'Isolator'/switch for smoke etc. alarms?

[JohnW2]

As often discussed, although most mains-powered smoke/heat etc. alarms give an indication of power failure, I personally favour running them off a downstairs lighting circuit (rather than a 'dedicated' circuit) so that failure of the circuit concerned is rapidly noticed.

As also often discussed, it's generally considered undesirable that alarms be fed through a switch or FCU, since the alarms are then too easily 'disabled', deliberately or even 'by accident'.

However, since there's something to be said for being able to 'isolate' the alarms (to work on them) without losing lighting, what do people think about feeding them through a key-operated switch or suchlike? That would certainly prevent accidental operation, and would do at least something to deter deliberate operation.

Kind Regards, John

 

[Harry Bloomfield]

As often discussed, although most mains-powered smoke/heat etc. alarms give an indication of power failure, I personally favour running them off a downstairs lighting circuit (rather than a 'dedicated' circuit) so that failure of the circuit concerned is rapidly noticed.

Don't all/most fire alarms, indicate they have lost mains power by bleeping regularly, anyway? Mine are on a dedicated MCB.

 

[JohnW2]

Don't all/most fire alarms, indicate they have lost mains power by bleeping regularly, anyway?

Maybe you didn't read the first sentence of my my post ...

As often discussed, although most mains-powered smoke/heat etc. alarms give an indication of power failure, I personally favour running them off a downstairs lighting circuit (rather than a 'dedicated' circuit) so that failure of the circuit concerned is rapidly noticed.

Mine are on a dedicated MCB.

As are many others but, as I said, I personally favour using a downstairs lighting circuit. Some occupants of the house may not understand the reason for "bleeping regularly" alarms (maybe thinking it's due to an alarm malfunction, or even smoke which they can't find), but they won't miss a lost lighting circuit for long!

Whatever, my question related to the situation when the alarms are powered from a lighting circuity, and it's whether or not people feel that a key-operated switch/isolator would then be reasonable is what I'd be interested to know.

 

[jj4091]

Why would you want to work on a smoke alarm. Surely you would just isolate the lighting circuit and replace the whole thing. I wouldn't think you would need to have it on a seperate circuit. Unless it was buried in a dark understairs cupboard and even then you could use a torch.
Personally ours are the same as yours.

 

[AndyPRK]

How often so you need to do maintenance on it ? Once every 10 years!

Far more likely to be changing a light fixture

 

[JohnW2]

Why would you want to work on a smoke alarm.

The same sorts of reason why one would work on the wiring of any other circuit in an installation - admittedly only a rare activity (for any circuit').

Surely you would just isolate the lighting circuit and replace the whole thing.

What 'whole thing'?

I wouldn't think you would need to have it on a seperate circuit.

Many people advocate that, and I think that manufacturers and regulations/standards actually suggest it. I suspect their reason is that a dedicated circuit is less likely to fail (not much to cause it to fail).

 

[JohnW2]

How often so you need to do maintenance on it ? Once every 10 years! .... Far more likely to be changing a light fixture

All true .... but similar is essentially true of many of the things that people feel 'need'. or would 'benefit from', isolators!

 

[Murdochcat]

Always on the upstairs lighting circuit and as I always fitted Aico it is simple to remove them from their bases.

Never give people an easy way to isolate life saving alarms

 

[Harry Bloomfield]

As are many others but, as I said, I personally favour using a downstairs lighting circuit. Some occupants of the house may not understand the reason for "bleeping regularly" alarms (maybe thinking it's due to an alarm malfunction, or even smoke which they can't find), but they won't miss a lost lighting circuit for long!

Increasing the chance of the fire alarm supply, being lost, if the lighting circuit trips due to fault, and it not being able to be restored.

 

[nero44]

but for that most of them have battery backup no? My Aico continuously run if the lighting circuit is off. No beeping, just the LED indicates that it's on battery rather than mains supply.

Never give people an easy way to isolate life saving alarms

would agree to that wholeheartedly

 

[Harry Bloomfield]

No beeping, just the LED indicates that it's on battery rather than mains supply.

Who regularly checks that the LED is lit? Not me, the mains supply could be missing for months, before I would notice. The bleep, every so often, is quick to be noticed.

 

[ebee]

I think as John said in the OP would be the best answer.
Whilst I`ve never considered having an isolator for them I can see the merits so a yes from me.
I have done simlar with some emerency lighting - install the first emergency light on a radial after the last lighting of the loop of the lighting circuit - therefore any break anywhere on that lighting circuit (in its easiest form) causes avtivation of all the ELs. The isolator then provides a means of testing and a means of safe working on those units.

If you are installing a new lighting circuit plus an emergency lighting circuit at the same time it is easy to run it as a loop outwards and a loop inwards at the same time and it is really onle one radial at twice length.

 

[Harry Bloomfield]

I have done simlar with some emerency lighting - install the first emergency light on a radial after the last lighting of the loop of the lighting circuit - therefore any break anywhere on that lighting circuit (in its easiest form) causes avtivation of all the ELs. The isolator then provides a means of testing and a means of safe working on those units.

Emergency lights, are entirely different to fire alarm systems - they need to come on automatically, if the lighting circuit, for any reason, fails.

If a fire alarm system is the only circuit, on an MCB/RCBO, then IMHO - that provides all the isolation needed. Why would a key switch on similar be needed, in addition? I do agree, that there needs to be better warning, than an LED going out, should the mains fail, or someone trips the circuit.

 

[jj4091]

The same sorts of reason why one would work on the wiring of any other circuit in an installation - admittedly only a rare activity (for any circuit').

What 'whole thing'

I thought you were asking specifally about smoke alarms. Which as I said could be simply isolated bt the lighting protective device.

The whole smoke alarm. I wouldn't have thought it was worthwhile trying to repair one. So the lighting circuit is not going to be isolated for long while it's changed.

 

[Harry Bloomfield]

The whole smoke alarm. I wouldn't have thought it was worthwhile trying to repair one. So the lighting circuit is not going to be isolated for long while it's changed.

Not much fun, working after dark, with no lighting available, and could be quite dangerous.