Alarm in a detach garage

Quick question. I'm planning for the alarm in my garage and I have a simple question.

I have a M1 Gold system and in order to protect / monitor my garage with the same system what would be the ideal way. The garage is about 150 feet from the alarm panel. I have a 4 inches conduit from the house to the garage.

Can I simply put a enclosure in the garage with a ELK-M1DBH to extend the databus to the Garage then connect my keypad and a ELK-M1XIN for the local zones?

Any other suggestions?

Yup. You need to consider overall databus length - 150ft is nothing, but it might make sense to do two separate legs - one for the house and one for the garage, rather than a giant loop.

The databus hub is not required to extend the bus to distant keypads and expander boards. However, it helps to simplify wiring because it transforms the logical bus into a physical star topology. In your case, I'm not certain it offers a tremendous advantage.

Using a databus hub, you'll need to pull two CAT5 cables through the 4 inch conduit, one for the keypad and the other for the expander board. Plus, because of the wiring scheme employed by the databus hub, the overall bus length is actually twice the physical distance of each connected device (1). If you don't get the databus hub, you'll need only one CAT5 cable to the garage. Your choice.


If you plan to install many sensors in the garage, having a local expander board is a good idea. If you don't foresee more than a few sensors, you can simply run two CAT5 cables and wire the sensors (4 pairs in each cable) and keypad directly back to the M1 in your house.

(1) The bus wire goes from the hub to the remote device and then back to the hub. 150 feet x 2 = 300 feet. It then proceeds to the next device and returns back to the hub (150 feet x 2 = 300 feet). So in your case, to wire the expander board and keypad with a hub, it will extend your existing bus by 600 feet. From the Databus Hub Manual:


Maximum "TOTAL" Length of the M1 RS-485 Data Bus should NOT exceed 4000 feet.
When calculating the total length, figure the length of each home run to the M1DBH times 2 (x 2)
since the data lines run out and back. Maximum number of data bus devices varies by control.)

Do you already own a DBH or do you plan on buying one for the project?

Judging by the conduit comment I assume that the garage is detached. Are you going to use any surge protection?

As alluded to above, if you have fire alarm involved and you are extending data between buildings, although many don't enforce it, surge/lightning supression is mandated by code, however it's a smart idea irregardless.

In the case of installing remote bus devices, I would recommend installing a separate power supply and only run pure 485 and a common negative back to the panel rather than limit yourself to the single cable and voltage drop you're going to see by daisying bus devices in the field. The M1 doesn't like it when the bus device voltage starts to sag and ugly things happen when expanders and similar reboot from lack of proper voltage.

I would not see a benefit to running multiple bus wires out there when a single would suffice and keep the total length to a minimum, unless you need to bring devices back to the panel for some purpose. This is why I would strongly recommend adding an aux supply, run enough cabling for a 485 feed/return and a common panel negative and call it a day.

123 said:

Using a databus hub, you'll need to pull two CAT5 cables through the 4 inch conduit, one for the keypad and the other for the expander board. Plus, because of the wiring scheme employed by the databus hub, the overall bus length is actually twice the physical distance of each connected device (1). If you don't get the databus hub, you'll need only one CAT5 cable to the garage. Your choice.

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That doesn't make any sense. Regardless of whether or not he uses a DBH in the garage, he only needs a single Cat5 out there. If he wants a keypad, he can run that off the DBH. ***Re-read your post - I think you're saying that if he uses a DBH in the house, he needs two runs - but that's simply not true - you can daisy chain devices off a leg of a DBH run - Elk even has an example doc on this (which I found a few years after I started doing it anyways) that clearly shows how it's done. Once you get the concept of the send/receive pairs, it makes total sense how to daisy chain to complete the loop. I just found the doc and will attach it.

I do the sub-panel thing in my garage and use just the single Cat5. I don't bother with a DBH out there, even though I have one in my main panel. It's very easy to loop in several devices without the DBH and save some space - all off a single leg of the primary DBH.

I do agree with DEL on the two points of using surge protection if going in the ground; and also the aux power supply to prevent issues with voltage loss over distance - remember to size your remote supply and battery to at least minimally outlast the primary.

How many zones and what are they that you want to monitor in the garage?

Work2Play said:

That doesn't make any sense.

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<sigh>


There's nothing in my original post that would lead the OP astray, waste time, effort, or money. The suggestion I posted is based on practicality and is, contrary to your conclusion, a sensible solution.

My example assumes the databus hub will be located in the OP's house and two cable runs to the garage offer maximum convenience.

