Battery standby times

[David Rooney]

25.4
"4) For all other Category P systems, the capacity should be sufficient to maintain the system in
operation for at least 24 h longer than the maximum period for which the premises are likely to be
unoccupied or for 72 h in total, whichever is less, after which sufficient capacity should remain to
operate all fire alarm devices for at least 30 min. If the building is likely to be unoccupied for more than
the duration of the standby battery capacity at any time, and there is a facility for transmission of fire
signals to an alarm receiving centre, power supply fault signals should also be automatically
transmitted to the alarm receiving centre, for immediate notification of a keyholder."

So... if i read this right .... and the rest of section 25 regards Cat L systems..... this bit about "24 h longer than the maximum period for which the premises are likely to be unoccupied" is only applicable to Cat P systems.

Where is the bit that says if your average office to L3 is left unattended from Friday to Monday the standby capacity needs to be increased... or did i dream that bit up??

[David Rooney]

This Q came about due to a question raised on one of our BAFE forms compiled by a consultant... thinking about it it can only apply to  Cat P otherwise virtually every office block in the country would need 72 hour standby etc....

I still think however there should be a battery backed buzzer that lasts for maybe 48hours in the event of complete supply failure so that on a Monday morning if the cleaners turn in they are in no doubt there is a problem with the fire panel....

I'm answering my own questions now... think I'm having a Benz moment.....!!   

[Benzerari]

You see Dave, having no one interested in answering the thread, seems like every body is busy with Christmas decorations...

[Benzerari]

Where is the bit that says if your average office to L3 is left unattended from Friday to Monday the standby capacity needs to be increased... or did i dream that bit up??

Hemm..., good thinking, I agree it has to be normally considered in batteries calculations then...!

[Wiz]

David, the 2002 recommendations decided to do away with the previously longer standby duration times for L (and M) systems.

My understanding of the explanation is that it is only necessary for Cat. L fire alarm systems to continue operating during a power cut, and whilst people  are in the building, for only long enough to be able to evacuate them during a fire condition.

It seems BS is not interested in the sort of fault you consider possible, where it could fail in an empty office building on a Friday night and no-one knows about it until the Monday morning. It is assumed that the system healthy indicator is checked on a daily basis during occupation, and I assume BS expects that the building won't be used with a non-operating fire detection and alarm system, or that other measures will be taken to warn occupants of a fire condition.

A longer duration is required of Cat. P systems but still only with a maximum of 72 hours although it is expected that power supply faults would be signalled to the arc.

[Graeme]

can be reduced to 24 hours if signals fault to arc who contacts a keyholder

[David Rooney]

Yes men all this is true and understood.

But people in general only take notice of things that annoy, like wasps, men who wear flat caps while driving and fault buzzers.

How many office staff really look at the fire panel every day to see if a green light is on....??

[Benzerari]

Yes men all this is true and understood.

But people in general only take notice of things that annoy, like wasps, men who wear flat caps while driving and fault buzzers.

How many office staff really look at the fire panel every day to see if a green light is on....??

Very few... 

[Graeme]

about the same number as those who know what the green light means in the first instance..

[Wiz]

Guys, you can either try and understand the recommendations of BS, and when knowing that you comply with them, move on to the next job with a happy heart. Or you can seek out every little deficiency in BS as you see it, and worry yourself to death.

It is not your problem that BS recommends only 24 hour standby in a L3 office building.

It is not your problem that the staff don't check their system healthy indicator every day, even though you previously told them they should.

It is not your problem that the staff don't even know what the system healthy indicator means, even though you've previously told them what it means.

Don't give yourself any more stress, especially at this crazy time of the year. There are many others who will delight in doing it for you, anyway.

If you think BS is aload of b**ll**s, then try and get on the committee and sort it out. Or tell C.T. about it - I bet he is losing no sleep over the things you are worrying about

[Benzerari]

about the same number as those who know what the green light means in the first instance..

  also very few!

[Benzerari]

Guys, you can either try and understand the recommendations of BS, and when knowing that you comply with them, move on to the next job with a happy heart. Or you can seek out every little deficiency in BS as you see it, and worry yourself to death.

It is not your problem that BS recommends only 24 hour standby in a L3 office building.

It is not your problem that the staff don't check their system healthy indicator every day, even though you previously told them they should.

It is not your problem that the staff don't even know what the system healthy indicator means, even though you've previously told them what it means.

Don't give yourself any more stress, especially at this crazy time of the year. There are many others who will delight in doing it for you, anyway.

If you think BS is aload of b**ll**s, then try and get on the committee and sort it out. Or tell C.T. about it - I bet he is losing no sleep over the things you are worrying about

Agreed, but BS is not covering every bits and cases...etc, if setting out extra measures for safety matters that would be better, I wouldn't wait for BS to confirm it! 

But, I agree once again that just applying what BS has recommended, is fully sufficient to cover your back.

[colin todd]

Wiz, Of course i lie awake worrying. It frustrates the hell out of me that the Yanks wont tell us who shot Kennedy. And I still am unclear as to what Billie Joe threw off Tallahatchie bridge.  And in No country for old men, did the geezer kill that girl at the end or did he not. Come to that, what on earth was that film all about. Wiz et al, these are the really important things in life. I proposed the reduction in battery capacity back in 2001, and I have to say, have not given a jot about it since.

[Wiz]

Colin, so I was spot on with my assessment of your probable worry-levels over this issue.

Even though you admit it was all your fault that it was reduced to 24 hours!

Just how blase can you be about matters that so many people hold so dear to their hearts! - Bless 'em.

I sympathise with your worries over other matters.

I can't help you with the Kennedy mysteries, but that geezer in the film did actually kill that girl using his compressed air gun.

With one less thing now to worry about, can you please amend the BS recommendation immediately to now read  'the standby duty of the battery should be 24 hours longer than any circumstance whatsoever that MAY happen whenever (this includes annual staff holidays), and which might possibly affect the charging of the battery, no matter how long that period may be, or indeed, how large a capacity the battery that may be required, in the event, no matter how unlikely, that something might occur plus be able to operate the full alarm load for a further 31 mins (I've added the extra minute as a safety margin, but please adjust this margin as you see fit)

That should do it.

[kurnal]

Wiz, Of course i lie awake worrying. It frustrates the hell out of me that the Yanks wont tell us who shot Kennedy. And I still am unclear as to what Billie Joe threw off Tallahatchie bridge.  .

Now you have gone and done it. All these years I thought that it was Billy Joe and these two were having a heterosexual relationship. No wonder she jumped off the bridge then once she found that she had such complex gender issues. Even the vicar wasn't aware of that.