1. Introducció
This manual provides essential information for the installation, operation, and maintenance of your First Alert 9120B Hardwired Smoke Alarm. This device is designed to provide early warning of smoke and fire hazards in residential environments.
Les característiques clau inclouen:
- Ionization Sensor: Detects smoke from fast-flaming fires.
- Cablejat amb bateria de reserva: Ensures continuous operation even during power outages using a 9-volt battery.
- Interconnectivitat: Can be linked with compatible BRK or First Alert alarms, causing all connected alarms to sound when one is triggered.
- Alarma de 85 decibels: Provides a loud alert upon smoke detection.
- Botó de prova/silenci: Allows for easy testing of alarm functions and silencing of nuisance alarms.
- Latching Alarm Indicator: Identifies the initiating alarm unit after an event.
- Senyal de final de vida útil: Notifies you when the unit needs replacement.

Image 1.1: First Alert 9120B Hardwired Smoke Alarm. This image shows the front view of the smoke alarm with its test/silence button and speaker grille.
2. Informació de seguretat
Please read and understand all instructions before installing and operating this smoke alarm. Keep this manual for future reference.
- Seguretat elèctrica: Installation involves electrical wiring. Ensure power is turned off at the circuit breaker before beginning installation. If you are unsure about electrical wiring, consult a qualified electrician.
- Wiring Polarity: Confirm correct wiring polarity and secure all wire nut connections. A loose neutral (white wire) connection within the home junction box can cause device malfunction.
- Còpia de seguretat de la bateria: The 9-volt battery backup is crucial for operation during power failures. Ensure a fresh battery is installed and replaced annually.
- Col·locació: Install smoke alarms on every level of your home and in each bedroom for optimal protection.
- Prova: Test the smoke alarm weekly to ensure proper function.
3. Contingut del paquet
El vostre paquet ha de contenir els elements següents:
- First Alert 9120B Hardwired Smoke Alarm Unit
- Suport de muntatge
- Arnès de cablejat
- Bateria de 9 volts
- Manual d'instruccions
Note: This product is typically sold in multi-packs (e.g., 6-pack), meaning you will receive multiple sets of the above items.
4. Configuració i instal·lació
Follow these steps for proper installation of your hardwired smoke alarm:
- Apagueu l'alimentació: Before starting, turn off the power to the circuit where you will be installing the smoke alarm at your main electrical panel.
- Remove Old Alarm (if applicable): If replacing an existing alarm, carefully remove it and its mounting bracket. Disconnect the wiring harness.
- Preparació del cablejat: Connect the new wiring harness to your household wiring. Typically, this involves connecting:
- Black wire (hot) to black wire
- White wire (neutral) to white wire
- Red/Orange wire (interconnect) to red/orange wire (if interconnecting multiple alarms)
- Instal·leu el suport de muntatge: Secure the universal mounting bracket to the electrical junction box using the provided screws.
- Instal·la la bateria: Open the side-load battery compartment and insert the 9-volt battery, observing the correct polarity. Close the compartment.
- Connecteu la unitat d'alarma: Connect the alarm unit to the wiring harness. Align the alarm unit with the mounting bracket and twist clockwise until it locks securely into place.
- Restaura l'alimentació: Turn the power back on at the circuit breaker. The alarm should chirp once and the power indicator light should illuminate.
- Alarma de prova: Press and hold the Test/Silence button until the alarm sounds. This confirms proper operation.
Ubicació recomanada
For optimal safety, follow these placement guidelines:
- Install at least one smoke alarm on every level of your home, including the basement.
- Install a smoke alarm inside every bedroom.
- Install a smoke alarm in the hallway outside of each sleeping area.
- Avoid placing alarms near windows, doors, or forced-air vents where drafts could interfere with smoke detection.
- Keep alarms away from cooking appliances to prevent nuisance alarms.

Image 4.1: Recommended Smoke Alarm Placement. This diagram illustrates ideal locations for smoke alarms, carbon monoxide alarms, and fire extinguishers throughout a typical home, including bedrooms, hallways, living room, kitchen, basement, and garage.
5. Instruccions de funcionament
Prova de l'alarma
Test your smoke alarm weekly to ensure it is functioning correctly:
- Press and hold the Test/Silence button firmly for a few seconds.
- The alarm will sound a loud, pulsating horn. This indicates the electronic circuitry, horn, and battery are working.
- Deixa anar el botó. L'alarma s'aturarà.
