Elk Relay Wiring

I have all my Elk components and just finished wiring my first sub panel with my exterior relays. I'm not sure if the way I wired it is going to work but it made perfect sense to me. Here is what I have.

I have my M1RB relays controlling/triggering 912 relays with a dedicated and controlled 12V power supply through a P212S. I have 16 912 relays in a sub-panel that will control low voltage lighting and sprinkler valves. Running to the sub-panel from one of my Elk panels are 2 9 conductor 18 gauge cables. All the (-) are combined off the M1RB into a single conductor. I plan on using one condcutor for the common (-) and 16 of the other conductors for the voltage (+).

Once I get to my sub-panel I have the common run to my first relay and then simply jump from relay to relay connecting the (-). I also looped the last relay (-) back to the single conductor (1) coming into the panel. I assume this going to work since all the (-) are the same. Is this correct?

The (+) are wired individually to each relay that they control.

Thanks

Why the 912 relays? I have my sprinkler system running directly off of the m1rb relays. I daisy chained one wire off the 24vac transformer across the common terminals of the relays and then put each valve lead to the NO side of each relay. All of the ground wires to the valves come together in one wire and are spliced to the other side of the 24 vac transformer.

And, if it is more convenient, you can run a cat 5 wire to where it is more accessible to the sprinkler valve wires and put the m1rb there. Of course, the m1rb is not weather rated so it needs to be indoors or in a weatheproof enclosure.

You won't need a p212s unless you have a lot of stuff. The built in power supply is pretty stout. You can look up the specs on that but my system has 5 keypads, 3 zone expander, 3 m1rb's, a siren, a spekaer, and an m1xep and that doesn't exceed specs.

Due to the layout of our house and size of the yard, I had to locate the relays outside. I didnt want to run the bus ouside so I kept the bus indoors and built three sub panels with relays and placed them around the perimeter of the house.

This was a bit more expensive but in the end I think I will be better off. The reason I am using the P212Ss is that I have a lot hanging off the M1. The 912 relays are triggered by a 12V Elk transformer unsupervised through the M1RB. The p212S is for the boards and components hanging off the M1.

I also didnt want to run all the sprinkler wires to a central point in the house. In addition, I have 3 transformers controlling lighting where I had to worry about voltage drop over the length of the lines so I kept everything outside.

So it sounds like you can daisy chain the common wire across all the relays?

Thanks

You are daisy chaining the "hot" wire across the relays. In this way, when the relay closes, the wire to that valve becomes hot.

The commons all come together and get hooked directly into the 24vac power supply. It is all somewhat academic since it is AC current, but typically each valve has one lead connected to a common that daisy chains around the yard terminating in the common on the power supply. A second wire that is unique to each valve goes back to the controller for connection to the 24vac hot via a switching relay.

I think you would be better off if you centralized all your controller or at least moved your m1rb's into your water proof outdoor enclosures and ran a cat5 from those relays back to the Elk's dbh. Having a relay run a relay just seems like poor form to me.

I have a 16 zone system and 1 acre of grass and I ran the sprinkler control wires to one spot where I have the two Elk relay boards which are hooked back to the Elk via Cat5.

Since you are locating your relays scattered about the yard, do you have multiple 24 vac transformers at each relay location? And if you are doing it that way, do you have the common wires from your valves separate. I don't know if I would have multiple 24vac power supplies share the common wires.

This was a hot topic when the OP was first figuring this out... because of the nature of his design, it was a shared opinion that this "doubling up" of relays was the smartest way to go. It ensures that if someone or something screws with his outdoor enclosures, they don't knock out his entire databus causing an alarm condition. If it's tampering that may not be a bad thing, but if it's a hungry squirrel, it's not worth calling the cops over.

I don't understand what the value of having the relays in various locations scattered about the yard is. every single valve in the yard still has a unique connection from the m1 relay board all the way to the valve. the only thing you're saving is the common wire. but now you have to have multiple power supplies at each set of relays located in yard. I would also be concerned about having multiple power supplies if you are still having all the valves common wires hooked together electrically.

if you are going to put them scattered about the yard, you need to put them in the waterproof screwed lid plastic j boxes. no squirrel is ever going to get inside of 1 of those.

The OP was doing some tricks with both low voltage lighting scene control as well as sprinklers. He indicated that there were 3 logical groupings where he had both lights and sprinklers that he wanted to control. Because he was concerned with voltage drop and also didn't want to buy multiple transformers, he went the relay route. The doubling-up of the relays provides protection of the M1's bus against tampering, animals, environmental issues, and electrical issues (lighting, etc).

