Proper FA wire for EST- 3 devices

[deestech]

Greetings,

Just installed an EST-3x in our warehouse distribution center (450,00. sqft). We began having problems with unwarranted fire alarms from the new SIGA-SD duct detectors.

The detectors are clean, and we still get alarms. There is no humidity and they are not too close to halogen/fluorescent lighting.

The FA contractor estimates that it could be the high capacitance in the FA cable. We used armored FA cable from AFC cable systems, Type MC, so we can avoid using EMT throughout the large facility. There are no problems with the visual/audible device loop. The problem exists only with the duct detector data loop.

Is this cable acceptable for use with the EST-3 or EST-3x? I tried to reach out to Edwards, but could not get an answer.

We have a big problem and re-wiring the entire system will make it worse. I hope the cable is not the problem.

If anyone can help me with this matter, I would greatly appreciate it.

[Leo]

how many SD?
you could try replacing the siga-SD with conventional SD they look the same (hard to talk the difference by just looking at)
replace the board in the duct detector and add a siga-ct1

[deestech]

We installed 47 (SIGA-SD's) on the data loop. I would rather not rewire the whole loop just for a few SD detectors.

Thank you very much, I appreciate your help. I will look into replacing the SDs (or boards).

[Firetech1701A]

I don't see the Cable being an issue is it the same duct detectors over and over or just random ones? Are you using the on board relays for shut down?

[deestech]

Were using the same SIGA-SDs in the return and supply ducts. All duct detectors are the same. We installed separate relay modules for fan shutdown (not onboard).

I really don't think this is a FA cable issue either. I think the FA, type MC, cable was a good choice. What does the capacitance in the wire have to do with initiating alarms???

Thank you very much for your response.

[Firetech1701A]

are you seeing the same duct Detectors going in to alarm over and over again? Is it supply or returns going off?

[deestech]

Its random detectors (but not all). We checked the sensitivity and its good. We hade a duct detector go into alarm mode 2 weeks ago) even when the fan unit was off, and 0% sensitivity.

This is a new FA system installation, and the problem began 6 weeks after it went on-line.
Thank you

[deestech]

Hello,

Can anybody confirm if the Fire Alarm cable (armored type MC-FPLP from AFC cable systems) is compatible or not with the EST-3x. I cannot get an answer from Edwards. We used 16/2 and 14/2. Data loop is shielded.
I'm concerned that the Fire Protection Engineer specd-out the wrong fire alarm cable.

Thank you very much

[fasiwi]

Use an oscilloscope to investigate data in SLC. If capacitance is high you will see "rounded" data signals in screen.

[Leo]

I forget to ask if the duct that are false alarming are on the same SLC
We had the same problem, we move the false alarming ducts to a different SLC
you could add an SLC to help, just move same devices off the falsing SLC loops