Wired or radio link smoke detectors

Question

I’m having a loft conversion done and to comply with building control you have either replace all the internal doors to fire doors or have a smoke detector in each room. I’m thinking of going with the smoke detectors in each room. My question is what’s the difference between the hardwired detectors and the radio link ones and also which one can I tap the wire into the existing light fixture and run trunking to the smoke detector.

Karlile · Answer

Hi 
The hard wired detectors are more reliable and are linked to your wiring system 
But your radio linked ones communicate wirelessly 
Smoke detectors need a permanent live so your lights won’t give that

Bakir · Answer

Hi
The smoke alarms need to be interconnected.  if you have carpet you can left the carpet and run the wire.

Doug · Answer

Radio link are battery operated and need to be replaced regularly hard wire is as it would suggest the powered by you electric but do have a battery back up

Scott · Answer

if your in the process of having a loft conversion i suggest you get your electrician to hard wire the smoke alarms into your ring main as they will all be linked and go off together which building control will require and certainly test,radio linked as you call them are ok but not as reliable as hard wired one and the radio linked one are normally used when you or your electrician have forgot to put a hard wired one in a place.

Dawid · Answer

I would suggest to install fire doors and smoke alarms  .  Hard wire smoke alarm requires electrician to install it, is more expensive , but the lifespan  is longer than the battery operated one, which can be installed anywhere , doesn't require electrician and you can get ten year battery sealed version , so you don't need to replace the battery every year .  I would go for battery operated in domestic building for sure and fire doors for my own safety and other people

Rob · Answer

Hardwired and interlinked devices will have a 3 core and earth cable running from each , on their own circuit terminating in the consumer unit . Interlinked meaning if one activates , they all do.

Radio linked is each unit could take its supply from a nearby lighting circuit to power the unit and its separate radio link base . The radio link bases will then talk to each other to all activate in the event of smoke detection.
Regards
Rob

John · Answer

Whilst doing the work hard wire a detector. Ideally they should all be linked, very easy to run off light in any room so visually not overly noticeable. When it comes to fire alarms costs shouldn't matter, but costs should be between 100-150 each unit fitted. Small price to pay in the longterm.

Jeevan · Answer

Hardwired smoke detectors are connected to the mains power and usually interlinked via wiring, while radio-linked detectors communicate wirelessly but still require mains power.

You can tap into the existing lighting circuit for both types, but you must use a permanent live (not switched live) and follow building regulations. Trunking can be used if surface wiring is needed.

For a simpler install with less wiring, radio-linked detectors are a good option. However, hardwired interlinked detectors are generally more reliable.

Rick · Answer

There are now better smoke alarms that can be used wirelessly but each will require hard wiring to the permanent live from either the ceiling rose or elsewhere if the rose is not wired with a 3 wire system (i.e. having a permanent live within the rose).

Nicholas · Answer

The main difference between wired (hardwired) smoke detectors and radio-linked (wireless interlinked) smoke detectors is how they are powered and interconnected:

Hardwired Smoke Detectors
	•	Connected directly to the mains power, usually with a battery backup.
	•	All units are wired together, so when one alarm goes off, they all sound.
	•	More reliable and doesn’t rely on wireless signals.
	•	Requires wiring to be run through the property, which may involve lifting floorboards or running cables in trunking.
	•	Typically, they need to be on a dedicated circuit, but in some cases, you may be allowed to tap into the lighting circuit (check local regulations and building control approval).

Radio-Link (Wireless Interlinked) Smoke Detectors
	•	Battery-powered or mains-powered with a radio signal connecting all the units.
	•	Easier to install since no cables are required between detectors.
	•	Ideal for retrofitting or where running cables is impractical.
	•	Batteries need periodic replacement unless they have long-life sealed units.

Which One Can You Tap into the Light Circuit?
	•	Hardwired smoke detectors can sometimes be connected to the lighting circuit, depending on local regulations. If allowed, they must be permanently live (not switched) and must include a backup battery in case of power failure.
	•	Radio-link detectors don’t require a power connection between units but can be mains-powered, often with a battery backup. These are easier to install without major electrical work.

If you’re already doing a loft conversion, it may be best to go with hardwired smoke detectors as your electrician can incorporate them into the build. However, if retrofitting to an existing home without running new cables, radio-linked detectors are a more practical option.

Wired or radio link smoke detectors

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