How to wire a transformer into ELK zone to monitor AC Loss


Active Member
I've read about this method in a few posts, however they were from 2008, and I cannot find instructions anywhere on wiring a 12v wall wart directly into a Zone on the elk to trigger when AC power is lost. 
I understand the transformer will simply plug into an interruptable power source.  Also I believe the ELK can handle 2.2amps so anything under that would work.  Simply wire in as Normally closed, correct?
Does anyone have a resource on this to ensure i'm doing it correctly before I start?

Thank you!
Generally speaking I would think that a 120vac to 12 or 24 vdc transformer. Then connect the 12/24vdc to a spdt relay that is connected to an elk zone.
I'll bet that there are many here that have done similar and can help with details and parts.

Yes, I've read there is a 3 minute delay.  My backup generator will have kicked on by then.  I'm trying to get instant status on power failure, unless there is a newer method of detecting AC failure without the delay not discussed in earlier posts...
I also was under the impression the 12v wall wart can wire directly into the panel without a relay as long as it's under 2 amps... 
The inputs on the M1 actually produce a voltage that is used to measure resistance in the zone and determine if a contact is open or closed.
You don't want to connect the output of a wall wart directly to the zone input.  That could damage the M1.  
As Mike explained, you should use a relay.  Just make sure that the relay coil is matched to the type of wall wart you use. Some wall warts produce AC voltage, others produce DC voltage.  So you need to use a relay that as an appropriate AC or DC coil for the wall wart you choose.
I would prefer whatever route uses the least amount of power.  Does anyone have any hardware suggestions and where I can purchase online?  
The more I think about this, I have an extra ELK-930 doorbell sensor.  Couldn't I simply wire a 12v transformer directly into the doorbell sensor?  or even the ring detector?
I have one of these and 2 ring detectors lying around, could I utilize this somehow?

I'm thinking out loud here, but maybe the doorbell will fall into a trouble state since it's powered via a LV transformer.   If home to power is lost that transformer will fail to power the doorbell as well.  
I don't think the Elk 930 is a good solution for this problem.   The 930 is useful to detect when something (like the doorbell) is drawing power (900mA or more), but that isn't really what you want to measure in this case. It doesn't make sense to dummy up that kind of load just so the 930 can tell if the AC power is on.
One thought that occurred to me is to use the 930 to measure the load being drawn by the M1 from its transformer.  However, you would need to know that the M1 would always draw more than 900mA.   But I really don't like the idea of putting the 930 in the M1's power path.  The 930 was designed to detect momentary power draw, like you have with a doorbell.  Who knows if it would hold up under a continuous power load.  From a reliability point of view, I just wouldn't want to trust it.
If you want a simple solution that is pretty much off the shelf, I would use a 12V, 100mA wall wart, like this one along with an Elk 912B relay.  It will draw less than 2.5W, and will cost you just a few dollars in electricity over the course of a year.
If this were me, I would probably want to monitor that you at least are flowing current from the generator.   Maybe even see the status of the transfer switch.
That's the route I would suggest, assuming you have an auto transfer switch and the genset automatically runs...just monitor that for start, fail to run or whatever contacts the unit can put out.
Barring that, a RIB wired into any outlet or feed would be the way I would go, then drive the contacts to the M1. Better than using a transformer or other piece of hardware.
In reference to my post above, I remember looking into this before, however the only solution I was aware of is running a donut to monitor AC current.  It would be great if there was another solution.