Can't get smoke detector to trigger ELKM1G


Active Member
Hi all,

I just installed a System Sensor brand 2WTA-B smoke/thermal detector and, while it powers up great, I can't get it to trigger my ELK panel that it has gone off (using a lit punk to "Smoke" it.

Although it is listed as a 2-wire detector, I have it powered from the SMOKE AUX PWR on my Elk panel. I have an EOL resistor in series with the Zone 16 wiring across the alarm contacts of the smoke detector using CAT 5 cable.

I've tried hooking it up with no 2200 ohm resistor and also with the same resistor across the alarm contacts as shown in the instructions but all that does is put FIRE TROUBLE on my Elk keypad.

The unit is wired to Zone 16 with that zone set to "Normal" mode. Hopefully this will still allow the power to the unit to be cycled to reset the alarm (if I ever get one!).

The smoke detector works and will sound loudly during the smoke test, but the Elk is blissfully unaware that it has gone off.

Any help would be appreciated.

Smoked-out in Houston
You should be using an 820 ohm resistor for zone 16 when using a two wire smoke. That might be part of your problem. There should be one in your bag of resistors that came with the elk.

Check out page 4 of the installation manual (center of the page).

They don't need to be powered from Smoke Aux if it is on zone 16. I have those detectors and you hook it directly to zone 16 and set the jumper properly.

Also for testing them you might want to check out the canned tester here:


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If his panel is old stock it might have the 680 ohm resistor in the package. Easy to fond an 820.

Is fire verification on? That may cause some confusion.
That is a good point, I thought the models listed on the piece I cut out looked newer than what I had but didn't think much of it. Now that you mention it the System Sensor model was 'translated' in the past from an older model (but still compatible).
Yes, I wish Elk would update their specs on acceptable 2 wire smokes given that many of the models they list have been replaced.
Thanks everyone for the input.

I'll install an 820 ohm resistor across the contacts and see if that helps. By running it in "two-wire" mode, will the Elk be able to cycle the SMOKE AUX PWR to reset the detector from the keypad?

Digger: The panel was bought about 2 months ago so it should be current (?). Where do I find information about the "Fire Verification" you spoke about?

Thanks again
The power for Zone 16 2 wire smoke is derived from the SAUX bus (thats why you have to rememember to set the jumper). So when you do a smoke detector reset you do the Saux and Zone 16 if its setup as a 2 wire smoke zone.

I forget where the fire alarm verification is enabled. You can check the manual.
HoustonFirefox said:
Where do I find information about the "Fire Verification" you spoke about?
Look in the zone definition table, around pg. 30. It's Definition #11:

11 Fire 24 hr ‘Verified’ - For smoke detectors in high-risk false alarm areas. Upon initial activation (short across the zone), the control ignores the alarm and removes smoke power for 5 seconds to reset the detectors. During this 5 seconds, and for 25 additional seconds afterwards, no alarms will be recognized from this zone. Following this is a 30 second verification time window, during which any additional activation will be regarded as verification of the initial alarm and the control will initiate a Fire Alarm. If the 30 seconds expires with no further activations, the entire process is cleared (reset). A Fire Trouble will be activated if an open (break in the zone wires) occurs.
Hey All,

Finally got around to trying to fix the damned thing again and no luck. As I sit here, "Fire Trouble" is happily blinking away on my keypad.

The instructions are not terribly clear but here is what I have set up for the smoke detector:

SAUX (12vdc) from the panel is going to (1)+ IN and (3) - IN/OUT to power the detector.

Zone 16 is wired to the 4(A) and 5(A) alarm contacts at the detector. I have an 820 ohm resistor across both of the alarm contacts as shown in the instructions.

The panel has the jumper set for a 2-wire smoke (although hopefully it will reset SAUX to reset the smoke detector).

Why can't a darned smoke detector be as easy to install as anything else? NC or NO contacts and a damned EOL resistor?

Any help would be appreciated

Baffled in Houston
You should be running the wire from zone 16 to the detector. I just went down to verify how mine is setup and there is no connection to saux, just to zone 16.

That might be part of the problem.

As far as the wiring, I think it is still off, try this:

Zone 16 + to (1)+ on the detector
Zone 16 - to (3)- on the detector

820 ohm resistor across (2) and (3) on the detector.

That should do it.
4 and 5 are for remote annuniciator functions. There should be no connections to SAUX (for this detector at least).

Let me know how that works.
Mike is correct just set the jumper to 2 wire smoke and attach the 2 wires for the zone to the Zone 16 terminals. Place the EOL after the last detector like you would any other burg zone and you are done. (The SAUX is connected only if you have 4 wire detectors).

I have used the same detectors with no problems. I actually had 20 on the zone working fine.

BTW these are great detectors.

Now finally some results!

With hesitation, I removed the SAUX power from the detector completely and wired the zone +- across (1) and (3) as listed. In addition, I put the 820 ohm resistor across (2) and (3). The detector powered up fine, started blinking the green light and No Fire Trouble at the keypad.

There was, however, a bit of "trouble" when I smoke-tested the detector and the Elk went screaming into the night (11:53pm) with a fire alarm. I was smart enough to disconnect it from the phone line before the test but the outside strobe and voice "Fire! Fire! (BLAP!, BLAP!) Exit immediately! Garage Fire!" was heard at least a block away.

At least I know my neighbors will pay attention to it (sheepish grin).

Thanks for the help all. I was under the impression that it had to have a separate +- 12v power in order to work (hence the RA +- connections). Apparently it is happy working just off the low current from the zone 16 output.

Thanks again for the help. I'm assuming that further detectors should be two-wired in parallel with this one with the EOL resistor at the furthest detector correct?

"Trying to get my hearing back in Houston"
Now hooking up the reversing relay so all sounders go off when one trips should be REALLY fun. In my sisters install I am not even going to use one. I put a few of those Piezo screamers BSR mentioned around the house and trust me, a few of those are louder than all the smokes going off. Those things will wake up your whole neighborhood, not just the block.
Thanks again for all of the help guys.

I'm not sure I'll need a reversing relay as I have the Elk voice speaker mounted about 12 feet up on a wall in my living room. This allows it to be heard throughout the house without any problem. In addition, I have a second speaker and red strobe outside overhanging my driveway so the neighbors get to experience the joys of having a neighbor with an Elk!

The only time (so far) that this came in handy was when my nephew left the house but didn't latch the front door well. In addition, he didn't arm the alarm. I was in Austin and 1/2 hour later when the system auto-armed (no motion in the house) it detected the wind-blown open door, set off the alarm and I received a message on my cell phone that the system was in alarm mode.

A quick call to the police verified that they were just passing by when they saw the strobe, heard the alarm and investigated. They shut the door and I was able to reset the alarm using ElkRP over the internet.

I love the piece of mind this system gives me!