Fire Alarm Relays 24V

[IAmSparkytus!]

Good evening!

Don’t have a huge deal of experience with fire alarms but having to work on a conventional system at the minute with various signals and “shut offs” being activated by the on board relays.

All relay outputs currently used up in the panel but need to setup another “shut off” for an extract fan.

Planned on installing a 230V DP NC contactor with a 24V coil which could be fed from a sounder circuit but then didn’t know if this would work as it may need to be polarised - can anyone advise on this?

There’s a 24V polarised relay within the system fed from the panels relays. Is it feasible to double up in its supply terminals and take 24V from there?

Any advice appreciated.

Thanks.

 

[Mikegh]

You could maybe use one of the relay outputs to control a secondary relay which provides 2 further relay outputs ?

Thinking out loud . Not sure that's feasible or otherwise

 

[IAmSparkytus!]

I’ve seen plate relays with 24v supply in and 24v supply out terminals but this one hasnt and that made me wonder why and whether it could just be doubled up

There’s already a lot of “this relay feeding that relay to allow for additional relays” going on within the panel so didn’t want to go down that route again. Don’t ever have a lot to do with relays, is this common?

 

[MDJ]

Good evening!

Don’t have a huge deal of experience with fire alarms but having to work on a conventional system at the minute with various signals and “shut offs” being activated by the on board relays.

All relay outputs currently used up in the panel but need to setup another “shut off” for an extract fan.

Planned on installing a 230V DP NC contactor with a 24V coil which could be fed from a sounder circuit but then didn’t know if this would work as it may need to be polarised - can anyone advise on this?

There’s a 24V polarised relay within the system fed from the panels relays. Is it feasible to double up in its supply terminals and take 24V from there?

Any advice appreciated.

Thanks.

done this myself a few times on a conventional system. You can use a sounder of bell to send 24 volts for a supply to a relay coil, you may well need to use a diode though where the supply connects to the relay so the sounder circuit does not show up as a fault on the panel.

 

[IAmSparkytus!]

So update on this… all working well but need the relay to stay latched when the silence button has been pressed on the panel.

Was looking to fit a latched relay inline between the panel and the contactor but can’t seem to find any.

Any fire panel experts on here?

 

[IAmSparkytus!]

So update on this… all working well but need the relay to stay latched when the silence button has been pressed on the panel.

Was looking to fit a latched relay inline between the panel and the contactor but can’t seem to find any.

Any fire panel experts on here?

PS. Would need to be a resettable latching relay.

Just found online that you can get an extension board for with additional relays on but not sure how and if this would work.

Exploring all possibilities at the minute.

 

[Flanders]

If you have spare normal open contact you can send a 24v contactor coil supply through the normally open contact Then you will need to fit a push to break switch on the same circuit to reset the contactor

 

[IAmSparkytus!]

There’s a spare NO terminal on the fault relay but something already connected into the C and NC terminals. I believe they’re being used to send a signal to another panel so not sure if this NO could be used?

 

[Darkwood]

Just an heads up here, any expansion or addition to the control system of a Fire Alarm should be suitable for the job in hand and I don't mean just functionally operational, you are working on a safety critical system so any modifications you do should ultimately meet the same level of standards that the panel itself is designed to and depending on the function of any additions do it may require higher standards, so may even warrant a small control panel build with redundancy and safety level rated parts like force guided safety relays which are typically used in machine control safety systems.

Using manufacturers own expansion modules maybe one way to accomplish this as long as you ensure it is suitable for what you are doing, if in doubt contact the manufacturers, driven your own bog standard relays may not suffice.

May I ask who has requested the extractor fan be shut off?

If building control, architect and/or the local fire department then you will need to run any design by them and it is down to you to ensure it follows British Standards associated with the system type and premises you are working in, it is not for them to know or understand if it complies unless they have independent guidance and instructed you how to do it.
You will need to submit a detailed report filed with the rest of the fire alarm paperwork on your additions, if for any reason your additions failed in a real fire and someone came to harm then everyone is going to be trying to pass the book for any design issues IE you and it will be down to you to demonstrate you fitted a compliant addition that met regulations

I always advise anyone dipping there toe in this area to stay well away if unsure especially if they don't own the latest standards for design and install of Fire Alarm systems, I'm often little less concerned with domestic as its often easy to explain and pick up.

With regards to your situe and only off the limited info you have given (so don't take it as correct advice) I would get an expansion module from the manufacturers, if it is crucial the fan shuts down for safety reasons then a safety panel needs making with safety contactors in series for redundancy, a monitored reset through a safety relay so any failure of the contactors will inhibit the reset function. I have done such systems before more so on machine guarding but also on a Fire Alarm for gas valve into a multi occupancy building after one failed to shut off during testing due to poor design and a failed contactor.

I reiterate, my comment is for example only and may not reflect the set up you have and may not be suitable as info is limited.