Wireless Door Magnet Query ...

[David Rooney]

Table 1 of 7273 pt 4 regarding radio door holders and the specific reasons when they should release says .....

g) in the case of radio-actuated systems:

1) a failure of radio communication between the transmission equipment and the release mechanism;

2) short or open circuit of any circuit between the transmission equipment and the fire alarm CIE, external to an enclosure
(within 120 s of occurrence)

A manufacturer of wireless equipment has recently supplied us their new wireless door holder ..... taking it out the box, unprogrammed and unpowered the door plate is attracted to the magnetic holder.

Meaning if this was screwed to a wall and door right now the door would be held open forever, no faults indicated and no one any the wiser unless the fire alarm were tested and someone noticed the door didn't shut.

When programmed on the fire system, the magnet releases as you'd expect under all the listed conditions for CAT A however, failure of the comms (g 1) does release the magnet but the design of the unit is such that the door could be opened following the comms failure and the door would be held open for ever.

Therefore a worst case scenario might be that a catastrophic failure of the transmitter controlling the wireless door holder following an alarm activation, would result in no comms (g 1 ) and the door could be pushed open by an escapee and would stay open forever.

Although the fault would register on the fire panel, am I missing something in the small print or is this non compliant and potentially dangerous even though it's being sold as suitable for CAT A installations???

Or is this acceptable

[Mr. P]

Probably why those in the know insist hard wired hold openers only...

From your comment above [fault register on panel] -would it?

[David Rooney]

Wouldn't go that far ... the wireless Geofire kit works extremely well but on different operating principles.

Not sure what your question is, but yes if the comms failed or batteries failed in the door holder it would register a fault on the control panel, but how often do faults get ignored on a panel ?

... and it wouldn't then stop the door from being held open, never to release again !

[Tom Sutton]

It appears the system is not fail-safe in accordance with BS 7274-4 therefore not acceptable. When they first came out the major problem was residual magnetism which eventually was solved with laminated cores. If the core remains magnetised after it has operated then that cannot be acceptable for reason you have already said.

[David Rooney]

It is a permanent magnet and uses a pin to force the plates apart.

If it loses comms under normal conditions the pin "fires" every 10 seconds or so so the plates can't hold together.

But if the battery in the holder fails then the pin won't fire and therefore the plates stick and door stays open forever.

It has just got all "the approvals" apparently but I don't see how unless there is some twisted interpretation of the BS that I can't get my head around ..... 

[Fishy]

My initial response was "What the...", but on reflection perhaps by having a permanent magnet (rather than needing a permanently energised electromagnet) it might increase battery life significantly?

Perhaps it complies with the standard - but only if used strictly according to the instructions (i.e. you replace the battery as soon as it gets low - like that's always going to happen)!?  It might well be compliant with the standard, but the fact that you can defeat its safety features so easily would mean that I personally wouldn't be happy to specify it.  For example, I could see this being used in a situation where the doors are closed overnight and a fault occurs during that time - occupants could do what they usually do & open the doors onto the magnets in the morning as normal, blissfully unaware of the fault.  Perhaps they should check the panel for faults every morning, and be savvy enough to recognise the implications of any faults shown - but you have to take into account that safety kit ought to be designed so that it doesn't require 100% perfect management to work effectively!

[David Rooney]

My initial response was "What the...", but on reflection perhaps by having a permanent magnet (rather than needing a permanently energised electromagnet) it might increase battery life significantly?

Perhaps it complies with the standard - but only if used strictly according to the instructions (i.e. you replace the battery as soon as it gets low - like that's always going to happen)!?  It might well be compliant with the standard, but the fact that you can defeat its safety features so easily would mean that I personally wouldn't be happy to specify it.  For example, I could see this being used in a situation where the doors are closed overnight and a fault occurs during that time - occupants could do what they usually do & open the doors onto the magnets in the morning as normal, blissfully unaware of the fault.  Perhaps they should check the panel for faults every morning, and be savvy enough to recognise the implications of any faults shown - but you have to take into account that safety kit ought to be designed so that it doesn't require 100% perfect management to work effectively!

My thoughts exactly ...... and in your scenario once the door has been opened in the morning it will stay open forever.

When someone eventually reports the fault it may get fixed but in the mean time it's stuck open.

So assuming this has "all the accreditations" who would be liable ... the user for not understanding the implications of the fault and for not dealing with it, or the company that installed it and didn't include a big bold caveat absolving themselves from responsibility?