Smokes

[APSH]

Hi guys Just a quick one. Got a job soon to wire smokes in a 3 bed house. I usually wire from spare way in consumer unit and on to each unit, but this time as there is no access back to board and no spare way, I was going to use Aico Radiolink, but have not used these before and have read that they need isolation to the units? I was led to believe that you just wire from locally used light to each smoke alarm? but have recently read that you are needed to provide isolation to the unit? just wondering if someone can lend some guidance on this?

thanks For your Help In advance

 

[Plonker 3]

Manufacturers instructions should be followed as they will over rule any regulation. The feed can be from any circuit although a lighting circuit is usually used as they are normally ceiling mounted. If it is a existing installation and not a new build you could always mount the isolation point on the ceiling close to the smoke detector.

 

[Rockingit]

Depends on what level of isolation is being referred to, really. If wired to the lights then isolate at the DB, if local isolation is specd (and I can't think why it would be) then you'll be fitting fsu's in inventive places

 

[swparksey]

Had a quick look on their website and no mention of additional isolation just wire off lighting.

How do I wire (RadioLINK)? Aico - Fire & CO Detection & Fire Protection Specialist

When they refer to isolation they probably mean the CB for the lighting, for maintenance etc.

 

[jase]

I have heard of when you wire from DB to lighting circuit and then from lighting circuit to smokes of people putting FCU in btween lighting circuit and smoke circuit, this allows smoke circuit to be isolated whilst still allowing the lights to be on, cant think of any regs on it, maybe its in BS5389?

 

[swparksey]

I have heard of when you wire from DB to lighting circuit and then from lighting circuit to smokes of people putting FCU in btween lighting circuit and smoke circuit, this allows smoke circuit to be isolated whilst still allowing the lights to be on, cant think of any regs on it, maybe its in BS5389?

Not an idea I would be a fan of, as the home owner could simply remove the battery and fuse when he gets that annoying beeping
I don't think their is a reg that would preclude it.

 

[telectrix]

IMO, fitting a FCU to isolate the detectors from the lighting circuit is pointless. the detector can be isolated for maintenance just by pulling it off it's base. what maintenance can be carried out with the detector still in place? none!

 

[brman]

IMO, fitting a FCU to isolate the detectors from the lighting circuit is pointless. the detector can be isolated for maintenance just by pulling it off it's base. what maintenance can be carried out with the detector still in place? none!

there was another thread here recently about aico alarms and this was the statement from aico themselves I believe. i.e. isolation can be done buy sliding the unit from it's base, no other isolator is needed.

 

[telectrix]

exactly.

 

[Farmelectrics]

new builds i would have them on there own circut existing builds just come of lighting circut not aware of non compliance with bs7671

 

[APSH]

Hi guys, Thanks for the advice. I did think you could come off light straight to smoke, but looked in one of the guides and saw a note on this and it threw me a bit. Anyway Thanks for all the help.

Andy

 

[telectrix]

new builds i would have them on there own circut existing builds just come of lighting circut not aware of non compliance with bs7671

i never put smokes on their own circuit. too easy for mr. numpty to turn off the MCB when mrs. numpty burns the toast.

 

[myristate]

Under BS5839-part 6 your dwelling would be classed as a "Grade D" system.

There is a conflict that some people come across that is BS 5839-1 says that for reasons of electrical safety, the mains supply to all parts of the fire alarm system should not be supplied via an isolating protective device (such as a circuit-breaker), BS 5839-6 on the other hand, says that the circuit serving the fire detection and alarm system should preferably not be protected by any residual current device (RCD). Which is right?

Dedicated circuits are required for Grades A, Band C systems, and BS5839- 1 systems, so the use of an RCD is not allowed. With the introduction of the 17th Edition of BS 7671 lEE Wiring Regulations, all new dwellings may be required to have RCD protection. Where "Grade D" smoke alarms are supplied from a frequently used lighting circuit, it is likely that, by default, this will be provided with an RCD unit. Grade E systems cannot be connection via an RCD. Now new and altered domestic installations, which include fire systems, will be required to have 30mA RCD protection throughout.

On a side note "Grade C, D, E" do not require fire resistance cable for them to be wired in these grades of system need only to be provided with general cables such as T&E, which are suitable for the voltage and current being used by the system. Only Grades A and B require fire-resistant cables.

So to sum up, you can wire it in T&E and because of the type of building it does not require local isolation like a spur.