C or Eaton 5P1500.

If the entire installation were rack-mounted, I would strongly consider spending the extra money on the APC SMT1500RM2UC rather than finding somewhere to put a tower.

But I would make that decision only after measuring the actual load.

A 1500VA UPS is not automatically better because the number is larger. The goal is to buy enough capacity and runtime for the equipment, give the NAS time to shut down cleanly, and make sure the UPS can tell you when its battery is no longer ready to do the job.

Frequently Asked Questions

What size UPS do I need for a home network closet?

Measure the actual wattage of the modem or ONT, router, switches, PoE devices, NAS and other equipment you want to protect. For a larger network closet containing a NAS and PoE equipment, a 1500VA-class UPS is a useful starting point, but the correct size depends on both total watts and the runtime you need.

Is a 1500VA UPS overkill for a router and modem?

Usually. If you are only protecting a modem or ONT and Wi-Fi router, see our router and modem UPS guide. The larger units in this article make more sense when a NAS, PoE switch, cameras, access points or servers are part of the load.

Should my NAS be connected to a UPS?

Yes, if the NAS contains data you care about. A UPS can protect it from brief outages and, with compatible communications and software, provide enough warning for a controlled shutdown during a longer outage.

Can TrueNAS shut itself down when the UPS battery is low?

Yes. TrueNAS uses Network UPS Tools for UPS monitoring and shutdown functions. Verify that your exact UPS is supported and configure and test the shutdown behavior before depending on it.

Should a PoE switch be on the UPS?

If the PoE switch powers equipment you want available during an outage, such as cameras or Wi-Fi access points, putting it on battery backup can protect all those devices at once. Remember that their combined PoE consumption is part of the UPS load.

How long will a UPS run my network?

Runtime depends on UPS model, battery condition and actual load. Do not estimate it from the VA rating alone. Measure the network’s wattage and use the manufacturer’s current runtime chart or calculator for the specific UPS.

Should I buy a rackmount or tower UPS?

Buy a tower UPS if you want flexibility and value. Buy rackmount when the network already lives in a rack and the cleaner installation is worth the added cost and rack space.

Will a UPS keep my internet working during a blackout?

It can keep your equipment powered, but it cannot guarantee that the ISP’s upstream infrastructure stays online. For a remote property where connectivity is critical, consider cellular failover in addition to UPS backup.

Can I plug a surge protector into a UPS?

Do not assume that an ordinary surge strip or extension cord is acceptable. Manufacturers including APC and CyberPower warn against common surge-strip configurations with their UPS products. If you need more rack outlets, use an appropriately rated PDU and follow the UPS manufacturer’s instructions.

How often should I replace a UPS battery?

Battery life varies with battery chemistry, temperature, discharge frequency and UPS design. Instead of relying only on age, monitor the UPS, perform tests and make sure the battery can still support the actual load. Replace a weak battery before you need it during a real outage.