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One Pump, One Pump Start Relay, and 2 Controllers

Discussion in 'Irrigation' started by MEXANDME, Mar 29, 2013.


    MEXANDME LawnSite Senior Member
    Messages: 396

    I am in the process of replacing a very old RB controller. It is a RC 7-A with the push-pull pins. It activates a pump start relay that turns on a deep well 220V pump. The controller, PSR, and pump are all at the same location.

    The pump / PSR is also activated by a RB ESPM controller that is about 200 feet away for another system. Apparently there are two conductors getting from the distant controller (ESPM) to the RC 7-A controller. The reason I say "apparently" is because there is quite a "spider web" of wires in the RC 7-A controller cabinet.

    My question is this. There is also a low voltage relay wired into this "spider web" that, being the novice that I am, I do not understand. Do I need to keep the relay or can I just terminate all 4 leads ( 2 ea MV and 2 ea Common) directly to the PSR?

    I am just trying to understand what my options are before I dig into the "spider web."

    Thanks in advanced for any assistance!

  2. greenmonster304

    greenmonster304 LawnSite Gold Member
    Messages: 3,681

    It sounds like you have an isolation relay in there. There should be two. I had this situation last spring http://www.lawnsite.com/showthread.php?t=376053&highlight=Spring+surprise

    MEXANDME LawnSite Senior Member
    Messages: 396

    304.............It is interesting that you mention that there should be two relays. There is the one that I mentioned in the original thread that is wired in in the RC 7-A cabinet AND there is one laying in the ESPM cabinet but not wired in. It's an old relay just laying in the cabinet. It appears that it used to be wired in. It looks just like the one in the RC 7-A cabinet.

    Can I just eliminate the one in the RC 7-A cabinet altogether? Or will that cause a backfeed, voltage drop, etc. situation?

    Thanks for help with this. I am out of my league on this one!


  4. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,318

    Hunter, Rainbird and Toro have online wiring diagrams for multiple controllers, PSR etc.

    Sorry i dont have a link
    Posted via Mobile Device
  5. greenmonster304

    greenmonster304 LawnSite Gold Member
    Messages: 3,681

    The problem I was having was that the Total Control was back feeding a I Core and causing errors. You should hook them back up.
  6. Sprinkus

    Sprinkus LawnSite Silver Member
    Messages: 2,310

  7. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Silver Member
    Messages: 2,144

    I don't have a copy here at home but at the office I have an older Rain Bird technical manual that shows the correct wiring so that two controllers can operate one PSR. You do need two smaller relays to keep the controllers isolated from each other. When I get into the office on Monday I'll have to pull it out and scan it for you. It's a handy piece of reference to have. The two smaller relays are only about $25 each.
  8. cppendergrast

    cppendergrast LawnSite Member
    Messages: 107

    You might find a product called an Isolator that only requires one for two controllers.
  9. HunterTekGeek

    HunterTekGeek Sponsor
    Messages: 326

    I agree with the other posts suggesting you contact your irrigation manufacturer for an isolation relay schematic. If you back-feed the RC-7A with 24 VAC through the Master Valve circuit (from the other controller) it will activate the rapid advance motor, click over to Station 1, and start the controller.
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,599

    One of those happenings that make the poor installers tear their hair. :help:

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