I have a 4-zone sprinkler system. I had a construction crew at my house, and it appears they cut 1 of the 5 wires before pouring new concrete on top. Therefore, only 3 of the 4 sprinkler zones work.

Short of tearing out lots of concrete to find the cut wire, I cannot repair the wire. I tried letting 2 zones share one wire, but I don't have enough water pressure to support 2 zones at the same time.

The only thing I can think of is that I might be able to install the timer outside, underground in the box with the solenoid valves. I have a few questions...

Is this a feasible idea? If so, how should I do it?

  • Are there any companies that make waterproof, underground timers specifically for this purpose? If not, can I use a "regular" timer that I put in a box?

  • Where do I convert from 110V to low voltage? In the house or in the box? The four good wires are typical sprinkler wires (18 gauge?). Can this handle 110 AC electricity? Or should I use be using the "black box" to convert to low-voltage before using the sprinkler wire.

Timer | ------------------ 1 cut wire ---------------- | underground box in house | ================= 4 good wires =============== | with valves

2 Answers 2


You would not use the existing good sprinkler wires to bring the 120VAC out to the valve box. The wires are not rated and approved for that type of use. Place the converter transformer indoors to step the 120VAC down to the 24VAC. The "good" wires could then be used to route the 24VAC outdoors.

I would not use the sprinkler timer in the valve box. It would be very inconvenient to use it in that manner and the underground environment is highly likely to not be friendly to the control unit circuitry. Instead you should install an outdoor timer unit on an exterior wall above the valve box. (Use "outdoor sprinkler timer" in Google to see a selection of possible timers). The better outdoor timers have a lid that closes over the controls to protect the interior from the elements. You could then use a PVC conduit to route the necessary wires from the timer down into the valve box to keep things neat.

Do select the timer as one that works off the low voltage.

  • Thanks for your answer. The problem is that the valve box & grass I'm trying to get to is not near the house. If I were to mount it to the house and use PVC conduit (like you say), it would either involve putting a hole in the cement and tunneling, or running the conduit above ground creating a trip hazard in the middle of my driveway & sidewalks. Is there any problem with the timer-in-box approach other than the inconvenience? I'd be willing to live with inconvenience to avoid touching the concrete.
    – Keith
    Commented Jun 24, 2016 at 19:30
  • @Keith - Then poke a 4x4 or 4x6 post in the ground near the valve box to mount the outdoor controller to. That will put it above ground and make it much easier to operate.
    – Michael Karas
    Commented Jun 24, 2016 at 19:37

Keith, You can fish in a new wire under the cement. I have done this quite a few times using a 1/2" stick of PVC pipe connected to a water hose. Dig a small trench next to the cement slightly deeper if larger compacted rock was used some times it it is easier to go below the rock. Connect the PVC to a garden hose and start drilling your hole by pushing into the soil and pulling back. You will need a place for the water to drain to although sometimes after a few feet not much comes back. Just keep puling back and pushing forward. I have used this method to drill over 30' having 4 unions in the pipe (the unions make it a bit tougher).when I have the pipe to the other side dig down to it and ether use the pipe to pull the wire in or use the pipe like a conduit. I have used up to 1" pipe to do this 1" takes forever, 1/2" & 3/4" not so bad. I would pull in a extra line or two if 1 was damaged others may have had the insulation skinned and could fail at a later time. I think this would work better than trying to find a controller that is rated for an under water location (boxes in the ground during winter months regularly fill with water in most areas).

  • It's about 5o or 60 feet of concrete, under my driveway and sidewalk. Is that feasible?
    – Keith
    Commented Jun 24, 2016 at 19:31
  • 1
    I haven't gone that far but it would be better to try. I don't like conduit on top of the cement. If you have good water pressure you can go through heavy gravel. Do you know if your wiring to the solenoids can handle 120Vac?The sprinklers I have put in the low voltage wiring was only rated to 50V of I remember correctly. If the wiring is 120+ rated maybe putting a weather tight box outside would be the way to go.
    – Ed Beal
    Commented Jun 24, 2016 at 20:45

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