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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: Argyle on December 06, 2012, 01:43:25 PM
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I know what everyone will say -but once and for-all can someone clarify for me - if I have for example an office block with doors on the escape route fitted with electromagmentic locks . if the lock is fitted to unlock on the fire alarm, unlock on power failure , has a push button on the escape side for general use ie to unlock the door do I still need the green box ( single action / double pole) . Yes on No answers please.
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YES, if following the recommendations of BS7273-4.
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But no if you apply a common sense assessment approach ;) what is the likelyhood of the door not opening and why would it not?
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Also yes if wishing to comply with Approved Document B.
The DCLG guides are a bit more woolly - they mention all three but the way they state them you could interpret it as being you only need one or more fail-safes as oppose to all three.
If you can justify why you don't need green break glasses then so be it, but usually this is when the risk of having them outweighs the risk from not (secure accommodation & similar). Just because the installer forgot or couldn't be bothered, or they ruin the decor (reasons encountered in the past) wouldn't cut it.
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..... what is the likelyhood of the door not opening and why would it not?
Failure of the power supply or a fail-safe electromagnetic release, in such a way that the door is unable to be used to escape, is unlikely. Or, at least, in any way that the inclusion of an EDR switch (green box) would have any benefit.
The Request-To-Exit switch can be a real problem. If it is wired as a simple push-to-break switch directly to the power energising the lock, then you have the likelihood of the switch itself failing in some way affecting the door lock releasing. I don't believe there is any minimum manufacturing quality standard for a RTE switch. If it is wired, instead, to some other door control equipment (such as keypad and/or proximity reader type control) it may NOT be wired in a fail-safe manner. (it all depends on the particular set-up of the 'other door control equipment' wiring needs). Even if it is wired as a simple push-to-break switch then really it should be wired to break both power feed legs (like an EDR switch and for the same reasons) and, it might be argued, that a simple unobtrusive RTE switch may not be easily identifiable in a panic situation.
The link to the fire alarm to release the door is fraught with potential problems. BS7273-4 has tried to address these and has created a plethora of recommendations which are difficult to understand and, in my opinion, creating a cost implication that far outweighs the benefits when an EDR is correctly installed.
The green-box EDR is, in my opinion, much more important than a link to the fire alarm system, which can be difficult or expensive to achieve correctly.
In my opinion, not only should correctly installed green box EDRs always be used, they should maybe be made mechanically more reliable (if possible) and easier to identify as to their purpose in an emergency. They are probably the most important piece of equipment in the whole electromagnetic door release set-up.
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Gents
thanks for you replies - what I expected really -just wanted some reassurance. On the point of the RTE switch . I have a large set of gates to the front of my house . With an electromagnetic lock. Sereral months ago now ( on a wet an windy day) when I got home from work my wife was not a happy bunny in that when she left to go to work in the morning ( I had already gone by then ) she went to the gate pushed the button and nothing , she was not to pleased to climb over a 7 foot gate in higheels and skirt to the mirth of passers-by. To compound the problem she had to do the reverse on getting back home. Luckly we did have a green box fitted with all of the other electronic for the gate under the stairs - she was obviously not listening when i told her about it two years previous. So they do fail .
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...So they do fail .
...wives or RTE switches?
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Forgive the ignorance Wiz but been out the loop for a while, EDR abbreviation for?
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Emergency Door Release
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All I need to say is "New Look" Oxford Street.
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For more info on new look regarding green boxes check out http://www.bailii.org/ew/cases/EWCA/Crim/2010/1268.html item 16
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All I need to say is "New Look" Oxford Street.
Does it state that green box overides should have been provided?? (item 16)
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No, but New Look is now case law and barristers will draw judgements from the details and will utilise BS's as the standard. Therefore, the 3 parts of BS 7273-4 will always apply.
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Jokar - so as to be clear can you specifiy the 3 parts . I would quote 8.2 and 12.2
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No, but New Look is now case law and barristers will draw judgements from the details and will utilise BS's as the standard. Therefore, the 3 parts of BS 7273-4 will always apply.
"always apply" cant say they will always apply. unlikely they wouldnt but to say always is not strictly true.
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so are people saying that if it opens on actuation of fire alarm, fails safe to open in the event of power failure, there's a double pole red call point next to the fire exit door(so if the fire alarm fails it will still open)...it still needs a green box?
I wouldn't ask for it
edit...maybe I read the op's question wrong
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so are people saying that if it opens on actuation of fire alarm, fails safe to open in the event of power failure, there's a double pole red call point next to the fire exit door(so if the fire alarm fails it will still open)...it still needs a green box?
I wouldn't ask for it
edit...maybe I read the op's question wrong
Lingmoor, in a typical set-up, the operation of a fire alarm call point sends a signal back to the fire alarm control panel, the fire alarm control panel then sends a signal back to a relay which disconnects the power to a electromagnetic door lock causing the door lock to release. None of this is fail-safe, and can't easily be made fail-safe. the typical fire alarm call point has no direct interconnection with the electromagnetic door lock.
If you rely purely on the operation of the fire alarm system to release a locked door then you have a set-up with many potential failure points and no way of releasing the door in an emergency if the set-up does fail.
A correctly installed EDR switch (green box) is about as good as you can get in providing a system where you can always effect escape through an electromagnetically locked door (fitted with fail-safe lock).
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Wiz
yes I mis-read the OP's post
I was talking about double pole fire alarm call points that have a direct connection with the electromagnet..same as a green box
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Wiz
yes I mis-read the OP's post
I was talking about double pole fire alarm call points that have a direct connection with the electromagnet..same as a green box
In my 30+ years in the business, I have not seen an installation using a fire alarm call point as also an Emergency Door Release switch. It sounds like it might be a good idea although the BS don't recognise such a set up. The switching of the the electromagnetic door lock would have to be double-pole to suit current BS, so that means the 'combined' switch would have to be triple-pole (at least) to also accommodate the signalling to the fire alarm system. And I wonder if there would be any confusion regarding people expecting to see a 'green box' EDR and only finding a fire alarm mcp?
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Morning all and a great weekend for Irish rugby it has been. 100% success rate for the four provinces.
Anyway, following a comment in an engineers report that the operation of a green box should actuate the fire warning system I have looked through BS7273 Pt4 and take from what I have read, or not read, what I have always assumed, that this is not the case.
Am I still correct?
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You are right. Have never heard of an green EDR activating the fire alarm system. Ask him where he accessed his information.
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You are right. Have never heard of an green EDR activating the fire alarm system. Ask him where he accessed his information.
Knowing the outfit who reported it Paul I would think his information came from up the U bend. This "Registered" outfit wired a fire alarm system with flat T&E.
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Well there you are NT....say no more
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It's an emergency door release not a fire door release, you might need to use the exit when sounding the alarm is not required or even counter productive - perhaps they were getting mixed up and meant that a fire warning system should release the door.
They will be saying next that a fire alarm break glass should set off all the sprinklers (because that's what happens on TV....) ;D
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perhaps they were getting mixed up and meant that a fire warning system should release the door.
No. It was the green box.