I have never owned a panel before but may get one soon.
1.) if the NAC is in activation and the wires short, will the panel get damaged? Or will it just go into trouble.
2.) for a supervised panel, is it okay just to use a single positive and negative wire and ingnire supervisory in all?
Panel: Cerberus Pyritronics SXL-EX
Thanks fam!
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Most modern panels use electronic protection circuits to limit current and/or shut down a NAC in an over-current situation. However, these circuits are not perfect. If a NAC is in active alarm mode and a dead short occurs it is pretty much a guess if the protection can react before the panel sustains damage.
I am trying to figure out what the question is asking. All panels have supervised IDC and NAC circuits. All fire alarm circuits have a positive wire and a negative wire. The most puzzling statement is “and ingnire supervisory in all?” I find that “ingnire” does not seem to be an English language word. What is being asked in the statement “in all?” In all what? The question is unclear.
Supervisory lines require a negative wire and two positive wires. If the two positive loose contact (ex. Detector removed, Na removed etc.) the panel will go into supervisory trouble. Is it possible just to use one of each positive and negative as a pure 2 wire system? The word I meant to put was IGNORE but iPhone keyboards are so small. If the last positive supervisory is left out, would the panel show a trouble all the time?
Sorry if this is super confusing. My apologies.
Class B Supervisory circuits use two wires (one positive, one negative) along with an EOL resistor installed on the last device to supervise the circuit. There is no second positive feed required.
You are confusing this concept with that of smoke detectors and horn/strobes with mounting bases. These devices have two terminals for wiring the positive inputs, however only one positive feed is required on the circuit. As explained by chris+s:
To add to what Chris and Nick said, if you don’t use the proper end-of-line resistor, the circuit(s) will go into trouble, as the resistor is paramount to supervision.
If you’re wondering about why some devices have two positive terminals, it’s so that one positive wire is wired to the previous device, and the other is wired to the next device. If you wanted, you could do all that on one terminal anyway, so it’s a tad redundant.
I took a Simplex smoke detector base wiring diagram and simplified it to show the basic wiring. In this case there is one terminal for the positive side of the zone and two terminals for the negative side of the zone. The separate terminals for one side of the IDC is for detector head supervision. Whether to use the positive side or the negative side to accomplish the detector head supervision is up to the manufacturer.
In the drawing terminals 1 and 2 have parts that form a contact that closes the connection between them when the detector head is installed in the base. If the detector head is removed that contact opens which breaks the connection to the End Of Line Resistor so a trouble will show on the panel. Terminal 4 is the positive side of the circuit. The two wires that go into terminal 4 must be separate wires, not a loop with the insulation removed. That is to provide supervision if that connection is broken somehow. Terminal 3 is used for the external LED connection if needed.
Oooohhhhhhhh that makes a lot more sense now.
Thanks yall
the metal contacts closing (opposed to a diode) is a very common method, but i’m not a fan. if smoke #1 is removed, you lose every other smoke on the line. i’ve also seen detector bases where the detector makes the connection between the separate terminals internally whenever it’s installed.
most NAC’s with bases i’ve seen utilize the metal contacts.
