Fire Alarm Loops? Separate sounder loop?

[Snapester]

Should a fire alarm be wired in two separate loops one for call points and detectors and a separate for sounders?
I heard this today and wasnt sure it was right, does anyone have any detailed info on how loops should be wired, if there should be 2 loops or all devices on one loop being ok?

 

[telectrix]

generally, the detectors and the sounders are totally separate circuits. however, some systems run both on the same circuit.

 

[Snapester]

Well this is what i thought, i have installed self addressing systems on one loop, and when i heard that they should be on separate i was like really!

 

[tazz]

On a addressable system, all devices and sounders are on one loop. A loop being the point, starting and returning at the control panel. Isolators are installed every 20 devices are important to the system protecting the loop. This type of system is prefered by most installation companies and is explained full in the BS5839 and does not require sounders to be install on seperate circuits.

 

[Nolnoc]

On an addressable system you can also have seperate conventional sounder ccts,which are seperate from the loop and wired in a radial.This is usually down to cost as conventional sounders are cheaper than loop driven ones.

On an addressable it would be a bad idea to have detection on one loop and sounders on another.If the loop card fails,which can happen no sounders will operate

 

[alarm man]

this is a decent little guide

BS5839 Guide Booklet

 

[Guest123]

Addressable systems have all devices on the same loop as described above.

Conventional systems have separate detection and sounder circuits.

 

[tazz]

Good point nolnoc, Shouldn`t happen but you never know. Hochiki guild is a great little reference Alarm man.
just a little bit worried here that loop caculations etc will not be done and checked before installation.

 

[alarm man]

On an addressable system you can also have seperate conventional sounder ccts,which are seperate from the loop and wired in a radial.This is usually down to cost as conventional sounders are cheaper than loop driven ones.

thats fine on a little system,but if its a big factory etc loop sounders or sounder bases will be way cheaper than running an additional sounder circuit

 

[Nolnoc]

thats fine on a little system,but if its a big factory etc loop sounders or sounder bases will be way cheaper than running an additional sounder circuit

Agreed,if it's a new system. They also leave you limited on strategy.A lot of the time if it's an upgrade existing cabling is used. A sounder control card is sat on the loop and sounders just wired off them.Not a great idea IMO but sometimes needs must

 

[alarm man]

Agreed,if it's a new system. They also leave you limited on strategy.A lot of the time if it's an upgrade existing cabling is used. A sounder control card is sat on the loop and sounders just wired off them.Not a great idea IMO but sometimes needs must

fair point,tho if your upgrading from a coventional to addressable your going to have to rewire in some way as it wont have a loop for the detection,you could add a sounder mod to power the sounders but as all the detection will need replaced anyway its better to go for loop sounders

 

[tazz]

Just been to an nursing home today to upgrade a old morley ZXA system today, which might be of interest. I did the usual download was pres 2000 so was in dos (old windows)..check download, a bit narrow over 120 devices on both 2 loops, then checked currrent load on bell circuits 1.5 amps on circuits A and B wow checked out circuits 20 sounders and 20 strobes on each bell circuit which was crashing panel..so disconnected strobes, and now bell circuits now down to 300ma. then tested batteries with ACT meter the 2.1 a/h batteries did not even register total dead. Loop calcs show 12.2 a/h was needed for system. All smoke detection was fitted outside each door at 4 to 5 inches from each door leaving 30m of uncovered space down corridors....so ne panel fiited with 17/H batteries and a V1 form issued for variantions.
his system was fitted over 12 years ago and has been maintained by the same company todate