I'm running the electric for a home theatre; I've installed lighted movie posters that plug-in to standard electrical outlets. The lights within the boxes are LED light strips with transformer/reducer boxes on the plugs.

I have one 2-gang outlet box on one wall; another 2-gang on the opposite wall (each with three lighted posters which means three of the four outlets per group are in-use). The circuit goes back to a Gosund Wi-Fi 3-Way switch (setup as single-pole). I've installed (literally) hundreds of the Gosund Wi-Fi switches, but never one that's controlling outlets (only lights).

When the switch is off, I'm reading 73 volts on the outlets when there is nothing plugged in. When you plug in one poster, the reading drops to 33 volts, then drops to 18 volts when you plug in the 2nd (and that's with the switch OFF)

I assumed with 73 volts on an "off" plug, there must be some ground contamination; so I took the wi-fi plug off and replaced with standard; and it's fine. No leakages.

I've read that wi-fi switches do send current even when off; but 73 volts? That seems like a lot. And, no clue why it drops as you plug in more "stuff"; unless the transformers are soaking up some stray voltages.

I've also swapped out the wi-fi switch itself - same result.

Hoping someone with more experience with wi-fi switches could help me troubleshoot :)

  • How did you make it single pole? Did you double check the wiring ?
    – Ruskes
    Jun 22 at 2:21
  • What is "ground contamination" in this context?
    – brhans
    Jun 22 at 3:21
  • 2
    I've installed (literally) hundreds of the Gosund Wi-Fi switches does not match up well with Hoping someone with more experience with wi-fi switches could help me troubleshoot :) because you're not likely to find very many others here who have installed hundreds of WiFi switches (any brand, though actually I think the brand is quite relevant). Jun 22 at 4:47
  • 3
    re: "wi-fi switches do send current even when off; but 73 volts?"; voltage is not the same as current. A shock from a winter doorknob is 10,000+ volts. Your voltmeter works by placing a tiny resistive load across the terminals, typically 1M or 10M ohms. That tiny amount of load already drops the voltage from 110/220 to 73, implying that there's very little current available. the voltage should pose no problem but you can add a nitelight to the output circuit if it does.
    – dandavis
    Jun 22 at 9:48

4 Answers 4


A few things:

  • Is this thing actually UL or ETL listed? Some of the Gosund listings mention UL or ETL, but I am somewhat doubtful. This is absolutely critical for any permanently installed devices. (Technically this is important even for plug-in devices, but if a plug-in devices starts smoking you can yank it out of the wall. With a permanently installed device the problem is a lot worse.) Why am I doubtful? Very little mention of safety certification. Lots of spelling and grammatical errors on the web site and the help pages, etc.
  • Is this a plain switch or a dimmer switch? A dimmer switch, even on "100%" may do things to the power output that are OK for lights but not OK for regular receptacles.
  • Does this switch require neutral? If it does, do you have it connected? If it doesn't require neutral, almost guaranteed to do funny stuff which will be no problem at all with incandescent, may or may not cause problems with LEDs but will definitely cause problems with receptacles.
  • 1
    Yeah, you could get sued for installing non-UL-listed crud if there was ever a problem or if the customer fails an inspection. Never attach anything to AC mains that is only available mail-order. The reason it's only sold mail-order is the FTC and CPSC would go after US companies selling that stuff, so that precludes bricks-n-mortar sales and sales from actually-in-US mail order companies. So it is sold by offshore "third party sellers" on eBay and Amazon, and they use Amazon Fulfillment to deliver. Jun 22 at 3:55
  • 3
    hey man relax, OP's outlet has "5 safe Frotection": img.staticdj.com/657ac853233963b3dc5983e60e756ff8_1920.jpg
    – dandavis
    Jun 22 at 9:53
  • 1
    LOL @dandavis!!
    – FreeMan
    Jun 22 at 12:13

Try plugging in one incandescent light into the circuit. I bet that makes it go away.

A lot of cheap dimmers are designed to power themselves via leaking voltage through the bulb, taking advantage of the near zero impedance of an incandescent bulb which is off. However, with LEDs, their ability to do that trick is "hit and miss".

It's also possible the unit has leakage for some other reason, like not following UL safety standards (look for a UL, CSA or ETL mark to indicate it complies)... But if it has some I am not overly alarmed with it. Plugging an incandescent night light will tell the tale, if the light does not light and the measured voltage goes to zero, then it's phantom/float voltage as knowitall thinks.

  • Smart switches with WiFi need so much power (>150mw) that they require a neutral. Given that, it's got to be leakage through the triac or it's snubber, right?
    – dandavis
    Jun 22 at 9:49

You asked for an explanation and so far I do not see one. This is actual leakage voltage that you are reading if you still had it with a standard switch it could be phantom but in your case it went to zero with a standard switch so it is absolutely not phantom! Electronic switches are made of semi conductor material that has zones that are doped positive or negative the most simple device is a diode 1 positive and 1 negative this only allows current flow in 1 direction with the exception of a slight leakage, now we start adding 2, 3 additional layers and by putting the correct charge on the control layer or “gate” we can turn the switch on or off, the additional layers and ac voltage allow more leakage, with a high quality true rms volt meter in some cases you can measure higher levels and with a meter that has lower impeadance a lower voltage is measured why is the voltage dropping when added loads in the off position? The leakage is still there but you provided a path back to the source, there will always be a slight voltage until you let the magic smoke out at that time the junction is blown apart and nothing is leaking through. So yes you have actual leakage the current is really tiny and just above the finger save voltage for a dry area exposed conductor open circuit and with the load within the finger safe limit (switch off leakage) this is well beyond electricians knowledge and is more technician/ engineers territory to explain the barrier zones or how semi conductors work but it is leaking through the junction (doesn’t happen with dc and there are many reasons why) but basically it is multiple layer devices controlling ac that have the issue to this extent.


You have something called Ghost voltage, with almost no current.

That usually happens when the wires are reversed.

The WiFi switch (not a switch, but a transistor logic) fires Solid State relay (On/Off) with right amount of Voltage. Unfortunately they can also be partially activated (unlike a wall switch).

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