What happens to electronic door locks when the power goes out — do they need backup power?

If doors are hard wired and the power goes out, no doors will work.

However, if a system is hard wired to, say, the building entrance door or garage door, and there is a power outage, the doors would only work if there is a backup power battery. Some buildings have backup power batteries that last a few hours or longer. If this is the case, the system will continue to work as long as the backup power battery lasts.

If a building or apartment door uses a battery operated door handle controlled by a mobile phone, the doors will stop working during a power outage as these doors rely on wifi. Wifi is generally connected to the power and, therefore, would not operate during a power failure.

If the battery operated door handles have a code, fingerprint or fob, these WILL continue to work even in a power outage.

To recap:

1. Hard wired doors would not work in a power outage.
2. Doors with a backup battery will work for as long as the backup power battery lasts.
3. Doors that use batteries to operate the door handles and use their mobile phone to open and rely on wifi will not work if there is a power outage as the wifi replies on power unless the power has a backup battery connected.
4. Doors that use batteries to operate the door handles will continue to work if they can be opened via a pin code, fingerprint or fob. A power outage would not affect these doors.