first fire alarm system job

[hursty]

I have my first fire alarm system job coming up and there are a few questions i have, if anyone can help me that would be great.
I understand the wiring, series connections, with a resistor at the end of the line for the 2 wire system.

Looking at the fire detectors on the base are L1 in, L1 out, L2 and -R. just wondering what the -R connection is? is it to do with EOL?
Each detector has a small resistor always connected in the terminals, and in the panel there are larger EOL resistors, i believe that I remove these from panel and connect onto the end of line detector?

hope you understand what i mean.

cheers

 

[telectrix]

R is for remote LED. used when detector is in a cupboard or lift shaft etc. the component in each detector is usually a diode. you are right as regards the eol devices. note that the ones for the sounders may not be the same as the ones for the detectors. don't mix them up.

the connections are usually + in, + out, and the - is common to 1 terminal.

 

[hursty]

thanks for reply.
the sounder resistors are different? the sounder i have has just a simple in +, and out -, and that is just connected in series with all other components yes?
with regards to the EOL devices, is it correct that you just connect them in as the outgoing + and - ?

thanks again

 

[telectrix]

not in series. PARALLEL.

the eol devices just go across the + ans - at the last detector/sounder. think about it. the panel is looking for that eol device. say it's 22k ohms. a detector going into alarm will put roughly a 470 ohm across the pair, signalloing the panel to go into FIRE. if it goes open circuit, say the cable is cut, the panel then goes into FAULT. the impedance of the cable is so low in comparison, it can be ignored.

 

[hursty]

sorry bit of confusion there. Detector/break point radials are series and sounder radials are parallel.

Yes im back with it now, depending on the type of panel which will be supplied, the sounders are indepentant from any zone radials? as the sounders are on there own radials, or will that all depend on how the panel is configured?

 

[IQ Electrical]

Hi Hursty, are you familiar with the requirements of BS 5839 with particular reference to cable supports/clipping/containment?

 

[telectrix]

sorry bit of confusion there. Detector/break point radials are series and sounder radials are parallel.

NO. everything is parallel. and as IQ says, there is a lot more to it. fire alarm cables must be run separate from all other circuits. plastic clips are a NO-NO.

 

[alarm man]

Hi Hursty, are you familiar with the requirements of BS 5839 with particular reference to cable supports/clipping/containment?

agree with iq,installing it is the easy bit which i think you may struggle with,if its your design also get that wrong and you have some questions to answer

 

[Engineer54]

I wish some of these guy's would at least get some experience of installing specialised systems, before they jump in with both feet.

FA Systems are not exactly difficult to install, test or commission (provided you have the right testing kit that is) but they do still come with there own set of reg's and rules that DO NEED complying with.

These day's there are so many different types of FA systems, that you really do need to know at least, what wiring system your FA requires!!

 

[hasel5]

is it a rafixie system