Green break-glass boxes

[Wiz]

Your views please. Do you consider it necessary to link an electronic lock, on a final exit door, to the fire alarm system if its fitted with a green break glass box. Some varying views here at my neck of the woods.  

Wow! This has got technical....

Returning to the original question, I think AnthonyB and Marty, early on, gave the ideal answer.  But I've been in buildings that are huge (from Cathedrals to big sheds (and I mean big)) and to link every electronically secured door back to the alarm panel would mean literally miles of very expensive cabling.  In such cases, is it not agreed that a reliable one of these



is satisfactory as the sole means for ensuring that the door is always available for escape.....provided it also has one of these



Stu

Stu, You can't have understood my answer. I apologise that it isn't clearer.

There is no question that the equipment shown in your pictures is what might be required for a system. However, It is how you wire them up that is the important part! You could install the equipment shown in your pictures in a manner that would mean that the system didn't fail-safe if affected by a fault. BS7273-4 provides recommendations to reduce the liklihood of faults causing the door(s) to remain locked in an emergency.

BS isn't interested in the difficulties you might have in complying with it because of cost and/or effort in doing so just because your site is a cathedral or a big shed.

Your post seems to be more in-line with the original question (not FSO's off-shoot) and it would be interesting to find out why exactly 'it is now commonplace to find an interface between the fire alarm system and electrical release mechanisms', when these 'mechanisms' are doors.

My last answer was given in response FSO to a diiferent question from the original. It was answering the question as to why you can't rely on just a RTE switch and fire alarm link. i.e without any EDR.

You also have to understand two things; One, that there is often much more than first meets the eye. Just seeing a RTE switch and EDR switch installed doesn't mean that the system is fail-safe. Two, that on this forum you get both personal opinions of what someone thinks is sufficient, and also details of what the authorative standards and guidance recommend. It is your own choice to decide which you follow.

However, some people also want to understand the reasons behind what the recommendations are asking for or why it is common practice to do somethin. I considered FSO's question to be this sort. I therefore answered FSO's question in as much depth as my knowledge and experience extended to. I apologise if it was too technical but I hope I covered every angle for FSO

Most importantly please note that the original question posted has not yet been answered by anyone. In other words ,the question asked was, ' If an EDR (green box) is installed (lets assume it is installed properly to BS7273-4) then why does the release system need to be linked to the fire alarm? The underlying question being that, fire condition or not, anyone needing to exit that door in an emergency could always use the EDR. Seems a good question to me.

I subsequently asked if anyone knew of any authorative document that recommended the linking of door release mechanisms to the fire alarm system. There has been no answer.

[Wiz]

SEE WIZZY, you CAN understand BS 7273-4 just fine. And goddam it now that you do you like it so much that you want to extend its scope beyond that for which the BS 7273 suite was first invented. How cool is that. For your next task, I want to you to work on explaining Ohms Law to those amongst our enforcing authority chums who are arrogant enough to think if they cant understand it, it is not worthy of their attention. Use the analogy of water going through pipes cos they can relate to that.

Colin, they say that sarcasm is the lowest form of wit, and whilst I accept that I have stooped somewhat low myself on occasions, you must be slithering around Firenet on your belly for much of the time!

I have never said that I understood none of BS7273-4, only that there is too much in it that is difficult to understand. My opinion is that it is a poorly written BS. I am entitled to my opinion and I know others share it. I have much more experience and knowledge of fire alarm systems and of understanding various guidance documents than you seem to believe, so I think my opinions are valid.

On this forum we have tried to get some discussion going in the hope that those of us who are interested in being able to comply with BS7273-4, find ways of doing so. This is in the hope of making the world a safer place, which I'm sure is also the intention of this BS. We had hoped to to receive some useful guidance from those who may have been involved in the production of this BS, but that has not materialised.

I have been unable to convince any of my colleagues to share the cost of the half-day BS7273-4 'enlightenment' course, not because we don't need it, but because we wonder why we should pay to be lectured in a condescending manner, when we can get that for free at home!

You previously said that you were bored with the subject of our complaints about BS7273-4, but you have continued to make sniping comments. Please, either give me some useful input to help me understand the BS, or just don't bother replying to my posts. I rarely find your sarcasm of anyone's posts on Firenet to have much humour.

