Two relays off one output

arctec37 · Sep 17, 2020

I ran into a problem which may be my own doing. had a 912 relay about 75 feet from the panel and used an output to trigger it. The wiring is standard alarm wire so I am assuming I had a voltage drop and increase in current. I am trying not to have to snake new wire so I am thinking of putting a 912 relay by the M1 panel connected to one of the outputs say #12 and from that relay connect a 12v power supply to trigger the 924 relay 75' away. That way I will not be taxing the panel due to voltage drop. The 924 relay 75' away is powering a 120v outlet.

Any thoughs????

LarrylLix · Sep 17, 2020

Extra conductors in the cable? Double up the copper.

Solid state relay with a more sensitive input/coil?

RAL · Sep 17, 2020

You say you ran into a problem, but it's not clear to me what your problem is. You could certainly use one relay driven by the M1 to activate a second relay some distance away, but I'm not sure that's necessary.

The 912 relay draws 30mA. An M1 output can provide 50mA, so you're ok there. 75 feet of #22 alarm wire will create a voltage drop of about 0.07V. Pretty insignificant.

The wire length does not cause the relay to draw more power. Rather, it causes voltage drop, which, if it becomes large enough, may reduce the voltage that the relay sees to a level below what is required to activate it.

If you are going to control a 120VAC outlet with a relay, I would not use a 912 or 924. It creates problems on how to mount and house the relay itself, and isolate the low voltage wiring from the AC wiring. It's easy to end up violating the electrical code this way.

Instead, use a RIB relay, like the RIBU1C. It will mount to a standard electrical box knockout, and is UL approved for this purpose. The coil can be activated by either low voltage DC or 120VAC. Plus, it only draws 15mA.

arctec37 · Sep 18, 2020

The problem is .... I used output 7 to trigger a 912 relay about 75' away. worked fine for about 6 months. Then the output stayed energized no matter what the rule or the keypad said. The keypad would show the output off, all software would show the output off but it was energized. Wasn't sure what happened but decided to move it to another output #15. It worked for about 4 months and then the same problem. Keypad shows the outputs off but now #7 & #15 are always energized. I was able to speak with ELK technical support and they thought it was to much of a run for the panel outputs to handle with 22 ga wire. We even defaulted the panel and those two outputs were still energized. so I figured if I should not try the same thing on a different output and expect a different result. I did put the 912 relay in its own box but your suggestion on the the RIBUC1C is a much better solution no question about code compliance. I am controlling a GFI outlet that turns on and off the outdoor landscape lights every night according to dusk and schedule. So just to not stress the panel I thought of mounting a 912 relay inside the panel enclosure that is triggered by and output. The 912 relay would control a 12v wall transformer next to the panel that would trigger the RIB relay 75' away at the landscape lighting outlet. This way I believe the panel outputs are protected.

Thoughts????

RAL · Sep 18, 2020

arctec37 said:
The problem is .... I used output 7 to trigger a 912 relay about 75' away. worked fine for about 6 months. Then the output stayed energized no matter what the rule or the keypad said. The keypad would show the output off, all software would show the output off but it was energized. Wasn't sure what happened but decided to move it to another output #15. It worked for about 4 months and then the same problem. Keypad shows the outputs off but now #7 & #15 are always energized. I was able to speak with ELK technical support and they thought it was to much of a run for the panel outputs to handle with 22 ga wire. We even defaulted the panel and those two outputs were still energized. so I figured if I should not try the same thing on a different output and expect a different result. I did put the 912 relay in its own box but your suggestion on the the RIBUC1C is a much better solution no question about code compliance. I am controlling a GFI outlet that turns on and off the outdoor landscape lights every night according to dusk and schedule. So just to not stress the panel I thought of mounting a 912 relay inside the panel enclosure that is triggered by and output. The 912 relay would control a 12v wall transformer next to the panel that would trigger the RIB relay 75' away at the landscape lighting outlet. This way I believe the panel outputs are protected.

Thoughts????

