Installing a mains powered smoke alarm

The below provides an overview of installation, but please refer to each alarm’s installation manual for tailored guidance.

Which room can I install this smoke alarm?

This smoke alarm can be fitted in living rooms, bedrooms, hallways, landings and dining rooms. If you’re looking for an alarm to detect fire in your kitchen, utility room, attic or garage then check out our range of heat alarms.

How many alarms do I need to install?

The law and recommendations for the number of smoke alarms required are specific to the area you live in and your property type.

For the fastest detection of fire we recommend you install a smoke alarm in the circulation space on each level of the home (hallway and landing) as well as in living spaces and bedrooms. We would install these alongside heat alarms in the kitchen, garage and attic and have the alarms interlinked so that if one alarm sounds, they all sound.

Where should I position the smoke alarm?

If you’re installing the alarm on a ceiling, then it should be at least 300mm from a standard light fitting, and 1500mm from any fluorescent light fitting (with the wiring at least 1000mm away from this fitting). It needs to be installed at least 300mm from the ceiling and walls – if possible, in the centre of the room.

If you’re installing the alarm on a wall then you will need to ensure the alarm is 300mm from the nearest wall, and between 100mm and 300mm below the ceiling.

Smoke alarms should be positioned at no more than 600mm vertically below the highest point in the room.

Installing your alarm

WARNING: Wiring should be installed by a qualified electrician in accordance with BS7671. We advise you to follow the new harmonized cable colour coding as specified in BS7671.

IMPORTANT: The circuit used to power the alarm must be a 24 hour voltage circuit that cannot be turned off by a switch. BS 5839: Part 6 states that: For mains powered alarms, each with an integral standby supply (Grade D), the mains electricity supply should take the form of either a) an independent circuit at the dwelling’s main circuit board, in which case no other electrical equipment should be connected to this circuit (other than a dedicated monitoring device installed to indicate failure of the mains electricity supply to the alarms); or b) a separately electrically protected, regularly used local lighting circuit.

Ensure a permanent connection to the fixed wiring of the building is made in a suitable junction box. 

Remove the terminal block cover.

If trunking is required, snap the break-out tab away from the base plate prior to connection. 

The wiring must be connected to the terminal block as follows:

Live (L) – Connect to the Live in the house wiring.

Neutral (N) – Connect to the Neutral in the house wiring.

Interconnect (I) – If desired, join the Interconnect wire between the alarms.

Use the Earth terminal to safely terminate any copper Earth or green / yellow cable.

WARNING: Mixing the Live and Neutral connections when interconnecting alarms will damage all the alarms. DO NOT use the Earth wire for the interconnect connection.

Either feed the wire through the hole in the base plate or through the YT2 trunking.

1. Line up the alarm with the base plate and gently apply pressure until the alarm clicks into place. Switch on the mains electricity supply.
2. If your alarm is not a sealed back-up battery alarm, then install the batteries following the steps within the manual.
3. Check that the green LED is on and that the red LED is flashing once approximately every 45 seconds. The LEDs are located on the front of the alarm.

After fitting the alarm to the base plate, wait for 5 seconds for the alarm to settle, then test the alarm. See alarm testing.

For guidance on how to hardwire interlink your alarm click here.