First Alert Hardwired Smoke Alarm SMI100-AC — Precision Detection, Interconnectable with Battery Backup

The First Alert SMI100-AC Hardwire Smoke Alarm is a hardwired, interconnect-capable smoke detector with battery backup and Precision Detection sensing to reduce false alarms while delivering fast warning across your home.

Designed to meet updated industry standards, this First Alert hardwire unit replaces many existing plug-in models without rewiring and pairs with other compatible alarms to form a whole-house network. Its Precision Detection sensing technology helps distinguish common cooking smoke from real fire hazards, and the included quick-connect plug makes upgrades quick for homeowners and installers alike.

How does this alarm reduce nuisance alarms from cooking or steam?

The SMI100-AC uses First Alert’s Precision Detection technology to better differentiate between harmless particles—like those produced by cooking—and the types of smoke that indicate a dangerous fire. That reduces unnecessary wake-up or false alarms while maintaining sensitivity for real threats. This balance improves everyday usability, especially in kitchens or near bathrooms where nuisance triggers are more common.

• Advanced sensing algorithm tuned for household particulates
• Meets newer industry standards for reduced nuisance alarms
• Still provides prompt response to fast-burning smoke signatures

What happens when one alarm detects smoke—does the whole house get alerted?

Yes: the SMI100-AC supports interconnect capability so when one compatible unit sounds, all linked alarms in the system will sound too. This early-warning network is especially useful in larger homes or multi-level layouts, ensuring you’re alerted no matter where the fire starts. Interconnect works via the house wiring, and compatible First Alert models can be added to expand coverage.

• Hardwired interconnect links all compatible First Alert alarms
• Audible signal triggers across the connected system
• Ideal for multi-level homes and remote sleeping areas

How simple is installation and what does the battery backup do?

Installation is straightforward: the unit ships with a quick-connect plug that lets you replace many existing hardwired alarms without rewiring the junction box. That saves time for DIYers and professionals. The built-in battery backup keeps the alarm operational during power outages so you still have protection if household power is interrupted.

• Quick Connect Plug included for easy swap-in installation
• No need to rewire most existing alarm bases or junction boxes
• Battery backup maintains operation during blackouts

How will I know which alarm started the alert?

The SMI100-AC includes a visual alarm indicator that identifies the unit that initiated the alarm sequence. This feature helps you locate the source quickly, streamlining response and reducing confusion during an incident. Visual indicators complement the interconnected audible alerts for clearer situational awareness.

• Built-in indicator shows initiating unit
• Works alongside interconnected audible alerts
• Assists in fast location of smoke source for response

Who is this for? The First Alert SMI100-AC is a good fit for homeowners, landlords, and contractors who want an upgraded hardwired smoke alarm with fewer nuisance activations, simple swap-in installation, and whole-home interconnect capability. It’s especially helpful in homes with existing hardwired systems that need modernized protection and in households that want clear, coordinated alerts across multiple rooms and floors.