L2 Fire Systems

SSE · Jan 20, 2013

Hi guys looking for a bit of advice on these. I've done a small bit of research so have a rough idea about these but a few things I'm not sure about. Any time I've done fire alarms (not much admittedly) they've always been wired in a loop but I understand you can just wire them in a radial as well. What's the difference ie pro's & cons? Also for the fire exit lights are these wired off the lighting circuit in the consumer unit or as part of one of the circuits from the fire panel?!

Sintra · Jan 20, 2013

SSE said:
Hi guys looking for a bit of advice on these. I've done a small bit of research so have a rough idea about these but a few things I'm not sure about. Any time I've done fire alarms (not much admittedly) they've always been wired in a loop but I understand you can just wire them in a radial as well. What's the difference ie pro's & cons? Also for the fire exit lights are these wired off the lighting circuit in the consumer unit or as part of one of the circuits from the fire panel?!

Hope this is a wind up

i=p/u · Jan 20, 2013

Lights are off the lights and think loops are only used in addressable systems from what I've seen. Remember to stager your sounders , loads more but I vdont know it inside out YET

chrish_1977 · Jan 20, 2013

I have only done a couple of alarms, but I find if you research the different types then you should be able to install the correct system for the requirements, try aico

Welchyboy · Jan 20, 2013

Ha cracker!

SSE · Jan 20, 2013

Sintra said:
Hope this is a wind up

Afraid not, someone tried telling me they thought the lights came off the panel as they would automatically light up if the alarms went off etc... I thought that sounded a bit strange along with another couple of bits of information he told me hence the reason I asked here! I've only helped wire fire alarms twice tops & was a fair while back!

telectrix · Jan 20, 2013

never seen em's wired from fire alarm. always from a local lighting circuit. your exit lights should probably be maintained anyway, having them light only if there's a fire is pure daft. IMO.

SSE · Jan 20, 2013

i=p/u said:
Lights are off the lights and think loops are only used in addressable systems from what I've seen. Remember to stager your sounders , loads more but I vdont know it inside out YET

What do you mean stager?

telectrix said:
never seen em's wired from fire alarm. always from a local lighting circuit. your exit lights should probably be maintained anyway, having them light only if there's a fire is pure daft. IMO.

Nor have I but like I said I've never done much fire alarms at all.

Also what height for breakglasses & sounderrs? Or will it be in the on-site guide?

telectrix · Jan 20, 2013

well, keep them separate and independent. BS5839 for fire BS5266 for emergency lighting. find out exactly what is required by local council/fire brigade.

tazz · Jan 20, 2013

I really hope you not just going to guess at this.
I presume you have been ask to design an L2 fire alarm system, which apart from have an area within an area is designed as an L1 system, every area must have protection.
1. You need to evalauate the areas of each room and circulation areas for protection
2. evaluate db levels for sounders to achieve +65 db in all areas ( if hotel +75db in bedrooms)
3. Calculate loop designs for loop current and battery requirements (max 500mA per loop, 24hr standby and 30 mins alarm)
4. CAD and design the system then sumit to building control or main contractor for approval.
5. First fix the system (cable it)
6. 2nd fix the system (fix detection/sounders)
7. Write the program and upload (with caurse and effects requested)
8. Test and commission the whole system (operation of detection db levels in all areas)
9. Sumit full O&M manuals (cad drawings, zone charts, cable test sheets, db levels, loop battery calcs, caurse & effects and full programme data.

Hope you find time to read this brief listing of fire alarm design and installtion.

Sintra · Jan 20, 2013

Here as a guide to FA systems that might help

MDJ · Jan 20, 2013

SSE said:
someone tried telling me they thought the lights came off the panel !

Wasn't a bloke called Bob down the Local Pub was it fella?

SSE · Jan 20, 2013

telectrix said:
well, keep them separate and independent. BS5839 for fire BS5266 for emergency lighting. find out exactly what is required by local council/fire brigade.

Will do. Cheers.

tazz said:
I really hope you not just going to guess at this.
I presume you have been ask to design an L2 fire alarm system, which apart from have an area within an area is designed as an L1 system, every area must have protection.
1. You need to evalauate the areas of each room and circulation areas for protection
2. evaluate db levels for sounders to achieve +65 db in all areas ( if hotel +75db in bedrooms)
3. Calculate loop designs for loop current and battery requirements (max 500mA per loop, 24hr standby and 30 mins alarm)
4. CAD and design the system then sumit to building control or main contractor for approval.
5. First fix the system (cable it)
6. 2nd fix the system (fix detection/sounders)
7. Write the program and upload (with caurse and effects requested)
8. Test and commission the whole system (operation of detection db levels in all areas)
9. Sumit full O&M manuals (cad drawings, zone charts, cable test sheets, db levels, loop battery calcs, caurse & effects and full programme data.

Hope you find time to read this brief listing of fire alarm design and installtion.

Yes been asked to design one as more of a favour to someone. Just trying to gather information on it as like I said I've very little experience! Thanks for your briefing, will look into all points.