Voltage loss on zone wire

I used a 500w power converter 120v to 220v for the same power adapter that coming with the Rachio G2 controller.
My problem is when I receive the signal in zone 2 valve it showed 15v only (it should be 24v) , the 24v ac solenoid valve not functioning. The wiring distance between the Rachio and the valve in zone2 is 70m. The zone one is 15m and working fine.
I used 14 gauge copper wire for the common and the zones.

I want to solve the voltage drop on zone 2 wire

I think everyone is quiet because you have a rather challenging problem. I can’t think of a clear solution, but there are a few things you may want to try:

  1. Figure out if your wire is Copper or Aluminium (color would be the clear indicator). Copper is a 2x better conductor, so you will incur 1/2 the losses over nearly 150 meters (70m there, 70m back) of wire that you have to your zone 2.
    Alas this will potentially be an expensive change, and it does not guarantee that the change will be sufficient for your needs, but if you are using an aluminum wire, you will definitely get a voltage increase by switching to copper.

  2. Switch to a 10 or 12 awg wire and/or run several pairs in parallel. The thicker the wire and/or more wires you have supporting this far away zone, the higher the target voltage will end up being. For best results you may wish to explore using a copper power cable or an outdoor speaker wire.

  3. (a bit experimental) You could get an AC transformer to “step-up” the voltage going to zone 2. Ideally you’d find a proper primary / secondary AC transformer with a “correct” turn ratio for what you need, but you could also try a standard AC transformer like this one (link), and connect black to common, white to Rachio’s zone 2 output, and Red or Orange to the wire running to your zone 2 valve (make sure that valve is no longer directly connected to Rachio, but connects via the transformer). The transformers output (blue and yellow) should theoretically be left disconnected.
    I warn you that this will work only on theoretical level, I’ve never tested this approach with Rachio / zone far away. This should nearly double your “down range” voltage, from 15V to somewhere under 30V.

There are more indirect methods too, such as an adjustable DC/AC supply controlled via an AC relay, but these would be more expensive so you may want to try other methods first.


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The 3rd choice is the best for me, cause I would go more distance with other zones, but when I connect the valve via AC transformer how the valve will close if the ac transformer continuously active or powered on all the time?
or how the rachio will send and cut-off an 24 ac signal through continues 24v ac transformer?

Connect AC transformer to the zone output of the Rachio, it will only be active when your target zone is active. If you have more than one zone to drive off of that AC transformer, you could connect the transformer to be permanently active and use individual relays to control the zone(s). How many far away zone are you planning on running?

I will use all 16th zones, the minimum is 15m for zone 1, the maximum is 250~300m for the final one.
Mostly all the remaining zones are more than 70m.
if there’s any circuit drawing shows how to connect the transformer to different relays I would greatly appreciate

Looks like you may need to use several voltage levels, depending how far away the active zone is. Voltage level needed for 70m zone will probably not be enough for 250m zone while voltage level for 250m zone may fry the solenoid 70m away.

To solve your problem a transformer with multiple wingdings (outputs) may be needed, something like this (link). The good news is that you will be able to get rid of 500w 220v to 110v power converter.

What is your voltage level at the nearby zone one (15m one)?
Also what is your voltage level right at Rachio (as measured between SC and SP terminals)?
Do you have the 250m zone already setup? What is the voltage there?

By the way, how is your irrigation configured?
Do you have independent water sources for all of the different zones?
Do you have a common water line which splits into different zones down the line?
Can you relocate the valves closer to the rachio?

@Ben_75 Some quick internet searching using"maximum wire distance between controller and valves" shows that the distances should be fine.

See ->



So I’m wondering if the 220/110 power converter is getting enough amps to the Rachio or if there is extra resisitivity on the wire. What is the resistivity reading on the circuits in question?

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Sorry for late,
1- zone 1 is perfect 28.9v AC using cat6 single 26 or 28 gauge wire.
2-I didn’t install the 14 gauge 250m wire but I checked by multimeter red end of 250m that connected to Rachio and black direct to common terminal the reading was 26.xxV. I don’t understand what is the problem

Without load, there will not be any voltage drop (which happens due to the resistance of the wire).

You can either:

  1. Switch the multi-meter to the “Ohms” measurement and measure across 250meter wire run. Keep in mind that the final impedance will be 2x that (500m total).

  2. Hookup a solenoid at the end of the 250m cable (keep in mind, for accurate results, you should have another 250m return wire) in order to induce the expected Amp load. If you don’t have a spare solenoid handy, just hookup zone one to 250m wire.


CAT6 is not designed for driving selenoids, which require much more amperage than communication circuits. If you see what amperage is being drawn by a selenoid valve, you can look up on wire tables to determine the voltage drop/100’ to be anticipated by each guage of wire. If the source is generating close to 30 volts, choose the gauge of wire that will not result in more than 6 volts of voltage drop for the 250m run.

Hi @Ben_75,

Now that I think about it, I think it is a good idea for you to buy a new solenoid from your local home improvement store and test it with 140m cable (70m round trip zone) as well as up to 500m cable (250m away zone)

If you are getting enough voltage with new solenoids, but not your current ones, than perhaps it is simply time to upgrade, your old solenoid may have a higher power requirements.

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