Mains supply to alarms

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Never put an isolator on a smoke alarm circuit and make sure it’s on a lighting circuit
For what it's worth, I personally agree. I've personally never done the former and have always been the latter,...

However, there are plenty of people around (including a good few who appear 'qualified' to give advice on such matters) who advise an unswitched FCU and a 'dedicated circuit' - I certainly would not personally advise the latter, and see little point (and some potential downsides) of the latter.
 
Isolation and remote silence facilities. BS5389-6
That's all very well, but it doesn't address (and one wouldn't expect it to address) the issue of the isolation that would be required if one needed to work on the fixed wiring supplying the base of an unpluggable alarm (which I have acknowledge to be such a rare event as to not warrant consideration) - so I'm not sure what point you are trying to make.

It is obviously for the 'Wiring Regulations', not a standard about alarms, to indicate what isolation is required in order to work on parts of the fixed wiring of the installation - and, as you know, BS7671 does. If the arms are wired to a lighting circuit, without any intervening switch/isolator, then the whole lighting circuit would have to be de-energised and, in the case of a TT installation with SP MCBs or RCBOs, it would, per BS7671, be necessary to de-energise the entire installation (at least for long enough to open up the CU and physically disconnect L & N of the lighting circuit concerned).

As I've said, I personally see no real need,yet some potential downsides, of fitting an 'isolator' - but that does not alter the fact that a good few people advise or advocate it.
 
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With re-chargeable ones, unless the battery does not live up to its expected life expectancy, that would presumably only happen after a pretty long period without mains power? Anyway, from what you say, it sounds as if, at least with yours,it won't beep with mains failure, provided the battery remains OK?

That would certainly be my personal inclination, but (for whatever reason) I've read quite a lot of contrary opinions about that.

Why is that - because the burglar alarm 'chimes up' in the event of mains failure?
Approximately 3 months without power for the battery to deplete with Ei Electronics/Aico.

The Ei base meets the isolation requirement of BS 5839-6 where powered from a regularly used local lighting circuit.
 
the issue of the isolation that would be required if one needed to work on the fixed wiring
It's the same as for any other circuit.
The presence of connected equipment changes nothing.

If the arms are wired to a lighting circuit, without any intervening switch/isolator, then the whole lighting circuit would have to be de-energised
Yes, it would.
Just like working on any other circuit.
 
As someone said earlier work on them in the daylight, warn the tenants or whoever.
yes, but that was after (and before I repeated it) I had written that I regraded the need for such work as such a once-in-a-blue-moon occurance that it didn't warrant consideration. And when someone wrote what you have just repeated, I confirmed that such was also my view (for the same reason).
You like problems that don't exist....maybe?
On the contrary, I tire of having to spend time thinking about, and ask/write about, 'uncertainties/' due to people raising 'problems' that often don't exist. You don't have to look far at all to see people advising FCUs, key switches or whatever for feeds to alarms, and some of them also advocate are pout into my mind, very often unnecessarily.. In fact, only today the thread here that moved me to start this one saw people talking about such things.
 
The Ei base meets the isolation requirement of BS 5839-6 where powered from a regularly used local lighting circuit.
I've already been through that with flameport.

BS 5839-6 is only interested in isolation of the alarm - and that can be archived by unflagging an Aico alarm from it's base. However, that's totally different from the need for isolation of the circuit if one wants to do work on the circuit - which, in addition to being a matter of common sense, is within the realm of BS 7671.
 
@JohnW2

Just stop procrastinating and fit mains powered inter connected smoke and heat alarms from a lighting circuit
 
It's the same as for any other circuit.
The presence of connected equipment changes nothing.
Yes, it would.
Just like working on any other circuit.
Exactly what I've been saying (x3) - so why are you seemingly arguing?

I merely said that if one wants to work on the fixed wiring feeding an alarm base without having to isolate a lighting circuit to which it was connected, one would have to isolate the entire light circuit if there was no way of isolating just the bits of the circuit feeding the alarms - although I have repeatedly dismissed that a a consideration not worth thinking about.

We see very much the same with the issue of 'fan isolators', with many people suggesting/advising that they should be fit, usually with one of the main reasons being to facilitate working on it without having to disable the lighting circuit it runs from. Again, I regard that as such a rare occurrence as to be essentially a non-reason for fitting an isolator.

You have to remember that, not having been trained as an electrician, I have to rely on people so-trained to advise me or, at least, to confirm (or otherwise!) my own views and opinions about things. When I see quite a lot of people advising/advocating 'isolators' (usually unswitched FCUs) for alarm circuits, even though I don't personally see the need (and can see some downsides), is it not natural and reasonable that I should try to canvas opinion as widely as I can?
 
@JohnW2 Just stop procrastinating and fit mains powered inter connected smoke and heat alarms from a lighting circuit
What on earth are you talking about? Did you not read what I wrote in the very first significant paragraph in the very first post in this thread, namely ...
I will be installing a few (probably Aico) interconnected (hard-wired) mains-powered (and re-chargeable battery backed-up) smoke/heat/CO alarms. .... I am personally no fan of supplying such things from a 'dedicated' circuit, much preferring to power them from the ground floor lighting circuit (whose failure would be rapidly noticed).
 
Regarding wiring of smokes.
To me, you take a 3 core+E from the smoke at the top of the house, run this down to the next floor/smoke etc. until you get to the ground floor smoke. At this last smoke, you can either take a cable to the ground floor light circuit, or run a few more meters into the CU, where you can connect it to the light circuit RCBO, or do whatever you wish with it.

You could have a B6 RCBO where you could connect as many of the following to it as you wish. Smokes, Burglar Alarm, 1 light near CU, door bell
I would want the boiler on it's own, but you could consider that too.
 
What on earth are you talking about? Did you not read what I wrote in the very first significant paragraph in the very first post in this thread, namely ...
So you know what to do and how to do it so what's all this about?
 
Regarding wiring of smokes. To me, you take a 3 core+E from the smoke at the top of the house, run this down to the next floor/smoke etc. until you get to the ground floor smoke. At this last smoke, you can either take a cable to the ground floor light circuit, or run a few more meters into the CU, where you can connect it to the light circuit RCBO, or do whatever you wish with it.
As I've said, that's exactly what i am going to do.

Regarding your "either/or", if (as is probable) I decide not to have an FCU/isolator/whatever (just for the alarms), I will just bring the cable down as far as above the ground floor ceiling, where I'll somehow connect it to the ground floor lighting circuit. However, as you say, if I were persuaded to include an FCU/isolator/whatever for the alarms, I would have to use a bit more cable to get that accessory in an accessible location.

However, as I keep trying to remind people, the ONLY reason I started this thread was to get opinions about whether or not to include some 'means of isolation' (for just the alarms. As I've said repeatedly, my personal inclination is NOT to,but given that a good few people seem to advise/advocate having such a means of isolation,I was trying to get some mor 'expert views' about that question.
You could have a B6 RCBO where you could connect as many of the following to it as you wish. Smokes, Burglar Alarm, 1 light near CU, door bell
As I've said, I have already decided to feed the alarms (as well as possibly other things such as you mention) from the downstairs (6A) lighting circuit.
I would want the boiler on it's own, ...
Why ?
 

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