It's difficult to explain why the two outputs would fail. The 912 relay shouldn't be a problem in terms of current draw. The resistance of the wire run to the relay would reduce the current load on the output. And the coil has a snubber diode that prevents inductive spikes from harming the output.

Does the 75' of cable run outside at all?

If you want to take a low risk approach and reduce the chance of damaging any other outputs, I would use an Elk 924 relay instead of a 912. The 924 has a separate input trigger and gets its power directly from the AUX power terminals, so the coil is not driven by the output directly.

The rest of what you propose sounds fine, using a relay close to the M1 to control the RIB relay.

LarrylLix · Sep 18, 2020

arctec37 said:
The problem is .... I used output 7 to trigger a 912 relay about 75' away. worked fine for about 6 months. Then the output stayed energized no matter what the rule or the keypad said. The keypad would show the output off, all software would show the output off but it was energized. Wasn't sure what happened but decided to move it to another output #15. It worked for about 4 months and then the same problem. Keypad shows the outputs off but now #7 & #15 are always energized. I was able to speak with ELK technical support and they thought it was to much of a run for the panel outputs to handle with 22 ga wire. We even defaulted the panel and those two outputs were still energized. so I figured if I should not try the same thing on a different output and expect a different result. I did put the 912 relay in its own box but your suggestion on the the RIBUC1C is a much better solution no question about code compliance. I am controlling a GFI outlet that turns on and off the outdoor landscape lights every night according to dusk and schedule. So just to not stress the panel I thought of mounting a 912 relay inside the panel enclosure that is triggered by and output. The 912 relay would control a 12v wall transformer next to the panel that would trigger the RIB relay 75' away at the landscape lighting outlet. This way I believe the panel outputs are protected.

Thoughts????

Unless a relay is specially designed for DC coil operation, it's core can become magnetised and the armature never dropped out, or clings in for long durations before dropping out.

Usually the armature in a true DC relay has some copper or non-ferrous metal to magnetically insulate the armature from the central core. This breaks the magnetic loop and stops the phenomenon from happening.

Also try wiping under the armature clapper with some varsol or other solvent as the coil pole and contact surface may have become gummy from heating the oils used in production of the relay decades ago. We yoost2 use a very thin hacksaw blade with a towelette wrapped around it with some solvent on it. If the gap is very thin, get somebody to hold it for you while you hold the edge of a paper towel taught. Wet the paper with some solvent and use a sawing action to wipe inside the armature gap. The helper can apply slight pressure on the armature to tighten the wipe pressure.

Wipe other armature contact and pivot surfaces with 70-100% alcohol and no lube to get sticky later. Contact cleaner is good if you have it.

RAL · Sep 18, 2020

LarrylLix said:
Unless a relay is specially designed for DC coil operation, it's core can become magnetised and the armature never dropped out, or clings in for long durations before dropping out.

Usually the armature in a true DC relay has some copper or non-ferrous metal to magnetically insulate the armature from the central core. This breaks the magnetic loop and stops the phenomenon from happening.

Also try wiping under the armature clapper with some varsol or other solvent as the coil pole and contact surface may have become gummy from heating the oils used in production of the relay decades ago. We yoost2 use a very thin hacksaw blade with a towelette wrapped around it with some solvent on it. If the gap is very thin, get somebody to hold it for you while you hold the edge of a paper towel taught. Wet the paper with some solvent and use a sawing action to wipe inside the armature gap. The helper can apply slight pressure on the armature to tighten the wipe pressure.

Wipe other armature contact and pivot surfaces with 70-100% alcohol and no lube to get sticky later. Cotact cleaner is good if you have it.

The stuck outputs that the OP has are voltage outputs rather than relay outputs. I don't believe he has any issues with the relays themselves sticking. The Elk 912 relays are designed for DC and are totally enclosed, so there isn't much you can do in terms of cleaning them.

RAL · Sep 18, 2020

If you aren't already using Output 3, which is a relay output, for anything, you could use that instead of an external relay to control the RIB.

Two relays off one output

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