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Electrical Troubleshooting / "Crossed" Wires

Discussion in 'Irrigation' started by jb925, Sep 19, 2013.

  1. Stillwater

    Stillwater LawnSite Platinum Member
    Posts: 4,834

    This is a major hint for everyone if not a hint it should get the brain thinking in the right direction

    P=VI and V=IR therefore P=(IR)I P=I^2 R
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  2. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,436

    That's pretty harsh Stillwater, look at the beginning of this thread.

    Went out to a commercial site where station number 5 was not turning on.
    I turned on station 5, manually from the timer, to find that station 3 was turning on. I moved on to turning on stations 3 and 4, and again, station 3 was turning on.

    I connected a toner to station wire 5, at the valve, and found that the wire connected to wire terminal 5 was the loudest. Did the same for station 4, and again, the loudest wire was the wire connected to wire terminal 4. Proceeded to tone station wire 3 and found that I was getting loud tones from multiple wires.

    Moved on to the mutimeter to see what I could find. Manually turned on station 3 and found (at the timer wire terminals):
    Station 3: 26 volts
    Station 4: 16 volts
    Station 5: 16 volts
    Station 8: 16 volts
    Station 10: 16 volts
    Station 11: 16 volts
    Station 12: 16 volts

    I removed station wire 5 from the terminal and touched one lead onto the terminal, nothing. Removed the lead from the terminal and touched the wire and found 16 volts coming FROM THE WIRE.

    Moved on to manually turning on station 4 and I got 26 volts from terminal 4, yet again, 16 volts coming from stations 3, 5, 8, 10, 11, 12. I am getting the proper voltage for the station I manually turn on, but the rest are returning 16 volts.

    I disconnected station wire 3 from the terminal and found that even though the wire was disconnected, when the other stations in question were manually turned on, here was station 3 turning on still.

    In valve boxes for valves 3 and 5, I found a red wire that came up under the valve, into the box where it was coiled, and leaves the box without any kind of connection to the solenoids.

    I also used a valve activator to test the solenoid and all stations in question turn on as they should when using the valve activator.

    Ive heard this referred to as "crossed" wires, where a station wire is making contact with one or more other station wires and causes this type of problem.

    Anyone have any thoughts or suggestions?
    I tried searching the forum but no luck.
    Thank you.

    The OP isn't inept, he's just out of his comfort zone.
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  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,685

    So exactly what do the readings of 16 volts indicate?
  4. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,436

    I made a huge mistake for which I apologize, I copied and pasted the OPs first post as an example of how his efforts to troubleshoot using voltage alone are in vain. I thought that all that were following this thread would understand what I was doing. ML has already given me a chewing out but he now knows what is going on. Again, I apologize for being misleading, it was unintentional.
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  5. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,436

    Ok, I hope that the confusion doesn't slow the momentum of this thread.

    Now if I may,

    If your resistance of a zone is 15 ohms.
    Your voltage measures 27.2 vac.
    The amperage measures .628 mA

    What do these measurements tell you about the zone?

    I told Stillwater and ML already so they can't play.
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  6. Cape Atlantic Landscaping

    Cape Atlantic Landscaping LawnSite Member
    Posts: 37

    OK I will play

    Jim my best educated guess would be more than a multi valve circuit

    1. 15 ohms of resistance with a multi valve circuit is ok because of the more wire path it must take through the circuit
    2. 27.2 Volts is acceptable voltage at the controller
    3. .628 amps to me looks like 3 valve circuit

    I am only guessing but that's why we are here to learn
  7. Cape Atlantic Landscaping

    Cape Atlantic Landscaping LawnSite Member
    Posts: 37

    correction a solenoid requires a draw of .3 or .4
    a 2 valve circuit
  8. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,436

    You done well pilgrim, not 100% but a very good answer :clapping:
    The resistance of a multiple valve circuit is equal to the resistance of the solenoid divide by the number of solenoids in the circuit. (30 ohms/2=15 or 45 ohms/3=15)

    The transformer output is a result of the line power, primary windings and the secondary windings. I use voltage measurements for many different reasons, most of them are comparison or identification.

    Right, holding current averages between 180 and 250 mA.
    .628/2=314 while .628/3=209
    I measure resistance by clamping the common. While this is not the recommended placement, it works well for me.

    The controller displayed acceptable voltage, the resistance told you that you had either a Multi valve circuit or a bad solenoid by the amperage tells you that there are 3 and not 2 valves.
    The object is to Know and not guess, every time I help someone I too learn.

    There are many ways to find issues, faults and compromises but you actually have to posses testing equipment and use it to benefit from the information you can gather.

    Getting to my point of order of importance, I don't care what the current or voltage is when all I am doing is locating a valve, I'm interested in locating the valve. In these cases resistance is the only measurement I will perform.

    I use amperage to identify uncompromised wires when sorting, I also use voltage for identification.

    I'm done for now, nice work cape guy!!!!!!
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