Hi I am looking for some advice but realise this post is some 4 years old and regulations may have changed with regards BS 7273-4.
When you have proximity access control system fitted to a final exit door that is secured by a magnetic lock or similar fail safe locking device it is generally battery back up so if the system fails the battery will still hold the door locked until the battery elapses. However without a low battery drop out circuit install a magnetic lock will still hold on battery power to below 3 volts, which will just make the door locked but not very well.
Secured by Design asks for the battery backup facility and also they have outlawed the use of a green BGU.
The BGU will always be a failsafe device dropping the lock supply positive supply via the normally closed circuit (Providing the door is a failsafe/unlocked locking device).
SBD wish the BGU on residential blocks to be replaced using a self-resetting push to Exit switch. This has its challenges as there are not any such devices on the market
A lot of clients are using a PTE which is double pole double throw, so the normally open connect to the timed circuit of the access control system and when pressed produces a timed controlled release. The normally closed set of contacts switch the positive side of the lock, when the button is held depressed. This is a failsafe exit, but it does rely on you being able to hold down the button while opening the door.
So as a backup if there is a FA or AOV system most installer will connect the access control system to the FA or AOV system, which makes sense. However a lot of installers are just connecting the FA/AOV to a timed release of the access control using CAT5. In my mid this is wrong as if that trigger fails the doors will not open. Is there any rules in BS7273-4 or any other regulations that state there should be a local I/O relay connected to the FA/AOV that has the power of the lock going through the Normally open, held closed contact, so when the FA/AOV system are triggered the power to all I/O relays coils are dropped so the relay fails open thus failing the lock supply opening/unlocking the door as this appears to be a grey matter. Also should all lock supply cables be a minimum of 1.0mm as many are using CAT5 cables to power these locks.
How do the rules differ between a FA system and AOV system when it comes down to unlocking a final exit door with access control?
SBD are also trying to replace the fire man drop key switch with a global latching switch which when operated unlocks all doors. What’s the rules here about a global trigger? To achieve this surely it need to be a fail safe operation as if it’s just a trigger to the access control, if the trigger or trigger cable fail the doors will not release.
