remote controlling a light (130 ft)

Discussion in 'The Projects Forum' started by okred, Dec 10, 2014.

  1. okred

    Thread Starter New Member

    Dec 10, 2014
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    This project involves controlling a parking lot type light (150W) from either of 2 locations; One near the power source and light fixture (<25') and one approx 130' away. Doing conventional 3 way switch system would require running romex the 130' which presents significant other physical issues.
    Typical wireless (rf) remote control systems I have located so far cannot reach the distance.
    There are already unused cat 5 wires in place. What I would like to do is find an inexpensive 'contactor' device that could be controlled via the cat 5.
    Two local electrical suppliers weren't much help; (maybe I don't know the right terminology or questions).
    Can someone tell me if such a device exist; Where to get it or possibly how to build one using a 'cube' relay.
     
  2. Brevor

    Active Member

    Apr 9, 2011
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    Yes it should be easy to do with a cube relay. What voltage does the parking lot light require?
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I highly suspect local/national electrical codes will come into play here..
    Are you capable of determining if the solutions provided here (mostly a DIY forum) will meet code?
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I assume you have a power source where you want the lamp.

    Also, do you have a source of 12 volt power for your low-voltage (cat5) signaling system to activate the relay?
     
  5. okred

    Thread Starter New Member

    Dec 10, 2014
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    Thanks for the response;
    The light requires 120V, has 150W bulb. I just know the funamentals of a cube relay... Have the 120V power close by; would have to come up with the LV DC for the relay...????
     
  6. okred

    Thread Starter New Member

    Dec 10, 2014
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    Good point. Probably so. When I built a vacation house in rural Colo. the county allowed me to do the wiring as long as it met code; I managed that with minimum hassle/redo. I still have access to NEC. This project is on a barn, 20' from ground, zoned agricultural,
    + I have a long time friend who is an inspector in a nearby community; He will help keep me in line.
     
  7. okred

    Thread Starter New Member

    Dec 10, 2014
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    Thanks for your response.
    The light will be mounted on the side of a barn. There is 120V available. Haven't resolved the 12V DC issue. Hope to find an inexpensive LV unit rather than build one (dont really want to get into stepdown Xformers, diodes, etc.)
     
  8. #12

    Expert

    Nov 30, 2010
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    120 VAC to 12 VDC switching supplies are very easy to find. On the other hand, using an AC relay will solve all that, "How do you get DC?" bologna. Any air conditioning guy could build this out of the back of his truck as a 24 VAC circuit.
     
  9. BillB3857

    Senior Member

    Feb 28, 2009
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    A local water company uses this for remote control..
     
  10. John P

    AAC Fanatic!

    Oct 14, 2008
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    It seems to me as if you can do this easily, if you have a low voltage power source available. All you need to do is set up a conventional 3-way switch system, but one of the "switches" would actually be a relay, controlled off your low-voltage supply over the Cat-5 cable. So you can switch the light on from the house and then off at the barn, or whatever you need to do. Hopefully it's not a problem that the relay would sometimes need to stay on all the time, even when the lights are off. Would it help if the power for the relay could come from the remote end of the wire? That would work equally well.

    I think you could also rig it up with pushbuttons at the two ends of the wire, with a "lights on" and a "lights off" button in each place, and power supplied from whichever end of the line was most convenient.
     
  11. ebeowulf17

    Active Member

    Aug 12, 2014
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    Why not do standard 3-way switch wiring on the low voltage side, with the relay coil as the load, which then switches the high voltage light? Then the relay is only on when the light is on.

    Also, am I remembering correctly that voltage drops and wire gauge requirements relative to wire length scale much more dramatically for DC than AC? If so, that might be a good reason to keep the low voltage side AC instead of DC on a long run through very small gauge wires.
     
  12. John P

    AAC Fanatic!

    Oct 14, 2008
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    A fine big "duh" from me there. Yes, use 2 switches at low voltage and make the relay coil be the "load". In fact, if all the relay has to do is switch the light on and off, it can be a solid-state type that draws very little power, and isn't at all fussy over how much current the low-voltage side is getting. So there wouldn't be much voltage drop in the Cat-5, and if the current is affected, it shouldn't be an issue. By the way, note that the current flows through the Cat-5 whenever the relay operates--it uses different conductors according to the setting of the switches--so you could allow for the wire resistance in setting up the circuit. Though I think the Cat-5 resistance would be small compared with other resistance in the system. Spec seems to be 28.6 ohms per 1000ft, so 300ft of the stuff (150ft out and back) is less than 10 ohms.
     
    Last edited: Dec 14, 2014
  13. okred

    Thread Starter New Member

    Dec 10, 2014
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  14. okred

    Thread Starter New Member

    Dec 10, 2014
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    1. OK, I appreciate everyone's help. Thought I had it under control. Bought an IDEC RR2KP-U Latching Relay and a Transformer to supply the 24VAC(mainly because that was what the supply house had in stock). Got home before another big DUH moment. Thought I could figure out the little schematic printed on the relay case; I need help connecting the dots. Attached is a cy of the relay schmatic; Can someone help me get the right wires to the right lugs?
     
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