The databus hub is a convenience device. We all know we don't need it to wire keypads and expanders in a daisy-chain. But we buy it to organize the connections into a star. Yes, individual points of the star can have multiple devices thereby creating a hybrid physical star and bus. However, it diminishes the convenience of a true star. For the miniscule cost of a second cable, the OP retains all the benefits of a true star.

Can he wire the garage's expander and keypad on a single run back to a databus hub? Sure. Using two runs? Yes. He can also use a single run without a databus hub. It all depends on what level of convenience he desires when it comes time to add devices to the bus.

To play devil's advocate with the last couple of posts,

in the case of a second building and maintaining a bus topology, with simplicity in mind, I'd honestly give the advice to split the house onto it's own leg and the outbuilding on it's own leg, each terminated appropriately. In this case, it would make installing more bus devices easy, barring changing any termination changes (doubtful if it's done properly) and allows the easiest troubleshooting approach and methods. All the DBH does is provide a way for a novice to maintain easy 485 wiring methods without hard splicing the bus together, it doesn't change the topology into a star, the only device that does that is a DBH-R, and it only splits it into 4 branches per installed hub.

As long as any future bus devices are cabled in a minimum of 6 conductors, it makes 0 difference on what topology is run and no modifications would be changed in regards to the terminating resistor.

I wouldn't waste the energy pulling a second cable for anything but a spare, it's simply not needed nor really practical if you split the bus into 2 branches, single one per building.

Thanks for all the feedback. I was mainly checking if this was ok to run the second leg from the M1 to a DBH that would be installed in the garage. Then install a M1XIN on the DBH as well as the keypad and UltraProx Reader. I'm planning for Motion, glass break, fire, 2 IR sensor and hand full of contacts.

I already have a DBH for the house and just for simplicity I was thinking to put all the garage related stuff in it's own enclosure in the garage. Of course the garage would have it own power source and surge protector.

I have a bit of time before I start to frame the garage as I currently only have the various conduits installed from the house to the future garage location.

If these things would be IP it would be easy as I'm pulling a fiber between the buildings but it's not the case.

Is there a max distance of wire between the panel and a sensor? Maybe I can pull each wires from the house to the garage as an option. Would this affect reliability?

Again thanks for all your feedback.

Two legs; sounds clean and simple.

RE: " it doesn't change the topology into a star,"
The databus hub retains the M1's logical bus topology but manifests it as a physical star topology. Using Ethernet as an example, it is a logical bus topology that, with twisted-pair and hubs and switches, is manifested as a physical star topology. For an example of Ethernet as a physical bus topology, we need to look 1back to the olden days of "Cheapernet" or the even older days of "Frozen Yellow Garden Hose".

The first network I installed and managed was Cheapernet (1987). What a headache to manage a physical bus of 50 stations. About three years later, I converted it to "star-like" Ethernet through the wonders of twisted-pair wiring, hubs, and a single, very expensive, switch.

I've gone back to the old 10base networks, the thinnet and thicknet and IBM with the vampire taps.....but I digress.

If the bus is split into 2 legs, each with it's own hub or physical wiring connections, it'll be done, barring any power requirements for the remote leg. In this case, sensor wiring distances would be a non-issue. If you start pulling multiconductors with sensors back to the panel more considerations would need to be factored in, such as voltage drop, total loop resistance and further increasing the likelyhood for surge and lightning damage vs. installing a protector on a single cable, you'd be looking at multiples to be practicable.

I wouldn't go through the effort in futility of pulling everything back to the panel if a simple expander would limit the amount of conductors needed. Think smarter instead of working harder. Simple subpanel, then you're done.

Maybe I should have said "that doesn't make any sense _to me_". Which is why I put the line about re-reading your post.

So while technically correct, running a second wire is easy enough in concept, it is another wire that needs surge protection, and it also adds 300ft to the bus unnecessarily. It just doesn't seem like the preferred way... Or rather, it's certainly not how I'd do it or recommend others do.

Beaumeri said:

... run the second leg from the M1 to a DBH that would be installed in the garage. Then install a M1XIN on the DBH as well as the keypad and UltraProx Reader. I'm planning for Motion, glass break, fire, 2 IR sensor and hand full of contacts.

Click to expand...

Good plan; you certainly have a sufficient number of sensors to merit an input expander in the garage.

Maybe I can pull each wires from the house to the garage as an option. Would this affect reliability?

Click to expand...

Given two or three sensors and a shoestring budget,this is an option. In your case, the input expander is a better solution.

...the garage would have it own power source and surge protector.

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I assume the AC mains to the garage and house have a common ground?

+ 1 on Dell's recommendation for surge protectors, you won't be sorry. If it were me I would do both sides.

Sent from my Galaxy Nexus