[AnthonyB]

Phoenix, if the route doesn't require anti panic fastenings and is used by persons familiar with the building who can be instructed about the fastenings, then as long as it's wired locally correctly as Wiz details then there may be grounds to accept it without a link to fire alarm systems.

As for authoritative documents requiring a fire alarm link to mag locks there are several in the form of Guidance Notes to the Fire Precautions Act issued by many brigades which set the minimum specification they would accept for mag locks in certified premises. Although the FP Act is gone a few brigades have retained the notes for responsible persons under the FSO to refer to.

This is, I think, the origin of the practice.

[Wiz]

Phoenix, if the route doesn't require anti panic fastenings and is used by persons familiar with the building who can be instructed about the fastenings, then as long as it's wired locally correctly as Wiz details then there may be grounds to accept it without a link to fire alarm systems.

As for authoritative documents requiring a fire alarm link to mag locks there are several in the form of Guidance Notes to the Fire Precautions Act issued by many brigades which set the minimum specification they would accept for mag locks in certified premises. Although the FP Act is gone a few brigades have retained the notes for responsible persons under the FSO to refer to.

This is, I think, the origin of the practice.

That makes sense AnthonyB, and I suppose that now the FP Act doesn't apply, it is now all down to a risk assessment.

What do the guys doing Risk Assessments and the Fire guys doing inspections think about not linking emergency release mechanisms (only talking about doors held normally locked here) to the fire alarm system, as long as there is a correctly (BS7273-4) powered, wired and signed EDR (green box) appropriately positioned beside the normally locked door?

[FSO]

However, some people also want to understand the reasons behind what the recommendations are asking for or why it is common practice to do somethin. I considered FSO's question to be this sort. I therefore answered FSO's question in as much depth as my knowledge and experience extended to. I apologise if it was too technical but I hope I covered every angle for FSO

Yes thank you Wiz.

[Davo]

Gents

In MHO Anthony B got it spot on, if people don't know what it is they ain't gonna give it a bash


Also, please advise how I would know how it is wired when the wiring is not visible
We have over 200 of them, some with thumb twists on the doors, some without



davo

back two days and already missing me Amstel varellio megalo

[Phoenix]

What do the guys doing Risk Assessments and the Fire guys doing inspections think about not linking emergency release mechanisms (only talking about doors held normally locked here) to the fire alarm system, as long as there is a correctly (BS7273-4) powered, wired and signed EDR (green box) appropriately positioned beside the normally locked door?

Well, a lot of these guys think it's just fine.  But, just for argument's sake I'd like to hear Marty's opinion.

I think there's good answers to the original question embedded here and there in this thread.

Thanks for your elucidation, Wiz.  I do have a further question though.  You say this:

My last answer was given in response FSO to a diiferent question from the original. It was answering the question as to why you can't rely on just a RTE switch and fire alarm link. i.e without any EDR.

But I, and excuse my ineffective gleaning powers if you have made this explicitly clear earlier, am left wondering the following:

1.  Are you saying that every electronically secured fire exit is unsatisfactory if it only has a red fire alarm call point next to it (as well as the obligatory RTE button, of course) to release the door?  i.e. Should it also have a green emergency door release box?

2.  If so, could you, for my simple brain, explain why?

Ta

Stu

[Wiz]

What do the guys doing Risk Assessments and the Fire guys doing inspections think about not linking emergency release mechanisms (only talking about doors held normally locked here) to the fire alarm system, as long as there is a correctly (BS7273-4) powered, wired and signed EDR (green box) appropriately positioned beside the normally locked door?

Well, a lot of these guys think it's just fine.  But, just for argument's sake I'd like to hear Marty's opinion.

I think there's good answers to the original question embedded here and there in this thread.

Thanks for your elucidation, Wiz.  I do have a further question though.  You say this:

My last answer was given in response FSO to a diiferent question from the original. It was answering the question as to why you can't rely on just a RTE switch and fire alarm link. i.e without any EDR.

But I, and excuse my ineffective gleaning powers if you have made this explicitly clear earlier, am left wondering the following:

1.  Are you saying that every electronically secured fire exit is unsatisfactory if it only has a red fire alarm call point next to it (as well as the obligatory RTE button, of course) to release the door?  i.e. Should it also have a green emergency door release box?

