Smoke Alarm types and connection

Smoke alarm is important component of fire alarm system. And it is part of home security systems.
The smoke detector alarm can be used with fire alarm system or burglar alarm system or independently sound and light alarm on-spot without connection with any alarm systems.
So, there are 4 types of wired smoke alarms. (same as heat detector, CO detector and compound detector). The connection way is different for different types smoke detector alarms.
Correct connection is required to ensure proper work of smoke alarm. Otherwise, danger will be heavier with non-work smoke detector alarm.
We need to buy correct type smoke detector to work with our exist alarm systems. And we need to wire the smoke alarm according to the detector’s manual and alarm receiver’s manual as well.
Below we will introduce these 4 types smoke alarm and connection ways (Smoke alarm type is HST brand as example. The HST brand smoke detector can be bought at Vedard Alarm Store)
Type 1: Independent Smoke Alarm.
The independent smoke detector alarm doesn’t need wire connection. It makes sound and light alert when smoke density reaches to alarm limit. The independent smoke alarm can be battery powered or AC powered with battery power backup.
Type 2: Bus type coded addressable smoke alarm
There are 4 terminals and only terminal 1 and 3 are non-polarity connected to 2-wire bus type fire alarm control panel L1 and L2.

Smoke Alarm non-polarity 2-wire connection
Non-polarity 2-wire Smoke alarm systems

2-wire bus type smoke alarm connection
wire 2-wire bus type smoke alarm

Type 3: Conventional Smoke Alarm
It is 2-wire and non-polarity connection with conventional fire alarm control panel zone+ and zone-. Multiple detectors terminal 2 and 3 are connected to zone- in series. The terminal 2 is connect with terminal 3 of next detector. This connection way will monitor the zone status and report detector error, detector missing to alarm panel. Current limiting EOL resistor is required to wire and the end of the circuit.
Conventional 2-wire Smoke Alarm System wiring
2-wire Smoke alarm wiring with Conventional Fire alarm panel

Type 4: Relay output smoke detector for connection with home alarm system.
It is 4-wire connection. There are 4 terminals on the detector. They are relay output com terminal, relay output NO/NC terminal (default NO), DC power- terminal and DC power+ terminal.
The DC power terminals are connected to AUX of alarm panel and relay outputs are connected to N/O or N/C terminal of the alarm panel. EOL resistor is required to connect to the end of the circuit as well. Please wire this type smoke alarm according to home security alarm panel requirement.
Below is example of home alarm system N/O and N/C wiring requirement.
Smoke detector wiring to N/O or N/C home alarm control panel zone
Home Security Alarm System N/O, N/C contact wiring with smoke detector

Connect 4-wire smoke detector to home security alarm panel
4-wire with relay output Smoke detector connecting with home security alarm panel

Above is example wiring of 4 types wire Smoke detector alarms. Many other brands smoke detector wiring is the same way. But wiring according to manufacturer’s manual is the correct way. For proper work of the smoke detector alarm, please remember to study the smoke detector carefully and install it correctly.

About the Author


Technical support for alarm systems. Help buyer to buying suitable China alarms system and provide China alarm system information, technology advantage. I work as export sales of Vedard China alarms system for home security and business security. Our company cooperate with security service, alarm installer, security engineer. Provide free security solution for hotel security, restaurant security, fire safety solution conventional fire panel and addressable fire panel system with wireless fire alarm system.

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