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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: FIRE on February 18, 2008, 03:33:21 PM
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Could anyone tell me where i can find information on green break glass units - are these essential?
I think they are but am trying to find documentation to take to my employer.
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Try BS 7273 part 4 2007 any device should meet the installation criteria in this BS and conform to the "category of actuation" for the purpose group that the premises concerned currently operates within.
However, they are not essential there are a range of options that you could implement depending the particular circumstances.
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These are used for Means of Escape ie door releases.
If you use the search feature you should be able to find out a bit more about them
one thread that should interest you is
http://www.fire.org.uk/punbb/upload/viewtopic.php?id=1839
So YES they are important!
But what information are you trying to find out?
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My employer is now looking at removing the break glass units and leaving them with just the push to exit button which will fail safe (unlocked) in event of power failure. Is this adequate?
Many request to exit buttons are 'push to make' switches wired across special terminals provided on access controllers for this purpose. The problem with this setup is that it isn't really fail-safe because the disconnection of a wire on this connection does not cause the door to open. i.e the connection breaking or a wire becoming disconnected would stop the switch from working but not cause the lock to release.
The green break glass units should be wired (double-pole) into the feed to the lock so that it can be used to break the electrical feed to the lock, in an emergency, if the request to exit switch fails.
Obviously misuse is a problem, as in this case.
Options that might work are alarmed covers over the green BGU's or an alarm that sounds when the green BGU is operated. Alternatively, where the controlled doors locks are linked into a fire alarm system with an automatic release of the door lock on fire condition, that a fire alarm call point needs to be operated in an emergency on failure of the request to exit button. None of these alternatives avoid potential misuse but at least you know that the security has been breached.
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Many thanks, I'll pass that information on. I think alarmed covers could do the required job so will put that to my employer. Although the possibility of the door failing at the same time someone requires to use it in an emergency is fairly low I still think that measures should be in place .... just in case.
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It is all down to risk assessment and what is required and reasonable in the circumstances ( the BS's are not law). If you are having problems with misuse of a system down to the occupancy or area it is in, then you have to adapt to suit.
A manual override button may be provided, adjacent to the doors secured by electronic locks. but if there is a problem with the occupants ( may be vandalism or mental health issues), provided it is documented in the fire risk assessment, strategy and included in any staff/occupant training and information, you do not require the ‘green’ override box, only the fire alarm call point. Where activation of call points by Occupant/ residents is a problem, consideration should be given to providing measures such as ( in order of increasing technical requirements);
a. Lift flaps that prevent call point activation unless the flap is lifted, which is the least expensive option.
b. Further measures may utilise devices that activate a localized audible warning when a flap is lifted prior to call point activation.
c. In severe cases where the above measures prove insufficient ( usually mental health accomodation), a risk assessment should be undertaken to determine the impact of changing vulnerable break-glass call points to key-operated units that can be activated only by staff with ‘alarm keys’. Where ‘key operated alarm’ systems are provided as item c, included with the normal electronic locking conditions, there must also be the appropropriate procedures and safeguards etc.
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Is it ever 'reasonable' to have no green box override fitted?
Consider an escape route which utilises a neighbouring property at rooftop level of a long terrace with numerous other properties having potential to access the roof.
The door to the neighbour's building is interconnected to the fire alarm of the first building. However if a green box was available adjacent to that door, it would be impossible for security to be maintained as any old Tom, Dick or Hary could enter with ease .
The main occupancy involves sleeping risk with some vulnerable members of the public and, in extreme circumstances, it may not be possible for staff to reach the roof level (ie to operate any key type override)
Therefore is it reasonable just to rely on the AFD system is these circumstances???
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I have come across similar situations and recommended that the magnetic lock is removed and the latching type electronic lock is provided, this would then allow controlled access and egress via a push pad or thumb turn etc, no need for a green box !!
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Speaking personally I have always found latching type electronic locks to be much more problematic than magnetics. Lean on them at the same time as pressing the button and they tend not to let go. On the other hand thumbturns sometimes do not give sufficient security. I think sometimes you have to bite the bullet in the fire risk assessment and to balance security and fire evacuation considerations. Sometimes I have omitted green break glass units and sometimes in hindsight felt a little uneasy about it- in one scheme relying on site security which was later outsourced, or find a lack of diligence over maintenance to the fire alarm system when you were relying on a high level of management as part of the justification. Its not something to do lightly but sometimes omission of the box is essential. In a sterile protected corridor it may be ok, but within a higher risk area or room it most likely is not.
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The last 3 postings have formed the 'thinking' behind a risk assessment, take all this into account and make decision and stand by it, and if need be justify it when called upon to do it. What are we all paid for ?
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On the flip side, why/when is it necessary to link doors into a fire alarm system if there is a means to manually release them via breakglass/thumb turn or similar?
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There has been occasions when the insurance company will not 'pay out' should a main access door has been failed open by an early morning alarm , not a problem if the f/a system signals out ie monitoring station. This may conflict with a risk assessment finding , so clarification needs to be sought.