What Happens to a Smart Home When There's a Power Cut

The Impact of a Power Cut on Your Smart Home System

When the mains power supply fails, the behaviour of your smart home devices can vary significantly, depending on whether they rely solely on grid power or have built-in backup options.

What Keeps Running

• Battery-Powered Devices: Devices such as smart locks, wireless sensors and some security cameras come with internal batteries. Though they may not have full functionality, they can continue operating at a reduced capacity during a power outage.
• UPS (battery) Protected Devices: Items like your smart hub and broadband internet router can be kept running on a UPS (Uninterruptible Power Supply). When properly backed up, these devices maintain network connectivity and can sustain automations that rely on cloud processing.
• Cloud Functions: Many smart home automations utilise cloud servers for data processing and remote control. These services typically remain available because they are hosted in data centres with their own redundant power systems. However, if your local gateway or router isn’t backed up, the link between your home and the cloud is interrupted.

What Won’t

• Mains-Powered Appliances: Any device that depends directly on the electrical grid (e.g. smart lights or home assistant, smart plugs etc) will immediately go offline.
• Local Automations: If your smart hub loses power, local automations that rely on the hub’s processing will halt, regardless of whether the devices themselves have battery backups.
• Notifications and Alerts: Without power, notifications can be delayed or completely fail.

Quick Reference Table

Remote Access and Notifications During a Power Cut

The loss of power to your home network components means that:

• Remote Access Automatically Disrupts: Unless your router and modem are on a backup power system (like a UPS or a mobile hotspot), you won’t be able to communicate with your devices.
• Delayed or Missing Notifications: Alerts triggered by automations or security systems may will be sent if the devices invoking them are offline.

Redundancy is key here. Consider setting up a secondary connection (e.g. a cellular-based router or smart device with independent connectivity) so that you can receive crucial updates even when your primary system is down.

Mitigating Power Outages: UPS, Battery Backups and More

1. Invest in a UPS (basically a battery): A quality UPS can keep your smart hub, WiFi router and modem operational for several hours or even days if large enough. When these critical components remain powered, your home retains at least partial connectivity to cloud-based services and remote access.
2. Battery Backup for Critical Devices: Devices such as smart locks, security cameras and even select smart sensors often have built-in batteries. Ensure that you have spare batteries handy and that you monitor battery health regularly.
3. Smart Power Strips and Surge Protectors: These devices can help protect your gear from power surges when the power returns—a frequent issue that can damage electronics.
4. Redundant Internet Options: Consider a mobile data hotspot as a backup solution for your home network. This is especially useful if you frequently need to check in on your home remotely.
5. Automated Alerts from UPS Systems: Many modern UPS devices come with software that can notify you of a power outage, even if you’re not home. Invest in one that can send real-time alerts to your phone or email. Note: Be sure that your internet router is on the UPS otherwise the UPS won’t have internet access to send the alert

Rebooting: What Happens When the Power Comes Back On

• Device Reinitialisation: Many smart devices undergo a brief reboot period when power returns. This means your smart hub, routers and connected gadgets may take several minutes to come back online as they reconnect to your network and the cloud. This is an automatic process, requiring no manual intervention.
• State: Automations and settings may be temporarily out of sync. Some devices might revert to default states or require manual intervention to reset automations.
• False Triggers: Occasionally, devices (like security sensors) may generate false alerts as they detect the power coming back on. 
  
  

Detecting Power Cuts Remotely

For homeowners who are frequently away, knowing that a power cut has occurred might be important. Consider these strategies:

1. UPS Notification Systems: Many UPS units are network-enabled and can alert you via email or SMS when a power outage is detected.
2. Smart Meters and Utility Notifications: Some modern utilities provide outage notifications through dedicated apps or emails. If available in your area, subscribe to these services to keep updated on local power conditions.
3. Remote Monitoring Apps: If your smart system supports it, maintain an app on your mobile device that can show the last known state of your home. This can give you an indication of whether your devices are still online or if they’ve lost connectivity.

Conclusion

Understanding power cuts in a smart home is important for maintaining control, safety and comfort. By knowing which devices will keep running and investing in preventive measures like UPS systems, battery backups and redundant connectivity options, you can minimise disruption during an outage. Being aware of how devices behave when power returns enables you to quickly troubleshoot and re‐synchronise your systems.