Digital Fire Alarm Control Signal

Since you have mentioned "flashscan" protocol, you must be using Notifier equipment, as that is the protocol which replaced their older "CLIP" protocol. Incidentally, older CLIP devices can be used on Flashscan SLC loops, but can only be used in program addresses 1-99.

You can use standard UL Listed FPL (free wire or in conduit), FPLR (riser wire between floors), or FPLP (free wire in plenum areas) wire for your SLC loop. If you are running your loop near high voltage or high electrical noise wiring or equipment, you should use shielded wire and ground the shield at the panel end ONLY. All of these wire types are available in shielded and non-shielded versions.

Your information to the point. However.

But why Capacitance and Resistance of SLC are restricted?

Is it due to SLC nature itself, detection device or Control Panel?

Wire resistance is the limiting factor. Using 12 AWG wire, you can have a maximum of 12,500 feet of total SLC cable.

Make sense and interested to know why only the resistance is the limiting factor and what about 14 and 16 AWG?

Hope answer with more detail if possible.

Excessive wire resistance causes voltage drop, which causes the network to stop working.

Let's play 1 question instead of 20 questions. What is the measured length of SLC cable you plan to use ?

Length of SLC shall be 5400 Feet.

You can use 16 AWG un-shielded cable. If you must use shielded cable, increase size to 12 AWG.

Use type FPL cable, which has a slight characteristic twist.

I can understand your selection and would appreciate it if you could you advise the source or basis of your cable selection?

Is it feasible to instal FPL Cable in metallic coduit?

1. Application Note 916 A Practical Guide To Cable Selection ...
2. [PDF] Power Cable Selection Guide
   
3. 
   
4. [PDF] Cable Selection Guide - Grainger