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I bought an older home with an existing lake-feed 2-zone irrigation system. The system uses manual valves near the 220v 1.5 hp pump, no zone controller. I want to replace the manual valves with electric valves, and add a controller.

So I need both 220v and 110v at the lake. An existing 10 gauge cable (white, black, and ground) is in place underground to the lake and protected by a 2-pole 15 amp breaker. Note: (My older breaker box has only has ground bar, no neutral bar…

Can I safely tie into one side of the line for the 110v to power the controller?

Thx!

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    You don't have "one side of the line" to tie into. The only way you get 110V from a 220V supply is by connecting between one of the Hot wires and the Neutral wire, and you don't have a Neutral wire to connect to. No you can't use the Ground wire for that. No no even just this one time. Can you not find a zone controller which runs off 220V?
    – brhans
    Aug 2, 2022 at 13:25
  • To have 120volt circuit, you need a hot(usually black) a neutral(must be white or grey) and should(must ) have ground for safety. 220/240 volt circuit need two hots(one hot sometimes uses the white wire) plus ground(which you have). You will need to add another other wire for the second hot and change the white wire to be a neutral. Your breaker box will also need to have neutral in it. You might find controllers to work with the 220, or find the manual valves not too bad.
    – crip659
    Aug 2, 2022 at 13:26
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    Can we please see the nameplate off the controller? Does the manufacturer really have no 240V options? Aug 2, 2022 at 16:50
  • A couple of comments: If the pipe going into the lake is metal, probably no need for a GFCI, if plastic, yes, that's a good suggestion. Next: getting a PSU (Power Supply Unit?) that provides the appropriate voltage to the controller and can accept up to 240v is probably the cleanest way to go. The only issue with that is the outlet must be a proper NEMA outlet for 240V. The PSU would probably have a typical 120V plug, so an adapter would be required. You clearly don't want to install a 120v NEMA outlet on a 240v circuit, if someone used it for a 120v device, things could get exciting!. Aug 2, 2022 at 17:05

2 Answers 2

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You don't have enough wires for that.

You have 240 (not 220 for many decades) as Hot, Hot, Ground.

For 240 and 120 (not 110, for many decades) you need Hot, Hot, Neutral, Ground.

Your simplest solution is a transformer; Or get an irrigation controller with 240VAC input. Ideally, just find an irrigation controller that takes 24VAC input (which tends to be what they use for valve control anyway, so they normally need one) and get a 240-24V transformer. Or get a 240-120V transformer. Or run new wiring, which tends to be expensive.

The transformer "VA" rating needs to be equal to or larger than the input Volts * Amps of the controller.

If the two-pole breaker feeding this is not a GFCI breaker, you should think long and hard about upgrading that to a GFCI. Underground to a pump at a lake you really, really want GFCI protection, even if the installation is old enough to be grandfathered rather than having been a violation from the day it was installed. After all, you did mention doing this safely.

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    There may be more irrigation controllers compatible with 240VAC input than OP thinks, as the whole of Europe (and other places besides) use ~240VAC only. It would not surprise me if to avoid having two models, you can find a model that works with both.
    – abligh
    Aug 3, 2022 at 6:12
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Three approaches that do not require running 120V to the lake, which I assume is distant from your panel and requires some underground or overhead work.

  1. (my choice) Buy a zone controller with an external PSU. There are lots of these available, and the external PSUs usually accept 100 to 250V AC input, and if not, you can buy a replacement PSU that does. Then you just install a 220V outlet for the controller.

  2. Use a transformer. You only need a tiny one. A zone controller should use about 0.1A.

  3. For just two zones, a cheap and easy alternative that not only eliminates the 120V supply but also eliminates the separate zone valves would be to use a pair of battery-powered "hose timers" that independently control each zone. You just plumb them in line with the existing manual valves. There are also two- and four- zone versions of these, but with cheap battery powered devices I like to go with simplicity and redundancy because they don't last very long.

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    There are also solar powered zone controllers (which can be had with valve included, for not terribly much more cash out the door) that don't have batteries to die. Supposedly longer life (they use ultracapacitors, so really no battery aging) but I can't vouch for that part personally, for some years yet. They do offer "larger than hose" valves, which the hose-end timers might be difficult for on a 1.5 HP pump system.
    – Ecnerwal
    Aug 2, 2022 at 14:55
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    Sunshine for solar probably corresponds nicely to the need for irrigation.
    – jay613
    Aug 2, 2022 at 15:41
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    But I have to stress, cheap battery operated hose timers don't usually last until their batteries die. Consider them annual disposables.
    – jay613
    Aug 2, 2022 at 15:43

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