High phantom voltage with Shelly 1 Plus

    I have just recently installed a Shelly 1 Plus in a light switch but the Shelly doesn't react when I press the light switch. I can control the light through the Shelly app, but not by pressing the physical switch. The whole setup worked before installing the Shelly, so I know the switches are not defective.

    My current assumption is that I have too much phantom voltage on the "switching" wire. The switching wire runs parallel to some wires always carrying mains voltage, and therefore voltage is induced to the switching wire. You can see the whole setup in the image:2024-03-13 18_20_50-Präsentation1 - PowerPoint.png

    With a standard multimeter I measured 170V between "SW" and "N" when the light switch is off. I assume the Shelly can't differentiate between the 170V phantom voltage and the 230V real voltage.

    Has anyone experienced something similar or has an idea on how to fix this?

    Shellys behavior in your case is a bit strange. Normally the input responds to the L-SW connection, it works with a small DC Voltage and very low current. The phantom voltage should not play a major role. A resistor in front of the SW input could help, search for “Bukowski” in the forum. Unfortunately the posts are in German...

    You could try with 2 resistors in series, each at 390 kOhm, for better voltage resistance.