Micro switch push bar for public assembly usage

[G. N. Hamilton]

I was wondering has anybody came across these. Are they deemed to provide an equivalent standard to BS EN 1125. On the face of it, it would appear that the exit is available at all times upon activation of the push bar. Also incorporates fail safe upon activation of AFDS, power failure, etc.

Appendix B of Fire safety Risk Assessment for large places of assembly refers to electro magnetic locks and states: "In public areas, when push bars are operated on escape doors, they should release the electromagnetic locks immediately and allow the exit doors to open".

There are various available from what I can see, here is an example

http://wdbmedia.com/PANICEXITPRO/MANUALS/ACCESSORIES/sentry-e-labs-PBA-860.pdf

[kurnal]

I have seen these things and not given them particular thought, can't really see the point of a mag lock in these circumstances. I remember seeing something about them in the assembly guidance and remember a thread on here about the confusing way it is described in the guidance.

My initial thoughts would be that it is unlikely that the micro switch directly controls the lock without some kind of control system and that one would expect that the switch would break the circuit releasing the lock. But if  the switch only triggers a control circuit there is more room for failure.

I would also expect that the locks would also be required to be interfaced to the fire alarm and so the whole set up would then be subject to BS 7273-4 which would provide the necessary safeguards. And though not suitable generally for assembly use such safeguards would probably include a green break glass box.

I hasten to add these are my ill considered thoughts and rumblings.

[AnthonyB]

I've seen mag locks added as a security measure on several occasions - my approach would be "does this exit need to be panic proof" based on the occupancy profile, numbers & purpose group.

Where the answer is yes, then a green break glass is not adequate as the exit is nor panic proof and pressure alone on the bars will not open the door - the fire alarm interface and fail safe on power loss options must also be present.

Whilst this suffices for a fire led evacuation & in situations where the fire alarm is likely to sound early on before the exit flow is likely to reach the doors there is still a vulnerability where the alarm is not activated quickly or the evacuation is not due to a fire.

The linked product may theoretically overcome that, but would be unpopular with some clients as it would defeat the point of the mag lock, i.e. deterring casual use of the exit via the panic bolt.

[G. N. Hamilton]

In this specific situation it is proposed to improve security from the external and to facilitate staff access by keypad, therefore not to improve security in the DOE.
@ Kurnal, that's exactly what i'm worried about, that there is a contact or whatever that could fail and prevent the signal from going the micro switch to the EM lock.

[Clevelandfire 3]

On the other hand whats the difference between that push bar and a human finger pressing the button in a green EBG unit. in other words if push bar acts like the human finger pushing a button and the micro switch is the same as the gubbins found in a green box surely its happy days. Like you said ive seen this when you want to control security from the external side otherwise it would serve no purpose.

[kurnal]

Nothing if it's double pole and directly breaks the supply to both sides of the electromagnet. But is it and does it?

[wee brian]

I've seen them before - you can and should wire them so they break the power to the maglock without the need for communicatrion with the control system.