Si l'alarma no sona durant la prova, consulteu la secció Resolució de problemes.
Silenciar les alarmes molestes
If a non-emergency situation (e.g., cooking smoke) triggers the alarm, you can temporarily silence it:
- Press the Test/Silence button briefly.
- L'alarma entrarà en un mode de silenci temporal durant aproximadament 10 minuts.
- The alarm will automatically reset after the silence period if the smoke condition has cleared. If smoke is still present, the alarm will reactivate.
Indicadors d'alarma
- Power/Alarm LED: A red LED light indicates the status of the alarm. It flashes periodically during normal operation and rapidly during an alarm condition.
- Latching Alarm: If multiple interconnected alarms are present, the unit that initiated the alarm will have its red LED flash rapidly, while other interconnected alarms will sound but their LEDs will not flash as quickly. This helps identify the source of the alarm.
6. Manteniment
Canvi de bateria
The 9-volt battery should be replaced at least once a year, or immediately when the low battery chirp sounds. The alarm will chirp approximately once every minute to indicate a low battery.
- Turn off power to the alarm at the circuit breaker.
- Gireu l'alarma en sentit antihorari per treure-la del suport de muntatge.
- Obriu el compartiment de la bateria.
- Remove the old 9-volt battery and dispose of it properly.
- Insert a new 9-volt battery, ensuring correct polarity.
- Tanqueu el compartiment de la bateria.
- Reattach the alarm to the mounting bracket by twisting clockwise until secure.
- Restore power at the circuit breaker and test the alarm.
Neteja del teu detector de fum
Clean your smoke alarm at least once a month to remove dust and debris that can interfere with its operation:
- Turn off power to the alarm at the circuit breaker.
- Traieu l'alarma del seu suport de muntatge.
- Feu servir un raspall suau a l'aspiradora per aspirar suaument la coberta i les reixetes de ventilació de l'alarma.
- No pinteu l'alarma. La pintura pot obstruir les obertures i interferir amb la capacitat del sensor per detectar fum.
- Reinstall the alarm, restore power, and test.
Senyal de fi de vida útil
The smoke alarm is designed to provide reliable protection for approximately 10 years. After this period, the unit will emit an end-of-life signal (typically a chirp every 30-40 seconds) to indicate it needs to be replaced. Replace the entire unit immediately upon hearing this signal.
7. Solució De Problemes
| Problema | Causa possible | Solució |
|---|---|---|
| L'alarma no sona durant la prova. | No power, dead battery, or faulty unit. | Check circuit breaker. Replace 9-volt battery. Ensure alarm is properly connected to wiring harness and mounting bracket. If issues persist, replace unit. |
| Alarm chirps once a minute. | Bateria baixa. | Substituïu la pila de 9 volts immediatament. |
| L'alarma sona cada 30-40 segons. | End-of-life signal. | Replace the entire smoke alarm unit. |
| Alarmes molestes (falses alarmes). | Cooking smoke, steam, dust, high humidity, or insect infestation. | Press the Test/Silence button. Ventilate the area. Clean the alarm. Relocate the alarm if it's consistently triggered by non-fire sources. |
| Alarm malfunctions or behaves erratically. | Loose neutral wire connection. | Apagueu l'alimentació a l'interruptor. Check all wire nut connections, especially the white (neutral) wire, in the home junction box to ensure they are secure. If unsure, consult a qualified electrician. |
8. Especificacions
| Característica | Especificació |
|---|---|
| Número de model | 9120B |
| Font d'alimentació | 120V AC Hardwired with 9V Battery Backup |
| Tipus de sensor | Ionització |
| Potència de l'alarma | 85 dB a 10 peus |
| Humitat de funcionament | 10-95% HR (sense condensació) |
| Temperatura de funcionament | De 40 °C (4.4 °F) a 100 °C (37.8 °F) |
| Dimensions (P x A x A) | 1.9" x 5.6" x 5.6" |
| Color | Blanc |
| Material | Plàstic |
| Certificacions | Llistat UL |
9. Garantia i Suport
Informació de la garantia
This First Alert 9120B Smoke Alarm comes with a 10-year limited warranty. For specific terms and conditions, please refer to the warranty documentation included with your product or visit the official First Alert weblloc.
Atenció al client
For technical assistance, troubleshooting, or warranty claims, please contact First Alert customer support. Contact information can typically be found on the product packaging or the official First Alert weblloc.