2.  If so, could you, for my simple brain, explain why?

Ta

Stu

Stu, I am always happy to provide my understanding of these things. I think it is what Firenet should be used for i.e an exchange of information and opinions between people with a common interest.

1) The simple answer to your question is yes if you want to comply with BS7273-4, and, in fact, the practice that was most acceptable to those who know about these sort of systems even before that BS existed.

2) An electronically secured fire exit is probably the most dangerous (for life safety) of all types of release mechanism for doors. If the door can't be opened in an emergency people can become trapped.
BS7273-4 recommends that all such doors always have an Emergency Door Release (green box) (other than on doors in buildings where people are being lawfully detained -although these might need alternative precautions) The right type of EDR, and correctly wired, is meant to provide the best protection against failures in any of the other provided release mechanisms i.e link to fire alarm or Request To Exit switch.
Both the link to the fire alarm and the RTE switch have numerous possibilities for failure. The fire alarm link because it is so complicated and the RTE switch because it can wired in ways that are not fail-safe and also that constant normal use might make it more likely to fail.
The BS7273-4 recommendations for the EDR provide the best 'fail-safe' back-up for the failure of the other methods. If all else fails, the EDR is a switch wired in both legs of the power feed to the lock and is sited close, both physically and electrically, to the lock.

The above is the general background to my interpretation of the thinking behind the recommendations, and I am hoping that is what you want. I have explained the technical bits about the potential problems with the RTE switch in my previous answer. I hope that was sufficient. If you want to know about the potential problems with the fire alarm link, it would take me some hours to explain!

All of the above is my interpretation of the thinking behind the BS recommendations. It doesn't mean to say that I agree with them, or disagree with them, only that the above is my understanding of what the BS is trying to achieve and why.

[Phoenix]

Thanks Wiz.  Very interesting.

Up until about ten or twelve years ago, before the emergence of these green boxes, all we had (and what we used to ask for) was a break glass fire alarm call point next to the door and the door interfaced with the alarm.  We were quite happy with that and there are still thousands of doors like that around the country.

Fire alarms are interfaced with all sorts of life safety mechanisms, for example:

Lifts
Dampers
Escalators
Automatic opening vents
Pressure differential systems
Sprinkler pre-activation valves
Hold open devices on fire doors
Car park barriers
Fire shutters
Fire curtains
Entire smoke control systems in atria
etc

These are pretty important life safety interfaces.  Some have manual over-rides, but these over-rides are generally for more complex reasons than being there just in case the interface fails.

In each case where such systems are interfaced it is assumed that the interface will work as planned.  It is assumed that correct servicing, testing, fault correction and general maintenance will ensure that these interfaces perform as required when required. 

I know you're just commenting on the standard but why do you think 7273-4 singles out electronic security locks to have this additional piece of equipment?

Seems over the top to me.  I can get very cynical about such recommendations, especially when the industry has been involved in the development of the standard.

Stu

[Wiz]

Stu, I don't disagree with some of your opinions. Sometimes belt and braces are not enough for some people, for them it has to be two belts and two braces, and others at least three sets! Where do you stop?

I've often said to people preaching about how they've made something fail-safe, that if they show me their 'fail-safe' circuit, I'll point out where it doesn't actually 'fail-safe'. Total 'Fail-safe is an impossibility!

I am not the biggest supporter of BS but for reasons other than those you mention. I disagree with you, for example, about the necessity of involving equipment manufacturers in the production of BSs. I think it is an imperitive.

Also, I believe absolutely that BS7273-4 has been written with the best intentions to make systems more reliable.

The people who devised the BS were obviously concerned about people being trapped in a burning building by not being able to use a locked door that has not released, and have tried to provide a solution by use of an EDR. I presume, the locked door scenario risk is seen to be higher than most, if not all, of the other systems you mention.

You would need to talk to these people about the reality of this risk, and if their methods of reducing it are the most appropriate. Mr Todd has made mention of these risks in various previous postings on Firenet.

[CivvyFSO]

I shall take the simpleton's view of it all. Ignoring any failsafe devices, any british standards, any electrical detail... What you want to avoid is a system where a failure of the fire alarm system also ensures that all the doors in the building remain locked at the time when they are most needed.

[David Rooney]

My similar simple view...

All electronically locked doors on fire escapes should generally release automatically with the fire alarm simply because it saves people in a panic situation looking for a release mechanism be it handle/thumbkey/pushbar or whatever and may prevent a pile up of bodies crushed against a door preventing the one up against the door from using the mechanism even if he could find it.

