Heat detector connections

[beelzerob]

I recently bought some heat detectors (GE, can't remember the model). I was looking over the back of the detector, and noticed 4 connections. I had only expected 2, as I thought it was a simple open/closed device. The directions seemed to indicate I connect my 1 pair of wires to both pair of connections, and then also to an EOL resistor. It didn't elaborate on what kind of resistor, nor what its purpose was.

What is the point of an EOL resistor? I know that it has something to do with making sure the wire is ok, but since my hardware will be looking for a closed connection should the heat detector go off, then how will an EOL resistor mimic that condition of something goes wrong with the wire? I'd imagine fire damage to the wiring would have just a great of change of causing an open circuit as a closed one.

If I need an EOL, what type of resistor? I've got a radio shack nearby....

 

[Digger]

I recently bought some heat detectors (GE, can't remember the model). I was looking over the back of the detector, and noticed 4 connections. I had only expected 2, as I thought it was a simple open/closed device. The directions seemed to indicate I connect my 1 pair of wires to both pair of connections, and then also to an EOL resistor. It didn't elaborate on what kind of resistor, nor what its purpose was.

What is the point of an EOL resistor? I know that it has something to do with making sure the wire is ok, but since my hardware will be looking for a closed connection should the heat detector go off, then how will an EOL resistor mimic that condition of something goes wrong with the wire? I'd imagine fire damage to the wiring would have just a great of change of causing an open circuit as a closed one.

If I need an EOL, what type of resistor? I've got a radio shack nearby....

A typical hardwired Heat (thermal) detector would be 2 wires in (from the panel Zone) and 2 wires out to the next device or EOL Resistor. The EOL Resistor value depends on the panel. In the case of many mfg's it is a 2200 ohm (ELK, NAPCO, Ademco etc).

A fire zone is a normally open zone (NO) and the device such as a heat detector will short the zone when it is activated. The EOL Resistor monitors the integrity of the wiring.

 

[upstatemike]

The reason for separate in and out terminals is to make sure that the detector cannot be removed without interrupting the loop and creating a trouble condition. If it was just paralleled across the circuit there would be no indication if it was removed for some reason. Fire alarm codes require a panel indication if any detection device becomes non-operational.

 

[beelzerob]

Ok, well I think I see the problem here. At least for now, I don't have a panel of any kind. All I have is a datanab sensor system that will tell me if a circuit is open or closed. I'll use that and CQC to do some auxillary services if they ever detect that a smoke alarm has gone off, or a heat detector has popped. But I'm not trying to replace my smoke alarms as the primary method of fire notification. At this point, our main indication will be that they're wired in tandem so they'll all go off. If I can add in some additional functionality like calling my phone, or turning on the lights, or stopping the A/C, etc, then that's what I'm hoping to do.

So in that regard, because I don't have any kind of panel "monitoring" the line....does the EOL resistor still apply to me?

Also, I do have individual runs to each smoke (their relays trip independantly) and heat detector, not in series. I haven't tried to define them in zones, but if I did, I'd handle that in CQC. Either way, if I had to wire them in series, I could do that in the wiring closet.