Z-Wave Control + GFCI: Will This Work?


I have an outdoor water feature by the patio. It is a large vase over a pond with a submersible pump. The submersible pump plugs into an outlet adjacent to the water feature. The outlet is supplied with power from a GFCI outlet in the garage.

I want to have the water feature turn off from 11 pm to 6 am. I prefer to not use a mechanical timer because a power outage will cause the clock to lose time.

Is it possible to install a Z-Wave control upstream of a GFCI protected outlet socket? I want to keep the GFCI protected outlet in the garage. I would expand the single gang box to dual-gang and install the Z-Wave control adjacent to the GFCI outlet. The outlet in the garage and the downstream outdoor outlet by the fountain would both be Z-Wave controlled and GFCI protected.

Some options for Z-Wave control are:

  • Enerwave ZWN-RSM1-PLUS Z-Wave Relay
  • Fortrezz Mimolite
  • GE Z-Wave In-Wall Smart Fan Control

(Aaron) #2

Yes. This will function as you want.


So, you’re going to cut power to the GFCI outlet via the Z wave outlet or the other way around? Because I think if the Z wave controls the GFCI, you’re going to trip the GFCI when you cut power to it, won’t you? You’re going to see a drop in current. I would check with a licensed electrician before performing this modification to your wiring.

(Michael) #4

Another option that doesn’t require any wiring:

(Alex) #5

Having a GFCI outlet upstream is going to be just fine, and is actually required for branches going outside or within a few feet from water. I have replaced all my breakers with GFCI/AFCI breakers and have lots of Zwave devices working happily. One thing to keep in mind is that if the branch going outside is often off (manually turned off or GFCI tripped) then you may experience issues with other zwave devices relying on the devices with no power as repeaters. I doubt this is likely given this device is likely at the end of the line being outside.

Cutting power to something downstream of a GFCI will not trip it. What trips GFCIs is when current finds an unintended path to ground. If you touch a live wire, some current will travel through your body towards ground so this device is designed to cut power before the current flowing through your body goes high enough to kill you (I believe death risk starts at >100mA).

Of the devices you listed:

I would consider the 1st one as it appears to have the safest form factor for wiring in an outdoor enclosure. I have a MIMOlite and would only use it for DC applications based on how it is designed (personal preference) due to safety concerns (proximity of DC/AC, no insulation to prevent unintended shorts, small screw terminals not really suitable for romex wires, etc).

I would not use the fan controller either… they are typically designed for small motors and meant to vary the speed. I doubt there is much benefit to do so with a pump if it even worked. At the very least you must ensure the pump motor has similar specification to typical fan motors…

Have you considered simply replacing the outdoor outlet with one of these:

Top outlet is always on, bottom one is switched.

(Benji) #6

Yeah it can cause a little funkiness in the mesh but nothing completely disruptive, you just might find a device or two acting a little slower but as you said, since it’s outside, it’s far less likely that it will be repeating for something else anyway.


Thanks, Michael. I bought a couple of those for our outdoor Christmas lights, but haven’t used them yet. I thought about using one of those for the fountain, but they aren’t rated for rain! It’s an outdoor controller, but not meant to be in bad weather (per instructions). Go figure! So I decided to not use one of those on the fountain which is really exposed (has a weather proof hood over the outlet). That’s why I want to put the Z-Wave controller in the garage.


Thanks, Alex. My first inclination was to use a Z-Wave outlet, but it doesn’t work in this application. I have a GFCI in the garage (100 feet from fountain). The power to the fountain taps off the GFCI in the garage. So the fountain is protected as a downstream outlet from the remote GFCI. If I convert the existing single gang j-box with GFCI to double gang and add a Z-Wave outlet adjacent to the GFCI, I have no way to get the controlled power out of the Z-Wave outlet to the fountain Romex. The outlets don’t provide any power take-off screws (like the GFCIs do) to feed a downstream controlled outlet.

So I concluded the best I could do is add a Z-Wave controlled relay fed by the GFCI. I agree with you about the small terminals on the Fortrezz. I wouldn’t have any LV DC in it for control, only 110 VAC, but still those terminals are not designed for 110 VAC 14 gauge wire (I just received one today and I’m going to use it for a doorbell alert - that’s another story).

