MaintenanceFor Property Managers

What Happens to Your Security System When the Power or Internet Goes Out

The lights go out. Do your doors lock or unlock? Do the cameras keep recording? Does the alarm company still know? Here is what actually happens in an outage, and what to test before the next one.

PAX Security7 min readAugust 28, 2026

Quick Answer

In a power outage, anything without battery backup stops. Cameras go dark, the recorder stops saving footage, and electric door locks either unlock or stay locked depending on how they were set up. Alarm panels usually have a backup battery that lasts hours, not days. In an internet outage, most systems keep working on site, but remote viewing, cloud alerts, and sometimes alarm monitoring stop. Test your backups before you need them.

Key Takeaways

1Battery backups for cameras, the recorder, and network gear decide whether you have footage of an outage
2Fail-safe doors unlock when power is lost; fail-secure doors stay locked. Know which ones you have
3Alarm panels have their own backup battery, but it only lasts so long and batteries wear out
4An internet outage often cuts off remote viewing and alerts even if everything on site keeps running
5A short test once a year tells you exactly what will happen in the real thing

Here is a question most property managers cannot answer: if the power goes out in your building at 11 p.m., do the doors lock or unlock?

Not what you hope happens. What actually happens. Most people find out during the outage, which is the worst time to learn.

Power and internet outages happen. A storm. A blown transformer. Con Ed work down the block. A contractor who unplugs the wrong thing in the basement. Your security system was built with assumptions about what happens next. It is worth knowing what those assumptions are.

When the power goes out: what stops and what keeps going

Anything plugged into the wall without a backup stops immediately. That usually includes:

Cameras, if they get power from a switch or recorder that is not on backup
The recorder, which means no footage is saved while it is down
Network switches and the internet router
Intercom stations, unless they have their own backup
Electric door locks and readers, depending on how they are set up

The alarm panel is the exception. Almost every alarm panel has a small battery inside that keeps it running for a while after the power goes out. How long depends on the panel and the age of the battery. A fresh one might last many hours. A five-year-old one might last much less.

If your recorder goes down, your cameras stop recording, even if the cameras themselves still have power. An outage is exactly when someone might try something, and it is exactly when you will have no footage unless the recorder is on backup.

Battery backups: the small box that matters most

A battery backup, sometimes called a UPS, is a box with a battery that sits between the wall and your equipment. When power cuts out, the battery takes over instantly. Nothing reboots. Nothing loses footage.

For a security system, the key things to put on backup are the recorder, the network switch that powers the cameras, the internet router, and the access control panel. If those four keep running, your cameras keep recording and your doors keep working for as long as the battery lasts.

Battery backups do not last forever. The batteries inside wear out, usually in a few years. A backup with a dead battery looks fine until the day it does nothing. Most have a test button or a warning light. Someone should check it.

Doors: fail-safe vs fail-secure, explained simply

Electric locks need power to do their job. The question is what they do when power is gone. There are two answers.

Fail-safe means the door unlocks when power is lost. The "safe" part is about people: nobody gets trapped inside. These are common on main exits and stairwell doors, often because fire and building codes require doors on the exit path to let people out.

Fail-secure means the door stays locked when power is lost. The "secure" part is about property. These are common on storage rooms, server closets, and offices. People can usually still get out from the inside using the handle, but nobody can get in from outside without a key.

Neither one is wrong. But you need to know which doors are which. If your front door is fail-safe and the backup battery on the access panel dies, your building is unlocked until power comes back. That might be fine. It might not be. You should decide that on purpose, not find out by accident.

Fire and life safety rules decide how some doors must behave in an outage, and those rules come first. Your installer and your local building and fire codes set the requirements here, so do not change how an exit door behaves without checking.

When the internet goes out

Losing internet is less dramatic but more common. In most systems, everything on site keeps running. Cameras record to the local recorder. Doors open with cards. The alarm still sounds.

What stops is everything that talks to the outside world:

You cannot view cameras from your phone
Motion alerts and notifications do not arrive
Cloud-managed access systems cannot be changed remotely, though readers usually keep working with what they already know
Alarm monitoring may lose contact if the panel only reports over the internet

That last one is the big one. If your alarm panel only talks to the monitoring center over your internet connection, an outage means a break-in might not get reported. Many panels have a cellular backup that kicks in automatically. Ask your monitoring company whether yours does, and whether it is active.

When the power comes back

The outage is not over when the lights come on. Equipment has to restart, and not all of it does so cleanly. A recorder can come back with the wrong date and time, which makes footage harder to find later. A camera can fail to reconnect. An access panel can come back up while the internet is still down and be unable to sync changes.

After any outage, have someone take five minutes to check that every camera shows live video, that the recorder is recording, and that a card still opens the front door. It is a lot easier to catch a problem that day than a month later when you need footage.

What to test before the next outage

You can learn most of this in an afternoon. Pick a quiet time, tell tenants or staff, and walk through it with whoever services your system.

Unplug the battery backup from the wall and see what stays on, and for how long
Check each electric door with power off: does it lock or unlock?
Unplug the internet and ask your monitoring company if they still see your panel
Check the date on alarm panel and backup batteries, and replace any that are old
Confirm the recorder comes back on by itself and keeps recording after power returns

Write down what you find. The next time the lights go out, you will know exactly what is happening at every door and camera, instead of guessing.

You should decide what your doors do in an outage on purpose, not find out by accident.

Your Checklist

Confirm the recorder, network switch, router, and access panel are on battery backup
Check the age of every backup battery and alarm panel battery
Make a list of which doors are fail-safe and which are fail-secure
Ask your monitoring company whether your alarm has a cellular backup
Run a short power-off test with your service provider once a year
Make sure the system restarts on its own after power returns

Common Mistakes to Avoid

Putting cameras on backup but not the recorder

Cameras that stay on but have nowhere to save footage are just watching. The recorder and the network gear need backup too.

Never replacing backup batteries

Batteries wear out in a few years. A backup box with a dead battery gives no warning until the outage, when it does nothing.

Not knowing which doors unlock in an outage

If your main entry unlocks when power fails and the backup runs out, your building is open. Know this ahead of time and plan for it.

Relying on internet-only alarm monitoring

If the panel only reports over your internet, an outage can cut it off from the monitoring center. A cellular backup closes that gap.

Frequently Asked Questions

How long will a battery backup keep my security system running?

It depends on the size of the backup and how much equipment is plugged in. Some setups run for minutes, others for hours. Your installer can size it so the critical pieces last as long as you need.

Will I lose old footage if the power goes out?

Usually not. Footage already saved on the recorder stays there. What you lose is anything that would have been recorded while the system was off.

Can I change a door from fail-safe to fail-secure?

Sometimes, depending on the lock hardware. But exit doors may be required by code to unlock in an outage, so check with your installer and local codes before changing anything.

Do key cards still work when the internet is down?

In most systems, yes. The door controllers keep a local copy of who is allowed in. What you lose is the ability to make changes remotely until the connection comes back.