Electromagnetic emergency door release mechanisms (EDR)

[Stinky]

Hello,

I have a query regarding the green box emergency door release mechanisms, particularly to electromagnetic access doors.

Is a green box essential if;
1. the door releases on activation of the fire alarm,
2. it fails safe on loss of power and;
3. a normal day to day opening door release button is provided. 

Is there a need for a emergency door release (green box) as well? 

I have read through 7273-4, but I can't figure out whether one is recommended.  It just talks about them but does not appear to stipulate where one is recommended, unless I have missed that part.

Any help would be much appreciated.

[Wiz]

Stinky, I think the answer is that they are always needed. That is why BS7273-4 doesn't talk about the circumstances when you do need them because you should always have them (except in high-security institutions such as places of detention).

[Stinky]

Well that's what i've always recommended.  But looking at a particular circumstance, it fail safe's on power, it releases on fire alarm and there is a button to open the door if power is on.

I suppose there is the situation where a fire has not been detected yet and the button has failed. This is possible and people would be trapped. 

I don't understand why these were not fitted in the first place then?  If they are required in all instances.

[AnthonyB]

I don't understand why these were not fitted in the first place then?  If they are required in all instances.

Because like with fire alarm installations/fire extinguisher provision/emergemcy lighting/risk assessment/enforcement there are a lot of people out there who don't really know what they are doing.........

The push to exit can fail and also still allows relocking, interrupting exit flow as everyone has to keep pressing the button if there isn't a steady stream - also some push to exits are notoriously fiddly to work and can sometimes be located some distance from the door.

[Phoenix]

Could I ask where it is recommended that they are fitted to all security doors required for means of escape?

Stu

[CivvyFSO]

The standard states that it applies where a mechanism for locking/opening/closing a fire door or escape door is connected to a fire alarm. If a door is locked mechanically or electromagnetically, but not connected to the fire alarm then the standard doesn't apply. It also states that if there is a mechanical option of opening/unlocking the door then parts of the standard might not apply.

However, if an electro-magnetic or electro-mechanical system is securing an exit door, then in most cases by virtue of article 14 (must not be locked ro so fastened etc) it would need connecting to the fire alarm, meaning 7273-4 applies by default once that connection is made.

[Wiz]

Stu, try Clause 8.2 of BS7273-4 which mentions 'manual controls' and also refers to Clause 12. Clause 12 is all about how the switch should look, be labelled, be wired etc.

[Phoenix]

Thanks guys,

I know we've discussed this at length before.  I was just after the actual reference.

I would say, though, that there are times when the green box is not required.  For example, sometimes the door is electronically secured but there is a handle on the inside which over-rides the electronic security device.

Stu

[Wiz]

.....I would say, though, that there are times when the green box is not required.  For example, sometimes the door is electronically secured but there is a handle on the inside which over-rides the electronic security device.

Stu

I believe the BS agrees with you Stu, and specifically mentions what you are saying.

[CivvyFSO]

From the 'Introduction' part:

"Where such mechanical means of releasing locks is provided, the full application of all recommendations in this part of BS 7273 might not be necessary."

[Phoenix]

Well, there you go.

[TFEM]

A customer of ours (a large educational building) is just having a number of old fire exit doors (with crash bars) replaced with sliding electronic doors. They are NOT linked into the fire alarm but default to open on power fail. They have green EDR's. The doors also have manual key locks (presumably for security reasons) which, as I discovered, COULD remain locked if forgotten to be opened by the caretaker.
Is it sufficient for the customer to say "we have assessed the risk and consider it minimal"?
I also thought that sliding and revolving doors could not be used as fire exits?
Your thoughts would be appreciated.
John

[CivvyFSO]

The way I would look at that is the doors SHOULD be linked to the fire alarm, and then the requirements of 7273-4 become necessary.

The Order is quite clear that "where necessary" sliding/revolving doors should not be used on the means of escape, but you could question the actual meaning of "sliding-doors". I think it could be assumed that the doors that they really mean would be the typical 'manual' sliding door found in warehouses and industrial risks. After all, if a door opens automatically upon operation of the fire alarm, it is no longer really a sliding door across the means of escape. (But we need to ensure that the system is failsafe, hence the recommedations of 7273-4)

Most external doors have some form of lock/security that could be forgotten about. This is a management problem covered by adequate opening up procedures.