I continued to look at products last night and found the Aeotec “Nanoswitch” which looks promising. I have the same concern about the small terminals, though. Their User Guide shows 110 VAC applications. See the first application example / use case " Wiring diagram of 120/230VAC power input." I think this is at the top of my list now.


Thanks, Benji. The Z-Wave controller will be in the garage and probably will not be relaying to anything else in the vicinity (except maybe my garage door controller). So I don’t think I’ll have any mesh problems. I’ll leave the outlet hot all winter and simply unplug the fountain pump for the winter. I need to drain the fountain and remove the pump for the winter anyway. So the GFCI and Z-Wave relay should remain in the mesh throughout the year.

(Alex) #10

I had understood that the GFCI was in the garage and that you had an outlet outdoors,downstream from the GFCI, that powered the pump. If this was the case then my suggestion of replacing this outdoor outlet with a zwave one would stand. By doing so you always have power outside on the top outlet and can switch the bottom outlet powering the pump on and off as needed.

One benefit of adding a relay after the GFCI and inside the house is that the device is better protected from the elements and thus last longer. A couple of issues I see though are that at least one of the relays you listed was rated for only 10A which may be enough for the pump but not enough for the typical 15 circuit. As far as I know all devices on the circuit must be able to handle the maximum current of the circuit so that you can draw the 15A at any outlet of that circuit. Also, if you add the relay upstream, you will only have the option to cut all power outside on that circuit/oitlet, not just the pump.


My question was in regards to both directions though. If you had a GFCI downstream of the Zwave, would turning power off to the GFCI outlet potentially trip it?

(Aaron) #12

It would not. You could confirm by flipping the break off and back on. It shouldn’t trip… hence you don’t have to reset them all every time the power goes out.

Also ground fault and arc interrupter are two totally different concepts. The arc interrupter you can tricked with any item with a motor such as a power drill… each time you start a motor there is an arc. So if you pull the trigger on a drill a few times really quick, the arc interrupter will flip thinking something is wrong with multiple arcs.

With ground fault it’s about the hot and neutral pulling the same about if amps… a spike or loss on one side causes the circuit to flip.

(Aaron) #13

Also putting the z-wave controller “downstream” of your gfci could leave your z-wave controller in harms way if your pump shorts and depending on the way the z-wave controller is wired… it may kick the gfci every time you kick the pump off.


Isn’t that exactly what I asked? SMH. So, if the GFCI is first, then the Z wave switch, the GFCI might trip every time the pump turns on or off?

(Aaron) #15

No, the on/off z-wave, then the GFCI. Will do exactly what your wanting it to.


So I took your advice and tested a Honeywell Z-Wave Plus outdoor switch. It is identical to the GE switch you suggested (same products by GE and Honeywell are made by Jasco). I have two new ones on hand to use for Christmas lights this season.

I configured it in the house close to the SmartThings controller, moved it outside, rebuilt the Z-Wave network and it came right up. Programmed it to go off at 10:30 pm and back on at sunrise. Worked like a charm!

I will winterize the fountain by draining the underground reservoir, the vase, putting the pump in the garage, and taking in the switch.

Thanks for the suggestion.

Question: Can I just unplug the switch, put it away for the winter, plug it in next spring and have it start working again? Or do I need to remove it from the network before unplugging it and putting it away for the winter? Same question goes for the Christmas light switches.


Ryan, I tested a Honeywell (Jasco) outdoor Z-Wave switch downstream of the GFCI. Works fine. No GFCI trips as the pump cycles on/off. I’m going to go with this simple solution. See my post to ritchierich just above.


Superman…I tested a Honeywell (Jasco) outdoor Z-Wave switch yesterday. It is located outdoors plugged into the power outlet feeding the fountain pump. GFCI is upstream in the garage. Worked like a champ. See my post to @ritchierich above.


@aruffell. Thanks for your input. I hooked up an existing Honeywell (Jasco) outdoor Z-Wave switch last night for a test. It’s the identical switch to the GE model. Setup, config, and testing were easy. Worked just fine - pump off at 10:30 pm and on at sunrise. See my post to @ritchierich above.

(Michael) #20

My recommendation would be to exclude it and add it again in spring unless you plan to keep it plugged in somewhere. Devices that depend on it as a repeater will fail. I am sure @JDRoberts will agree.