It's what made sense to the OP. Personally I keep the transformers and sprinkler controls inside but the OP had his reasons for doing what he did.

There can be some value in doubling up on relays for isolation and surge protection also.

gatchel said:

There can be some value in doubling up on relays for isolation and surge protection also.

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Agreed. I have done this in some situations where I needed to utilize some isolation. I have seen relays go bad and drop 110VAC through the coil and back to an HAI panel. Let out the magical smoke and the whole board had to be replaced.

Don't get too comfy thinking the extra relay will block a ligtening strike. Those relays have like a 1mm gap. Lightening voltages will just arc across it. Relays are not lightening arrestors.

The only time I have seen someone use two relays is when the first relay is not rated for the power needed. Sprinkler is only 24 vac, low current. I have something on the order of 2000 feet of sprinkler system wire in my lawn. I even accidentally turned on all of the zones at once (16 of them, but actually 17 valves since two valves are on one zone) and even with that current draw they all had enough juice to turn on. But whatever, aside from having twice as many things that can fail and extra money/work of install, it will all end up working the same.

Lou Apo said:

Don't get too comfy thinking the extra relay will block a ligtening strike. Those relays have like a 1mm gap. Lightening voltages will just arc across it. Relays are not lightening arrestors.

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Nothing will stop a lightening strike, I agree. That's why I used the word surge.

One would have to admit that if "something" happened at the remote relays' controlled device, having the extra relay in the way of the other relays on board with the databus and other "more sensitive" components, would lessen the possibility of that same "something" affecting the M1OVR or other components on the databus.


If it were me I might have done it the same way. I would definitely install surge protection on any wires that enter the house, even if they are just a voltage source to control another remote relay.

I'm pretty sure lightening is the only thing that could cause a destructive surge on a sprinkler system wire. The relays on the Elk are rated for 120 v 10 amps, so even accidental wiring to line voltage would not hurt the Elk. And a surge on the line that significantly exceeds that would damage that individual relay and end there unless it was a huge surge. In other words, the surge would have to exit the contact portion of the relay and arc over to the coil, a definite possibility with lightening, but not much else. If you are worried about a burgler purposefully brining some big gun capacitor and unloading it on your sprinkler wire to fry your alarm, you need to consider what it is you have in your house that a crook of that caliber would want with your house! h34r:

If you actually want to protect your stuff, I would suggest rf controlled relays. It would be impossible for anything on the spinkler system to get back into your house via that route. Plus, no drilling holes from inside to outside.

http://cgi.ebay.com/RF-Wireless-Relay-Remote-Controller-8-channel-Module-/390196804310?pt=LH_DefaultDomain_0&hash=item5ad98abad6

Or you could use the CIA webcontrol device being discussed in another thread up to a wireless access point. Trouble is an Elk doesn't have the ability to interact with one of those directly as far as I know.

This would actually electrically isolate the systems.

In 15 years of doing access control and CCTV I have seen some very interesting, unexplainable failures, Not a storm to be found...

I like the wireless option except for the fact that a standard meter can't test wireless. Wireless is great when and if it works.

I also tend to stay away from off brand devices that I expect some reliability out of, or support if there is an issue.

With 912's being about $6 to $7 each in 12 packs, the cost really isn't that much more. To surge protect the same 18 gauge cables with Ditek 4LVLP devices you could easily spend $150 to $200 depending on where you get them.

Except a 912 relay isn't a surge supressor. A lightening strike will pass right through it, perhaps melted and on fire, but still passing high voltage current for a few thousandths of a second.

I actually have a good use for those ebay rf relays so I bought one. If it works as well as my "made in China" keyfob rf relay we will be in business. My keyfob hasn't failed in 2.5 years so, we'll see.

With a "hold on/release off" rf relay, it can't get stuck on, so you are unlikely to have a disaster (like the sprinkler being stuck on for a few days). Anyway, I expect to have the relay in hand in maybe 10 or 14 days and will let you know how it works.

Lou Apo said:

And a surge on the line that significantly exceeds that would damage that individual relay and end there unless it was a huge surge. In other words, the surge would have to exit the contact portion of the relay and arc over to the coil, a definite possibility with lightening, but not much else.

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The failure I mentioned was line\110VAC off an evap. cooler. It happens...