fire alarm cables and telephone cables

[relax_08]

hi dear!

is it possible to put the fire alarm (1.5mm2 UC/PVC wire) and the telephone cables (2pair UTP) in one conduit???

Do this situation will not interfere on their corresponding signals?

Please help.
THanks a lot.

 

[pranam77]

Wether it interfere's depend on what signals do you pass on these....Its understood that wires used for telephone will have telephone line signals but you didnt mention what signals of the burglar alarm will be passed over the wires. Wether its a sensing IN, or a siren Audio, DC volatge or an AC voltage?

 

[relax_08]

hi there.

sorry for inconveniene sir. DC voltage just to give power for the fire alarm devices.
Thanks.

 

[pranam77]

You can run the two wires together, without any problems in one conduit. But do use filtering capacitor for the DC line when it is connected to the circuit for safety. Cheers

 

[relax_08]

for safety reasons? what will happen if i will not put that filtering capacitor?
Thanks.

 

[betwixt]

There will be some transfer of signal between the cables because of their close proximity. The amount is difficult to predict as it depends on the relative positions of the cables and length they lie together. Telephone wires often carry quite high voltages, usually more than 100V when ringing, this could cause enough ripple in the alarm wires for the system to mistake it for an alarm condition. Placing filter capacitors across the alarm supply will help to minimize the signs of the 'cross talk' between the cables and should lessen the chances of a false alert.

Brian.

 

[relax_08]

thanks a lot.
and what should be the specification of the filtering capacitor? how does it works?

 

[betwixt]

The filter capacitor really depend on the power requirements of the alarm circuit but if you use 100uF and 100nF in parallel, rated at least 20% higher voltage than the power lines carry it should work well.

Brian.

 

[ashokok]

hi relax_08 can you tell us the make and model of the panel and Detectors and your from which country.



P.Ashok Kumar