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Thread: Keypad wiring redundancy

  1. #1
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    Keypad wiring redundancy

    We received this question from a customer, and thought others might be interested in this topic...

    Is it possible (or best practice) to loop back wire runs for keypads? The main intent would be to have a 'backup' run in the event the original keypad run wire gets damaged somehow (i.e. nail in the wall).

  2. #2
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    Ty,

    This is something that I have ran into a number times - particularly with installers who were use to doing keypad loops with Illumination. A lot of Illumination installers would loop back because the loops were limited in number so the wire runs typically would not get so long that a return trip was impractical. Since QS devices can be wired in a "topology-free" nature there is no reason that bringing the wire loop back to the head-end would be a detriment to the system. Having that extra wire is a nice backup and often is not as costly as other solutions (retro-fit wires, cutting walls open, or converting to wireless with transformer).

  3. #3
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    This is a good practice but make sure you don't connect both ends of the loop unless you disconnect the link in the middle. I have heard of this being done by accident and it caused communication issues on the link.

  4. #4
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    Quote Originally Posted by Chris Y. View Post
    This is a good practice but make sure you don't connect both ends of the loop unless you disconnect the link in the middle. I have heard of this being done by accident and it caused communication issues on the link.
    Yes, I can guarantee this to be the case. You'll get at best, "sluggish" response from the keypads. More likely LEDs chasing upward and spontaneous reboots of the keypads entirely. Having said all that, it's a great practice to create a return loop for servicing potential dead-shorts, etc.

  5. #5
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    Quote Originally Posted by Chris Y. View Post
    This is a good practice but make sure you don't connect both ends of the loop unless you disconnect the link in the middle. I have heard of this being done by accident and it caused communication issues on the link.
    Joining the ring can never be. In addition to the unstable operation may result in huge currents during a thunderstorm nearby. Always somewhere to be no cable is connected. This applies to all wires (com, +15V/+24V, mux, mux).
    I'm sorry for my english

  6. #6
    The loop back has saved us on a handful of times when a wire on the loop was cut, or when a customer wanted to add a keypad or two and the link was full ( in illumination). The extra cost of one more wire run is nothing compared to the headache if you get a wire cut in the middle of a keypad run.

  7. #7
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    Personally, I home-run everything and use a wire landing board. I would rather not have to deal with compromised wiring issues bringing down the entire loop, and wire is cheaper than labor (and extra labor in the wiring stage is cheaper than troubleshooting labor). Even with a loopback, you still have to take every junction apart to find and isolate the break - what if the data line is shorted by a drywall screw? A loopback won't fix that unless you take the bad stretch of wire out.

  8. #8
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    Quote Originally Posted by DHawthorne View Post
    Personally, I home-run everything and use a wire landing board. I would rather not have to deal with compromised wiring issues bringing down the entire loop, and wire is cheaper than labor (and extra labor in the wiring stage is cheaper than troubleshooting labor). Even with a loopback, you still have to take every junction apart to find and isolate the break - what if the data line is shorted by a drywall screw? A loopback won't fix that unless you take the bad stretch of wire out.
    If you're truly home running EVERY single keypad you either have a whole lot of WLBs or a VERY small number of keypads. Your point is not lost though, but if your loops aren't too big then finding where the the problem lies wouldn't take too much guesswork. As far as taking the bad stretch of wire out, I'll respectfully disagree. All you would need to do is disconnect at keypads on either side of problem, then connect the other end of the loop at the panel.

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  10. #9
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    Quote Originally Posted by whdigital View Post
    If you're truly home running EVERY single keypad you either have a whole lot of WLBs or a VERY small number of keypads. Your point is not lost though, but if your loops aren't too big then finding where the the problem lies wouldn't take too much guesswork. As far as taking the bad stretch of wire out, I'll respectfully disagree. All you would need to do is disconnect at keypads on either side of problem, then connect the other end of the loop at the panel.
    You have a point. Most of my wired jobs are pretty small. Five years ago I was doing nothing but new construction, nowadays it's mainly renovations, and my stuff is mostly wireless, so I can get away with home runs on the few wired devices. That said, even on older Interactive jobs, I tried to keep my keypads home run, or at worst a loop per room. And yes, it is WLB intensive, but I have found the troubleshooting so much easier when something goes wrong and you can isolate one or two KPs at a time.

    And by "taking out a bad stretch of wire," I meant disconnecting it at the keypads on either end, like you said :), not actually ripping it out of the wall. I am primarily a programmer, and the less I have to do with removing devices from the wall and the more I can leave that to my installers, the happier I am, so my thinking runs that way. But too many times I've been called to fix a "program glitch" and it was really in the wiring or hardware. The easier it is for me to deal with those without having the resources of a truck full of install equipment, the better.

  11. #10
    Thanks for the post. It was pretty interesting.

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