In addition, if the door has a single action mechanical release etc that withdraws the latchbolt from the keep (like a pushbar/thumbkey arrangement) then no other form of release ("green breakglass") is necessary.

But all electronically locked doors on fire escapes without a mechanical release mechanism that rely on electrical connections to affect the release of the lock (such as mag locks/solenoids etc) must have a reliable absolute method of cutting power to the lock ie. double pole green breakglass directly in line with the lock.

[Phoenix]

Thanks again for your comments Wiz.

I am not the biggest supporter of BS but for reasons other than those you mention. I disagree with you, for example, about the necessity of involving equipment manufacturers in the production of BSs. I think it is an imperitive.

You don't disagree with me here actually, because I also know that it is essential that industry practitioners are involved in the setting of standards.  I just know that committees are  prone to human frailties, particularly the frailties that arise when some characters are more vociferous than others.  This is just the way of the world, and there is nothing that can be done about it.  Catch 22.  I accept.

But this realisation and acceptance is important because it tempers my/your/one's faith in the standards.  I get the feeling that you're with me on this point, Wiz, and I hope that most others in this field feel the same.

What you want to avoid is a system where a failure of the fire alarm system also ensures that all the doors in the building remain locked at the time when they are most needed.

This is true, but a properly maintained and tested alarm system shouldn't fail.  In a shopping mall, it is of paramount importance that when the fire alarm actuates, the correct channelling screens drop, the air inlet ventilators open, the appropriate fans or natural roof ventilators operate, appropriate containment screens drop, dampers and shutters operate as required, HVAC system shut down or adapt as required and so on.  All this is reliant on the alarm system operating correctly and we trust that this will happen.  All I'm saying is, why can't we have the same faith when we're considering doors linked to the fire alarm?

As a pragmatist, I do have an answer to my own question.  I'd just like to hear someone else's opinion.

Stu

[Allen Higginson]

Thanks again for your comments Wiz.

I am not the biggest supporter of BS but for reasons other than those you mention. I disagree with you, for example, about the necessity of involving equipment manufacturers in the production of BSs. I think it is an imperitive.

You don't disagree with me here actually, because I also know that it is essential that industry practitioners are involved in the setting of standards.  I just know that committees are  prone to human frailties, particularly the frailties that arise when some characters are more vociferous than others.  This is just the way of the world, and there is nothing that can be done about it.  Catch 22.  I accept.

But this realisation and acceptance is important because it tempers my/your/one's faith in the standards.  I get the feeling that you're with me on this point, Wiz, and I hope that most others in this field feel the same.

What you want to avoid is a system where a failure of the fire alarm system also ensures that all the doors in the building remain locked at the time when they are most needed.

This is true, but a properly maintained and tested alarm system shouldn't fail.  In a shopping mall, it is of paramount importance that when the fire alarm actuates, the correct channelling screens drop, the air inlet ventilators open, the appropriate fans or natural roof ventilators operate, appropriate containment screens drop, dampers and shutters operate as required, HVAC system shut down or adapt as required and so on.  All this is reliant on the alarm system operating correctly and we trust that this will happen.  All I'm saying is, why can't we have the same faith when we're considering doors linked to the fire alarm?

As a pragmatist, I do have an answer to my own question.  I'd just like to hear someone else's opinion.

Stu

I'd have to raise the point that the system shouldn't fail but sometimes does.Have you ever had the customer arguing with you that they aren't paying for the call  out and associated part because you were only here last week doing the service.
Bit like the MOT being on as good as the day of the test!

[CivvyFSO]

In a shopping mall, it is of paramount importance that when the fire alarm actuates, the correct channelling screens drop, the air inlet ventilators open, the appropriate fans or natural roof ventilators operate, appropriate containment screens drop, dampers and shutters operate as required, HVAC system shut down or adapt as required and so on.  All this is reliant on the alarm system operating correctly and we trust that this will happen.  All I'm saying is, why can't we have the same faith when we're considering doors linked to the fire alarm?

It is my opinion that a failure of all those things at once will be nowhere near as much of a guarantee of a catastrophe as locked exit doors during a fire. I am not saying there wouldn't be a potential disaster, just that a locked exit during a fire just about guarantees it.